B e f o r e :
THE HONOURABLE MR JUSTICE PUMFREY
____________________
Between:
| |
HALLIBURTON ENERGY SERVICES, INC.
|
Claimant
|
| |
- and -
|
|
| |
(1) SMITH INTERNATIONAL (NORTH SEA) LIMITED (2) SMITH INTERNATIONAL, INC. (3) SMITH INTERNATIONAL ITALIA SpA
|
Defendants
|
____________________
Antony Watson QC and Guy Burkill QC (instructed by Bristows) for the Claimant
David Kitchin QC, Adrian Speck and James Abrahams (instructed by Bird & Bird) for the Defendants
Hearing dates: 19-21, 24-28, 31 January, 1-4 February 2005
____________________
HTML VERSION OF JUDGMENT
____________________
Crown Copyright ©
Mr Justice Pumfrey : Introduction
- This is an action for infringement of two European Patents (UK) numbers 1 117 894 ('894) and 1 112 433 ('433). Both relate to drill bits for drilling in rock. '894 is in respect of an invention entitled 'Roller-cone bits, systems, drilling methods, and design methods with optimization of tooth orientation' and was referred to at trial as the Orientation patent. '433 is in respect of an invention entitled 'Roller cone drill bit, method of designing the same and rotary drilling system' and was called the Force Balancing patent at trial.
- These proceedings started life in the County Court. The hearing before me, which lasted 13 days with substantial pre-reading, revealed that the subject matter of the patents was complex and more than justified the 15-day estimate that the trial ultimately received. The proceedings were not suitable for the County Court and should not have been started there.
- The patents are interrelated. The Orientation patent contains three claims, each of which is to 'a method of designing a roller cone bit'. The Force Balancing patent contains claims to a 'method of designing a roller cone drill bit' (claims 1 to 5), three independent claims to drill bits having prescribed qualities in use (claims 6, 7 and 8) and a claim to the use of the bit. The allegedly infringing bits are designed using a complex computer program called the 'Integrated Dynamic Engineering and Analysis System' software, abbreviated to IDEAS, which may be considered to be a sophisticated simulation or modelling system. The input to the IDEAS system is a design of bit produced using CAD software. The performance of that design of bit under defined conditions in specified formation (type of rock) is simulated using IDEAS. The design is adjusted by the designer in response to the results of the simulation and again simulated.
- The foregoing summary is enough to explain that apart from the usual questions of anticipation and obviousness this case raises a basic question relating to the inherent patentability of the alleged inventions. There is a serious attack on the sufficiency of the disclosure of both patents, to rebut which the patentee (to whom I shall refer as 'Halliburton') relies in part upon mutual cross-references and a cross reference to another document. All of this raises a difficulty of presentation of the issues in the case. Even at trial, there was no real agreement which patent should be taken first, the defendants ('Smith') putting the Orientation patent first but Halliburton starting off with the Force Balancing patent. In this judgment I shall deal with infringement and validity of each patent separately, taking the Force Balancing patent first.
The experts
- Smith called Professor Newland, Emeritus Professor of Engineering in the University of Cambridge and holder of the 1875 Chair in Engineering from 1976 to 2003. He has wide engineering experience both practical and theoretical, but has no experience of drilling. His evidence was supported by that of Professor Cooper, a Professor at the University of California at Berkeley with wide experience of the engineering of drilling but little direct experience of bit design. His interest is principally in cutter materials. Halliburton called evidence from Mr James Hall, who had wide experience of drill bit design and manufacture with, among others, Hughes Tool. He had no experience of the design of computer simulations with which Professor Newland was familiar, and was, I think, less accustomed to expressing himself mathematically, with which the patents are very concerned. The experts should have been complementary in their knowledge, but, in fact there was little on which Mr Hall could agree with the others. Prof. Cooper was subjected to strong criticism on the ground of a lack of experience either in computer modelling or in drill bit design. Since he knew much about drilling generally I found his evidence helpful.
Background
- Both patents are concerned with the design of roller cone drill bits, and in particular the type of bits used in vertical drilling for such purposes as oil and gas wells. Generally speaking, all such bits have three cones that rotate about their long axis. Each cone is provided with milled teeth integral with the cone or inserts made from tungsten carbide. The three cones are mounted on bearings and rotate about spindles fixed to three legs in such a way that the lower part of the side of the cone is generally in the plane of the hole bottom. The legs are welded together at their upper end which is provided with a threaded connection to which the drill string may be attached. I was provided with a number of bits in accordance with Smith's Notice of Models, which I examined to obtain a general impression of their construction. The transparent model is useful.
- The parties made a serious attempt to put all the uncontroversial matter together with the material that it was agreed formed the relevant common general knowledge in a single copy report agreed by the experts. The result (a document showing extensive markup) is difficult to read and some of the alterations are trivial. Nevertheless, the cross-examination of Mr Hall showed that on the issues apparently in dispute his views were not substantially different from those advanced by Professor Cooper, with the important exception of Professor Cooper's views on the obviousness of balancing downforce as a matter of common general knowledge. Mr Hall was anxious to emphasise that some of the matters to which Professor Cooper referred were within the expertise of the driller in the field rather than a bit designer, but in the result these differences are immaterial. Accordingly, I shall rely on the common general knowledge part of Professor Cooper's report augmented by that of Mr Hall for the background. I will only summarise the principal points of relevance here.
- A bit in use carries a very substantial weight, called the weight on bit, or WOB. This weight is made up of the drill collar and the rest of the drill string and is controlled by a tackle at the top of the string, which is supported by the derrick. Generally speaking there is a very easy introduction to the topic in the first chapter of the book called Rabia ('Oilwell Drilling Engineering: Principles and Practice' by Hussain Rabia), which is an undergraduate textbook located by Professor Cooper that is relied on as exemplifying the common general knowledge.
- The manner in which the bit penetrates rock depends generally upon the geometry of the cones in the bit and the shape of the teeth. Rounded carbide inserts are used in hard rock: they break the rock by crushing it as the tooth rolls into contact with the formation. The forces employed are substantial: the weight on bit may be as high as 60 tonnes and the rate of rotation 60 rpm. Softer formations require (in different degrees, depending upon the other drilling variables) a combination of both a crushing and a scraping action, for which the inserts or milled teeth will be more chisel-shaped. To ensure a degree of scrape, the cones are positioned so that their axes of rotation are not radial of the longitudinal axis of the hole, but are slightly offset so as either to lead or to lag a purely rolling motion, like this:
- The diagram shows a linear offset from the centre axis: obviously this can also be viewed as an angular offset from the radius of the bit. Whatever the precise orientation of the cones, the bit must be designed so that the rows of teeth each do their share of the work. It is helpful to think of the bit rotating and penetrating the formation: if a row of teeth follows the same path as another both will be doing less work. The following example is given by Professor Cooper, in which Ring A is cut by the heel or gage row of all three cones, ring B by cone 1, rings C and E by cone 2 and ring D by cone 3:
- This diagram shows that the cones in a given bit are always different from each other. Each will be subjected to different dynamic conditions at the bottom of the hole, and there is no a priori reason to suppose that they will tend to wear evenly. The movement of the teeth is composed of a rolling about the cone axis and a translational component resulting in gouging and scraping, and is not easy to visualize. The force on the teeth in contact with the formation is itself the force which rotates the cones as the drill rotates.
- The economics of drilling require that the bit be withdrawn from the hole as infrequently as reasonably possible. The rate of penetration needs to be as high as possible consistent with not causing premature wear of the bit, which obviously can destroy the advantage of a high rate of penetration if time is lost in early bit replacement. The process of 'tripping', which means the raising of the bit, is not trivial and is expensive—there may be thousands of feet of pipe to raise and uncouple. This means that durability of the drill is important and, with rate of penetration, is a primary concern of the user.[1]
- Both before and after the priority date, the task of the manufacturer of drill bits has been to achieve durability with a good rate of penetration. It is impossible to monitor conditions at the bottom of a hole and very difficult to emulate them at the surface and so a designer's job depended (and for those who do not use a simulation program, still depends) upon his ability to examine 'dull' (worn) bits and change the design in response to the pattern of wear he saw. Uneven patterns of wear in the teeth and in the cone bearings will indicate the unsuitability of a particular design for a particular formation, and it is important to appreciate that a bit that is wholly inappropriate for one combination of formation, WOB and RPM may be entirely suitable to different combination of conditions. Mr Hall had wide experience of bit design and he provided this description of dull bit analysis: '61. Analyzing the performance of previous bit designs and examination of these dull bits was the primary method of determining changes for a new bit design. Various conditions observed on dull bits would indicate improvements that could be made on a new design. …
62. For example, if a significant amount of breakage or chipping was consistently found in certain locations of the cutting structure of these dull bits, consideration would-be given to changing the number, shape or material used for the teeth in these locations. Adding rows of teeth to distribute the drilling forces may be considered. If this type of chipping or breakage was only found occasionally, the bit records for those bit runs. would be analyzed to determine if excessive WOB, excessive rotary speed or some other condition could have been the cause for the breakage. Consideration would also be given to the effects that changes to the tooth shape or quantity could have on the penetration rate of the bit. The experience and judgement of the bit designer would eventually be used to make changes to the design.
63. Another example would be if excessive wear was consistently noted in certain areas of the cutting structure, changes in the profile of the cone might be considered to decrease the amount of gouging and slicing that those teeth would experience. Again the effects that these changes would have on bit performance would be considered before changes would be made.
64. Unusual wear patterns observed on the bit would be considered in an attempt to determine possible causes for these conditions. Sharpening wear of the teeth on a bit can result from a condition known as "tracking". This condition is where as the cones rotate, one tooth falls into a crater on the bottom of the hole that has been caused by a previous tooth hitting at the same location. This condition causes a loss of penetration rate and results in wear to the cone shell as well as the teeth of the bit. Concentric rings worn into the cone shell can indicate that the bit is "running off-center" and is therefore not covering the bottom of the hole with cutting teeth in the desired locations as intended. This condition also results in decreased penetration rates and decreased bit life. Changes that would be considered to correct these conditions could include adding or removing. rows of teeth, changing the pitch scheme of teeth in the rows of teeth, changing the shape and length of teeth or other changes that a designers experience would indicate.'
- The manner in which the wear on a dull bit is reported is systematized. Both Professor Cooper and Mr Hall produced versions of a grading system proposed by the International Association of Drilling Contractors and are agreed that this system would be known to the skilled bit designer. Professor Cooper produced a 'Bit Record' which shows the history of a number of bits in a particular well, with the 'Dull Cond[ition]' specified for each.
- Accordingly, at the priority date drill bit design was in large part a matter for the skill, experience and intuition of the designer. Nobody has pointed to a comprehensive manual for drill bit designers, and I am sure that if one existed it would have been produced.
- Both patents are addressed to persons wishing both to design and use simulation systems for drill bit design. Although the claims are directed to methods of design, and are hence the concern of a designer, the underlying equipment, if I can put it that way, is a simulation system that the patents say is new. The Force Balancing patent uses a 'Rock Bit computer model' for the purpose of working out the dynamics of a rotating bit and describes the design of a bit in terms of a 'general nonlinear optimisation problem with bounds and nonlinear constraints' applied to design variables, objectives expressed in terms of the design variables and the bounds on the design variables and the constraints on the system. The design process described in the Orientation patent involves the generation of both a display and numeric outputs showing the scraping motion of the teeth of a cone and necessarily involves the computation of the tooth and cone kinematics from the ratio of bit speed to cone speed: it is not on the face of it concerned with the actual interaction of bit and rock. Plainly, therefore, the specifications are addressed to (1) engineers who understand drilling and drill bits (2) engineers who understand simulations and their graphical display and (3) if not included among the others, engineers who can understand the mathematics of the interaction of a drill tooth and rock and design the software necessary to model the dynamics and kinematics of the bit. I return to this subject in more detail below.
- Generally in considering these patents it is helpful to remember the distinction between cone kinematics, which describe the movement of the cone, and cone dynamics, which describe the forces on the cone that are responsible for the movement. As Professor Newland explained it, the kinematics are 'not in the ground. The kinematics is a theoretical exercise with the drill bit…another issue is the whole one of tooth to formation interaction.'
The Force Balancing patent
- The introductory parts of both the Force Balancing patent and the Orientation patent are rather similar. There are seven parts of the background section of the Force Balancing specification, concerned with rotary drilling generally (paragraphs [0002]- [0004]), drill string oscillation (paragraphs [0005] and [0006]), optimal drilling with various formation types (paragraphs [0007]-[0010]), roller cone bit design (paragraphs [0011]-[0014]), tooth design ([0015]-[0015] and bottom hole analysis (paragraphs [0018]-[0022]).
- The patent begins with a summary of the invention in paragraph [0001]:
'[0001] The present invention relates to down-hole drilling and especially to the optimisation of drill bit parameters. In particular it relates to a roller cone drill bit, a method of designing the same, and a rotary drilling system.'
- Paragraphs [0002]-[0004] set out very general background material, all of which I have covered in my discussion of the background above. The section on drill string oscillation is common general knowledge. Reduction of such oscillations is claimed as an advantage of drill bits designed according to the invention (paragraph [0034]), but it is not otherwise referred to in the specification. The likely sources of oscillation formed a component of Smith's argument of obviousness, where I shall discuss it.
- The section concerned with Optimal Drilling with Various Formation Types (paragraphs [0007]-[0010]) is largely the same as the section concerned with 'Rock Mechanics and Formations' in the Orientation patent. It is all common general knowledge. Set out in summary form are the factors affecting how a formation is drilled and the types of bit suitable for soft formation (long teeth, high gouge), hard formation (short rounded teeth, no gouge) and medium formation (between the two).
- The next background section, 'Roller Cone Bit Design' is the same as the corresponding part of the Orientation patent, and was accepted by Mr Hall to be common general knowledge at the priority date. Its significance is greater in the Orientation patent, but I should refer to paragraphs [0011] and [0014]. Paragraph [0011] is concerned with the shape of the cones. It is pointed out that they need not be perfectly conical or frustroconical but may have what is called a 'swollen', that is bulging, axial profile. Apart from the shape of the cone itself, it is pointed out that both the angle between the axis of the cone and the radius of the bit (the offset angle) and the angle between the axis of the cone and the plane of the bottom of the hole (the journal angle, plainly related to the angle of the cone) are design parameters and affect the rolling of the cone, which, because it cannot necessarily roll true, causes gouging and scraping which, as is pointed out, is complex in nature.
- Paragraph [0014] outlines the interrelationship of these design parameters and the effect of varying them. Two examples are given: cone angle and offset, which it is pointed out can be modified so as to increase or decrease the amount of bottom hole scraping. The other example is tooth length: 'Many other design parameters are limited in that an increase in one parameter may necessarily result in a decrease of another. For example, increases in tooth length may cause interference with the adjacent cones.'
- Paragraphs [0015] to [0017] are concerned with tooth design. Although the other paragraphs just set out a summary of the common general knowledge in respect of the range of shapes of teeth and their relationship to the formation intended to be drilled, I should just refer briefly to paragraph [0017] because the shape of the tooth and its interaction with the formation is important.
'Chisel shaped inserts have opposing flats and a broad elongated crest resembling the teeth of a steel tooth bit. Chisel shaped inserts are used for drilling soft to medium formations The elongated crest of the chisel insert is normally oriented in alignment with the axis of cone rotation. Thus, unlike spherical and conical inserts the chisel insert may be directionally oriented about its center axis. (This is true of any tooth which is not axially symmetric.)The axial angle of orientation is measured from the plane intersecting the center of the cone and the center of the tooth.'
- There is no doubt that oriented teeth were part of the common general knowledge of the designer. The angle of orientation affects the interaction of tooth and formation, and hence the relative movement (both rotational and translational) of the cone as the bit rotates. The gouging motion represents a translational movement between the tooth and the hole bottom. The movement of the tooth in the formation between the moment the tooth enters the formation and the moment it leaves takes a time and covers a distance determined by the rotation of the cone as it skids round the bottom of the hole. In the absence of a gouging motion, it should be remembered that the tooth movement can be visualised as a rolling movement about the point of the tooth, a movement whose translational element is small. The movement of the tooth in the coordinates of the hole bottom is shown by Professor Newland in Figure 7 in his principal report, explained further at transcript 1047 line 22.
- The final section on background, "Bottom Hole Analysis', sets the scene for the description of the invention. Paragraph [0018] does not call for much comment: it trivially points out that bit design affects rate of penetration, and that rate of penetration plays a 'significant role' in the economics of drilling a well.
- Paragraph [0019] begins to approach the heart of the invention:
'[0019] It has long been desirable to predict the development of bottom hole patterns on the basis of the controllable geometric parameters used in drill bit design, and complex mathematical models can simulate bottom hole patterns to a limited extent. To accomplish this it is necessary to understand first, the relationship between the tooth and the rock, and second, the relationship between the design of the drill bit and the movement of the tooth in relation to the rock. It is also known that these mechanisms are interdependent.'
This passage acknowledges the existence of 'complex mathematical models' that simulate bottom hole patterns. The bottom hole pattern is the cutting pattern left by the teeth in the formation at the bottom of the hole as the bit, subject to the WOB, rotates. The passage points out that in order to simulate the bottom hole pattern two things must be known: the way in which the tooth interacts with the formation and second 'the relationship between the design of the drill bit and the movement of the tooth in relation to the rock'. The specification acknowledges that it is known that these mechanisms are interdependent, and it could not be otherwise, because the forces acting on a cone are made up of the forces transmitted by the leg of the bit and the drag caused by the passage of the teeth through the rock along a path constrained by the geometry of the bit as it rotates in the hole.
- In pararaph [0020] the specification continues with a description of the work done on these two problems, that is, the way in which the tooth interacts with the formation and the relationship between bit design and the movement of the tooth in relation to the rock:
'[0020] To better understand these relationships. much work has been done to determine the amount of rock removed by a single tooth of a drill bit. As can be seen by the forgoing discussion, this is a complex problem. For many years it has been known that rock failure is complex, and results from the many stresses arising from the combined movements and actions of the tooth of a rock bit. (Sikarskie, et al, PENETRATION PROBLEMS IN ROCK MECHANICS, ASME Rock Mechanics Symposium. 1973). Subsequently. work was been done to develop quantitative relationships between bit design and tooth-formation interaction. This has been accomplished by calculating the vertical, radial and tangential movement of the teeth relative to the hole bottom to accurately represent the gouging and scraping action of the teeth on roller cone bits (Ma, A NEW WAY TO CHARACTERIZE THE GOUGING SCRAPING ACTION OF ROLLER CONE BITS Society of Petroleum Engineers No 19448, 1989)[2] More recently computer programs have been developed which predict and simulate the bottom hole patterns developed by roller cone bits by combining the complex movement of the teeth with a model of formation failure (Ma THE COMPUTER SIMULATION OF THE INTERACTION BETWEEN THE ROLLER BIT AND ROCK Society of Petroleum Engineers No 29922, 1995)[3]. Such formation failure models include a ductile model for removing the formation occupied by the tooth during its movement across the bottom of the hole and a fragile breakage model to represent the surrounding breakage.
[0021] Currently roller cone bit designs remain the result of generations of modifications made to original designs. The modifications are based on years of experience in evaluating bit run records and dull bit conditions. Since drill bits are run under harsh conditions, far from view, and to destruction it is often very difficult to determine the cause of the failure of a bit. Roller cone bits are often disassembled in manufacturers' laboratories, but most often this process is in response to a customer's complaint regarding the product, when a verification of the materials is required. Engineers will visit the lab and attempt to perform a forensic analysis of the remains of a rock bit but with few exceptions there is generally little evidence to support their conclusions as to which component failed first and why. Since rock bits are run on different drilling rigs in different formations under different operating conditions it is extremely difficult [to] draw conclusion[s] from the dull conditions of the bits. As a result, evaluating dull bit conditions, their cause and determining design solutions is a very subjective process. What is known is that when the cutting structure or bearing system of a drill bit fails prematurely it can have a serious detrimental effect of the economics of drilling.'
- The two paragraphs appear to recognise both that numerical techniques exist to permit the prediction and simulation of bit action on formation by combining the movement of the teeth with a model of how the formation fails under the action of the teeth, and that these techniques have been incorporated in the computer program referred to in the Ma Paper. It is suggested that what is lacking is a way of using these techniques to replace the methods of design from bit analysis described in paragraph [0021] and that this is described in paragraph [0022]: '[0022] Though numerical methods are now available to model the bottom hole pattern produced by a roller cone bit there is no suggestion as to how this should be used to improve the design of the bits other than to predict the presence of obvious problems such as tracking. For example the best solution available for dealing with the problems of lateral vibration is a recommendation that roller cone bits should be run at low to moderate rotary speeds when drilling medium to hard formations to control bit vibrations and prolong life, and to use downhole vibration sensors. (Dykstra, et al; EXPERIMENTAL EVALUATIONS OF DRILL STRING DYNAMICS Amoco report Number F94-P-80 1994).'
- This passage seems to me to carry on the discussion in paragraph [0020] of the Ma paper, which is concerned with the modelling of the bottom hole pattern, and it is dismissive in tone, suggesting that Ma's program can be used only to predict the presence of obvious problems such as tracking. Halliburton contend that the disclosure of the Ma paper, which is rather more comprehensive than paragraphs [0020] and [0022] suggest, is incorporated by reference. The words used are not, in my judgment, capable of incorporating this disclosure into the disclosure of the patent. Patent specifications should be complete in themselves and while they must be read like any other document these words do no more than dismiss the Ma paper (and the other citations) as ineffective components of the state of the art.
- Four so-called consistory clauses follow. These merely set out the four independent claims, paragraph [0024] corresponding to claim 1, paragraph [0025] to claim 3, paragraph [0026] to claim 6 and paragraph [0027] to claim 7. Less time was spent before me on claims 1 and 7 (the so-called volume claims) attention being concentrated on the 'force' claims 3 and 6.
- Evidently the structure of claims 1 and 3 is identical. Each adopts a particular criterion for the design of the bit. Claim 1 is concerned with what can be called swept volume: at least one of the geometric design parameters must be adjusted until a calculation of the volume of rock cut by the teeth on each cone (cutting structure) shows that the volumes cut are equal for each cone. Feature (e) shows the recursive nature of the process. An adjustment is made: the performance of the bit is simulated: a further adjustment is made so as to reduce the differences between the volumes cut by each cone and the process is continued until those volumes are equal. Claim 3 calls for an entirely similar process, in which the criterion is an equality of the 'axial force' acting on each cone. (There is a serious dispute as to the meaning of 'axial' here which I shall postpone until I have considered the preferred embodiment, together with the claims to the actual products, claims 6 and 7.)
- On the assumption that swept volume or axial force (the only two characteristics of the bit in use mentioned in the claims) are sensitive to one or more of the geometric design parameters, one can turn to the description of the preferred embodiment to see the manner in which it is proposed that this should be achieved.
Force balanced Roller-Cone bits
- At paragraph [0028] the patent introduces the embodiments to be described with a statement that in those embodiments
'the roller cone bit designs should have substantially equal mechanical downforce on each of the cones. This is not trivial: without special design consideration, the weight on bit will NOT automatically be equalised among the cones.'
- Three causes of lack of balance are identified in paragraphs [0029]-[0031]. These are respectively (a) asymmetric cutting structures (cones) (b) offset effects and (c) tracking effects. The cones are asymmetric because the teeth (apart from the gage row) are in different places on each cone and are different in number. The gouging and scraping effect of the cone offset (paragraph 10 above) is different from row to row between the cones. Finally, a cone that tracks one of the others will have the effect that at least one cone will be cutting more formation than the other two and the bit is out of balance.
- Paragraph [0032] suggests that substantially equalising the downforce per cone is very important and that this has been discovered by the patentee. Curiously, the words 'and greatly underestimated' are added to this assertion of importance, words that in a well-drafted document would tend to suggest that the patentee was here acknowledging that equal downforce on the cones had been recognised as at least one criterion even though its full importance had not been recognised. But this document is so poorly expressed that I am not willing to regard this phrase even as a straw in the wind. The paragraph promises that the application describes bit design procedures that provide optimization of downforce balancing 'as well as other parameters'.
- The principal advantage of equalising the downforce on the cones is said to lie in the reduction of vibration. Out-of-balance forces parallel to the axis of the hole will create a bending moment rotating about an axis perpendicular to the axis of the hole. This moment may be capable of coupling to the various oscillations of the drill string (paragraph [0034]), so contributing to instability and to uneven wear. The reduction in vibration lies at the root of the improvements in wear performance set out in paragraph [0035]. The improvements for the designer follow from the criterion adopted (equal axial force or equal swept volume) and the use of a simulation system.
- Paragraph [0037] contains a cross-reference to the application for the US equivalent to the Orientation patent. There is a dispute (based on the non-availability of the US application at the application date and the publication date of this patent) about the effectiveness of this cross-reference for any purpose. I shall discuss this passage below (paragraph 58).
The Addressee of the specification
- Before I consider the preferred embodiment, it is helpful to consider in rather more detail the qualities of the person through whose eyes the specification is to be read. I have already identified the relevant skills in general terms. The 'notional skilled person' who is the addressee of the specification has been described in various ways for various purposes. The skilled person is essentially a legal construct, and not a mere lowest common denominator of all the persons engaged in the art at a particular time. In some cases, of which this is an example, it is clear that the specification is addressed to sets of skills that in the real world would be possessed by more than one person, and such a specification can be said to be addressed to a team.
- There is no doubt that in the present case the team has at least two components. The first is the drill bit designer. Halliburton's witness Mr Hall was an example of a highly qualified real-world drill bit designer. It was accepted that a graduate engineer with three years' experience (or perhaps a non-graduate of 10 years' experience) was suitable. I think that it is not right to suggest that the specification is addressed to experienced autodidacts in a particular industry: after all, it should be usable by recent entrants. But although principles of bit design are on the evidence taught in universities, experience is also essential in what was at the priority date a largely empirical activity. But this specification calls for somebody who can carry out the computations called for by the claim. So the skilled person needs to be skilled in numerical methods in engineering computation and modelling. Professor Newland, who was too vastly skilled in this area to be representative, had the considerable advantage that he was a very experienced teacher of engineers at Cambridge and had a good idea of the skills of such persons, and he provided the guidance on this aspect of the skillset of the notional addressee in this regard. He tended to relate the relevant skills of the computer modeller, who is confronted with the three tasks of computing the kinematics and dynamics of the bit and displaying the results, with graduates studying for a master's degree who might be thought to be on the lower end of the spectrum of persons available to fulfil complex simulation tasks.
- As it happened, IDEAS, the program alleged to infringe, was very visual. It displayed simulated pictures of (for example) the bottom of a hole, or of a tooth showing the total interference with the formation caused by any specified row of inserts on a cone. But most of the screens were comparatively simple graphical depictions of the results of many calculations —see for example the Force History plots in Smith's Amended Product and Process Description (the PPD). No doubt the addressee will have access to computer programmers, themselves of high skill, capable of putting the results into a usable visual form, but that is not what this invention is about.
- In this connection, I should mention that although Smith's program had been heavily analysed, there was no evidence as to what, if any, use of the invention had been made by Halliburton and no evidence as to the constituent members of any team. Indeed, there was no evidence that Halliburton had any working computing programs for bit design.
The Rock Bit Computer Model
- Within this judgment I cannot give a discussion of coordinate systems and of transformations between them. This aspect of geometry at the fairly elementary level would , I think, form part of the common general knowledge attributable to the skilled person. The writer of the specification is not always careful to distinguish between a force (a quantity having both magnitude and direction), the magnitude of a force regardless of the force's direction, the components of a force (forces in predetermined directions whose sum is equal to the force under consideration) and the magnitudes of the components of the force. It is normal usage to agree upon a direction of particular interest, (the axis of a cone, say, or the axis of the drill string) and relate all relevant forces to that direction. The use of directional subscripts x, y and z strongly indicates that components are under consideration. Z is conventionally used for the principal axis of rotation of a body, and this convention seems to be observed.
- The skilled person realises that a drill bit rotating in rock under a weight on bit of thousands of kilograms is a very complex system. A force which is along the axis of rotation of the bit does not affect rotation. A force acting on the bit that is parallel to the axis of rotation of the bit, but displaced from it, will create a moment that tends to bend the bit away from its intended path and will no doubt rotate with the bit. A force at right angles to the bit axis will have the same effect. The skilled reader of the specification will have a mental picture of the forces acting on the bit. I do not mean to suggest that this mental picture will be anything other than qualitative. Mr Hall was at pains to point out that at the priority date the skilled bit designer based his designs upon the appearance of dull bits, not upon an estimate of out-of-balance forces. While the skilled person would realise that the uneven wear was the result of forces that were unequal, Mr Hall described the approach thus:[4]
'3 Q. Does it not therefore follow that the bit designer would be
4 aiming to design his bit, at least one of his objectives in
5 designing his bit, would be to ensure that the loads acting on
6 these bearings, as between the cones, were the same or as
7 close to the same as he could manage?
8 A. Again, running the risk with, and all due respect, loads
9 per se in the act of bit design really are not considered
10 implicitly. They are by moving [compacts] around, by deciding
11 how many cutting teeth to put on a cone, whatever. He would
12 know that he is effecting the way in which the cone would be
13 loaded, but loads per se had not been a part of bit design.
14 They are just not known, so they were not really considered.
15 Wear was the element that actually drove design modifications.'
- What Mr Hall is describing was the process of designing starting with a dull-bit analysis. I take it from this (none of the other expert witnesses had design experience) that the skilled person is not used to considering wear on a bit in terms of unbalanced forces, but in terms of the alterations which he can make which will, Mr Hall accepted, result in an improved balance.
- The description of the preferred embodiment starts with the description of the Rock Bit computer model. As logic might suggest, the model starts with the single tooth in paragraph [0040]. Figure 1 and the discussion in paragraph [0040] are intended to show how the force acting on a single tooth may be analysed by decomposing the tooth into individual elements of square cross section, each with three force components acting on them. The mathematics indicates what the inventor considers the forces to depend upon. There are three expressions, for the three components of the force upon a tooth element:
- The first of these equations states that the force along the z-axis of the element (Fze) is made to depend on the compressive strength s, the area normal to the z-axis Se, and ke, which is said rather vaguely to be 'a coefficient associated with the formation [rock] properties'. The inevitable inference is that an element is generally shaped like a matchstick. The second and third equations state that the x- and y- components of the force (the lateral components of the force) have a form rather like the forms of the expressions for sliding or static frictional forces, a resemblance which is reinforced by using µ as the coefficient. The force along the z-axis is proportional to penetration and thus to volume displaced.
- The suggestion is that the total force on the tooth can be ascertained by integrating these equations. This means (in essence) summing all the components of forces over all the elements into which the tooth has been decomposed so giving the x, y and z components of the total force F[5]. It is an entirely standard technique. The suggestion is that the coefficients k and µ can be ascertained by a lab test on samples of rock, and the advantage of using this technique is that the lab test need only be done once for a given formation. Different shapes of tooth can be accommodated in the mathematical process of integration by defining the shape of the elements appropriately but assuming that a matchstick element always experiences a force that may be expressed in the same way, as a product of two coefficients and the cross-sectional area of the matchstick.
- The difficulty here is that this is a general description of the technique, supposedly adequate to accommodate bits in which there is substantial offset and its associated gouging action. As paragraph [0041] explains:
'After having the single element force model the next step is to determine the interaction between inserts and the formation drilled. This step involves the determination of the tooth kinematics (local) from the bit and cone kinematics (global) as described bellow
(1) The bit kinematics is described by bit rotation speed O=RPM (revolutions per minute), and the rate of penetration, ROP. Both RPM and ROP may be considered as constant or as function with time.
(2) The cone kinematics is described by cone rotational speed. Each cone may have its own speed. The initial value is calculated from the bit geometric parameters or just estimated from experiment. In the calculation the cone speed may be changed based on the torque acting on the cone.
(3) At the initial time, t0, the hole bottom is considered as a plane and is meshed into small grids The tooth is also meshed into grids (single elements). At any time t, the position of a tooth in space is fully determined. If the tooth is in interaction with the hole bottom, the hole bottom is updated and the cutting depth for each cutting element is calculated and the forces acting on the elements are obtained.
(4) The element forces are integrated into tooth forces, the tooth forces are integrated into cone forces, the cone forces are transferred into bearing forces and the bearing forces are integrated into bit forces.
(5) After the bit is fully drilled into the rock, these forces are recorded at each time step. A period time, usually at least 10 seconds, is simulated. The average forces may be considered as static forces and are used for evaluation of the balance condition of the cutting structure.'
- It is the rotation of the bit that drives the cones whose teeth engage with the formation by rotating while being driven into it by the WOB, and remove material by crushing and gouging. The actual rotation of the cones is thus determined (1) by the speed of rotation of the bit and (2) the effects of the interaction of the teeth and the formation which will produce a torque acting on the cone. The essential quantity is called the cone-bit speed ratio. The cone-bit speed ratio plays an important role in the Orientation patent and much of the evidence relating to it was given while that patent was under consideration.
- Professor Newland was of the firm opinion that the three equations for the components of the force acting on a tooth element were each flawed. Although this is likely to be true what is being described is a simulation and will necessarily involve simplifying assumptions. The main problem with these two paragraphs of the specification, to which I shall return below when I consider insufficiency, is that it is accepted that the specification contains no information about how to (1) calculate the position of a given tooth in a formation as the bit rotates (2) how to calculate the forces on the tooth for each tooth in contact with the formation, and (3) how to integrate the forces so calculated to be acting on the tooth into bearing forces and bit forces.
- It is also to be noted that the patent gives no guidance as to how to calculate changes to the cone speed 'based on the torque acting on the cone'. This calculation is not called for by the claim. I do not think that the phrase 'cone speed may be changed…' could be permissive rather than an essential aspect of any model of a rotating drill bit. In paragraphs 215-220 of his principal report, Professor Newland explains his reasons for saying that the disclosure of the specification did not extend to this calculation, and he agreed in cross-examination that he considered that the specification contemplated that a simulation would inevitably involve an adjustment of the cone-bit speed ratio. I deal with this question when I consider the sufficiency of the disclosure.
- The specification next discusses the evaluation of a force-balanced roller cone bit. Paragraph [0042] discusses the balance condition of a bit with regard to three criteria, identified by reference to Figure 2. Each criterion expressed in equations (4), (5) and (6) is expressed as a maximum difference in a specified quantity between the cones. The selected criteria are (equation (4)) percentage resolved weight on cone (i.e. proportion of the WOB borne by each cone) (equation (5)) percentage resolved cone axial force and (equation (6)) percentage resolved cone moment in the direction perpendicular to the cone axis. The final criterion expressed in equation (7) concerns the radial component of the bit imbalance force whose effect is described in paragraph [0034] (see also paragraph 37 above).
- Paragraph [0042] then sets out at some length the statement that for perfect balance each of the selected quantities must be equal between cones, and the radial component of the bit imbalance force should be zero. That is all this passage says, and it adds nothing to the disclosure save to say that control of the selected quantities within some limitations will be sufficient.
- One of the questions in the case is what the claim means when it refers to the 'axial force acting on each cutting structure'. Paragraph [0042] supplies the greater part of the context. The cutting structure is without doubt the cone, and the candidates for the relevant force are the WOBi, the vertical force described as the proportion of the weight on bit taken by cone i, and the Fzi, which is the proportionate 'i-th cone axial force', that is, the component of the force acting on the cone acting along the cone's axis of rotation. The latter is shown clearly in Figure 2. It should be noted that Fr is likely to be heavily influenced by an imbalance in the Fzi, the greater the imbalance the greater the net out of balance force on the bit.
- Paragraph [0043] describes how the force balancing criteria described in paragraph [0042] are related to energy balancing criteria. Energy balancing is much easier to understand since the specification adopts as its energy balance criterion the single requirement that the volume of formation removed by each cone per revolution should be the same (see equation (11) in paragraph [0048]). This is the method of claim 1, which is not alleged to be infringed.
'[0043] There is a distinction between force balancing techniques and energy balancing. A force balanced bit uses multiple objective optimization technology, which considers weight on bit, axial force and cone moment as separate optimization objectives. Energy balancing uses only single objective optimization as defined in equation (11) below.'
- The specification turns to the design of a bit in paragraph [0044] and the following paragraphs. This description is entirely in terms of volume or energy balancing, it being stated in paragraph [0046] that the inventor has found that an energy balanced bit 'will lead to force balanced in most cases'. A series of steps are described:
(a) Selection of design variables. In the simplified example given by reference to Figure 3, these are tooth-related, the cone profile, offset and journal angle being assumed to be invariant. The design variables are the radial position of the tooth, the length of the crest and the tooth angles.
(b) Definition of objectives, and expression of objectives as function of design variables. In the example given, the objective selected is to let each cone remove the same amount of rock in one revolution of the bit. It appears to be assumed that the bit has a specified cutting depth per revolution (it is called ., and is never referred to again in the specification). It is then stated that
'It is not difficult to calculate the volume removed by each row, and the volume matrix may have the form
.png)
This expression is vacuous: it states that there exists a matrix V which describes the amount of rock removed per row of teeth (the index j) and per cone (the index i). So far as the patent is concerned, all the Vij are to be calculated as functions of the design variables. There is no disclosure in this document of a method (an algorithm, an analytic expression or whatever) for doing this. The matrix V is not the end of the matter, because it is recognised that the matrix calculated in a 2-D manner, which I assume means on the assumption of a cone rolling about a radius with no offset, must be further modified by a scale matrix, the elements of which reflect the number of teeth and the tracking condition. I quote paragraph [0047]:
'In reality the removed volume by each row depends not only on the above design variables, but also on the number of teeth on that row and the tracking condition. Therefore the volume matrix calculated in a 2D manner must be scaled. The scale matrix, KV may be obtained as follows.
.png)
where V3d0 is the volume matrix of the initial designed bit (before optimization). V2d0 is obtained from the rock bit computer program by simulate the bit drilling procedure at least 10 seconds [sic]. V2d0 is the volume matrix associated with the initial designed matrix and obtained using the 2D manner based on the bottom pattern shown in Figure 4. The volume matrix has the final form
.png)
In fact, equations (9) and (10) are the same. Equation (10) repeats the information that the matrix is a function of the four variables identified in paragraph [0045], that is the selected design variables. Paragraph [0046] told us that the elements Vij of the matrix V are functions of the design variables. The actual objective is identified finally in paragraph [0048], which is to minimise the root mean square deviation in volume removal between the cones.
(c) Define the bounds of the design variables and the constraints. This stage is described in paragraphs [0049]-[0051]. Examples are given (minimum tooth crest length, for example) and it is emphasised that it is particularly important to avoid interference between teeth on different cones during rotation, and to specify the width of the uncut rings on the hole bottom. Further expressions are given which merely repeat what is said in words (equations (12) and (13)). These are purely geometrical constraints.
(d) Solution of the problem. Paragraph [0052] describes how to carry out the optimization of the design.
'[0052] After having the objective function, the bounds and the constraints. the problem is simplified to a general nonlinear optimization problem with bounds and nonlinear constraints which can be solved by different methods. Figure 6 shows the flowchart of the optimization procedure. The procedure begins by reading the bit geometry and other operational parameters. The forces on the teeth, cones: bearings, and bit are then calculated. Once the forces are known, they are compared, and if they are balanced, then the design is optimized. If the forces are not balanced, then the optimization must occur. Objectives, constraints. design variables and their bounds (maximum and minimum allowed values) are defined, and the variables are altered to conform to the new objectives. Once the new objectives are met. the new geometric parameters are used to re-design the bit, and the forces are again calculated and checked for balance. This process is repeated until the desired force balance is achieved.'
It is worth observing that the whole of the description of the preferred embodiment, this passage apart, is concerned with volume balancing, as paragraph [0054] makes clear. That paragraph explicitly states that once volumes are equalized, force balancing is also achieved. This is inconsistent with paragraph [0043] and slightly inconsistent with paragraph [0046], where it said to happen 'in most cases'. I do not think this particularly matters.
The relevance of the Orientation patent to the Force-balancing patent
- Generally speaking, the specification of the Force Balancing patent is remarkable for the small amount of information it gives on how actually to perform the volume calculations and the force calculations which are called for by the claims. The expressions actually given are entirely trite and add nothing to the verbal disclosure, merely repeating it in a somewhat more compact form. This has led to a wide-ranging allegation of insufficiency, which has in turn led to a suggestion by Halliburton that the disclosure of the specification could for all purposes be taken to include the disclosure of the Orientation patent and also of the Ma paper, which it was not contended was common general knowledge but was said to be incorporated by the combined effect of paragraphs [0020] and [0022]. I shall deal with the disclosure of the Ma paper below. I am satisfied that there is no question here of incorporation of the disclosure of the Orientation patent by reference for two reasons. First, for the reason I have given in paragraph 38 above, the words of paragraph [0037] do not direct the skilled man to
'US Patent Application 09/387,304 filed 31 August 1999' if he wants any information about how to implement a bit design system according to this invention. I quote the passage: 'U.S. Patent Application 09/387.304, filed 31 August 1999 (issued as US patent 6.095,262), entitled "Roller-Cone Bits, Systems, Drilling Methods, and Design Methods with Optimization of Tooth Orientation" (Atty. Docket No. SC-98- 26), and claiming priority from U.S. Provisional Application 60/098.442 filed 31 August 1998, describes roller cone drill bit design methods and optimizations which can be used separately from or in synergistic combination with the methods disclosed in the present application.'
Let me take an example. If the designer is interested in force-balanced bits with conical inserts, whose cutting effect does not depend upon orientation, why, one might ask, should he look at this specification at all? There is no direction to consult the specification with a view to obtaining further information on the modelling techniques called for by the claim. I do not think it is legitimate as a matter of interpretation to take a passage such as that above and build out of it a suggestion that if the skilled person is at a loss as to how to proceed, the solution to his problem is, or may be, available in the cited publication. For this reason, the disclosure of the Orientation patent is not part of the disclosure of this patent, and I can interpret the claims without regard to it.
- The second reason is that I am of the view that the application for the Orientation patent cannot, in the somewhat unusual circumstances of this case, be a legitimate cross-reference in any event. This conclusion is an alternative reason for my decision to take no account of the Orientation patent and may be of some practical importance to those who file patent applications at the EPO. I set out the steps of the reasoning in Annex A below in order to avoid disrupting this discussion.
- The reference to the Ma paper is summarised in paragraph 29 above. As a matter of construction, this is the thinnest possible basis for a suggestion that the disclosure of the paper is to be incorporated in the patent. It seems to me that the specification does not point the addressee in the direction of the Ma paper for the purpose of supplementing its disclosure for any purpose. It is a description of the background prior art. I think that the Ma paper is really disclosed as a record of the existence of a computer program which does not do what the claim requires, in other words a failed proposal. If the patentee had wished to use the disclosure of Ma, the cross-reference should have been express.
- In general, cross-referencing for the purpose of supplementing the disclosure is highly undesirable, and is not permitted by the EPO, which deals with the matter as follows in its Guidelines for examination Chapter C-II:
'4.18 Reference documents
References in European patent applications to other documents may relate either to the background art or to part of the disclosure of the invention.
Where the reference document relates to the background art, it may be in the application as originally filed or introduced at a later date (see II, 4.3 and 4.4).
Where the reference document relates directly to the disclosure of the invention (e.g. details of one of the components of a claimed apparatus), then the examiner should first consider whether knowing what is in the reference document is in fact essential for carrying out the invention as meant by Art. 83:
If not essential, the usual expression "which is hereby incorporated by reference", or any expression of the same kind, should be deleted from the description.
If matter in the document referred to is essential to satisfy the requirements of Art. 83, the examiner should require the deletion of the above-mentioned expression and that, instead, the matter is expressly incorporated into the description, because the patent specification should, regarding the essential features of the invention, be self-contained, i.e. capable of being understood without reference to any other document. One should also bear in mind that reference documents are not part of the text to be translated pursuant to Art. 65.'
- I am not concerned with how an application is to be examined, but this principle is a sound one. If the disclosure is essential to the patent that fact should be made abundantly clear. As a matter of the ordinary principles of document construction it is not permissible to exclude the possibility of a cross-reference for essential material: but the court must, I think, be on its guard to ensure that the cross-reference is a proper one. This is not such a cross-reference.
- Accordingly I must interpret the claims in their context in the specification, ignoring the cross-reference to Ma and to the optional features disclosed in the application for the Orientation patent.
The claims of the Force Balancing patent
- It is convenient to deal with the method claims and the product claims separately. The two independent method claims, 1 and 3, are set out above but I repeat them for convenience:
Claim 1:
A method of designing a roller cone drill bit comprising a plurality of arms rotatable cutting structures mounted on respective ones of said arms and a plurality of teeth on each of said cutting structures, the method comprising the steps of
(a) calculating the volume of formation cut by each tooth on each cutting structure (16) of the roller cone drill bit (10);
(b) calculating the volume of formation cut by each cutting structure per revolution of the drill bit;
(c) comparing the volume of formation cut by each of said cutting structures with the volume of formation cut by all others of said cutting structures of the bit;
(d) adjusting at least one geometric parameter on the design of at least one of the culling structures; and
(e) repeating steps (a) through (d) until substantially the same volume of formation is cut by each of said cutting structures of said bit (10) when the drill bit is drilling into a formation.
Claim 3:
A method of designing a roller cone drill bit comprising a plurality of arms, rotatable cutting structures mounted on respective ones of said arms and a plurality of teeth on each of said cutting structures, the method comprising the steps of:
(a) calculating the axial force acting on each tooth (18) on each cutting structure (16) of the roller cone drill bit;
(b) calculating the axial force acting on each cutting structure per revolution of the drill bit;
(c) comparing the axial force acting on each of said cutting structures with the axial force on the other ones of said cutting structures of the bit;
(d) adjusting at least one geometric parameter on the design of at least one of said cutting structures; and
(e) repeating steps (a) through (d) until substantially the same axial force will act on each cutting structure when the drill bit (10) is drilling into a formation.
- The claims raise two common points on construction, the meaning of the words 'repeating…until…' and of the concluding words 'when the drill bit (10) is drilling into a formation'. The second problem arises on claim 3 only, and that is to identify the axis referred to in the phrase 'axial force'.
Construction—when a drill bit is drilling into a formation
- This phrase appears also in the product claims 6 and 7. In their context in claims 1 and 3, Smith submit that the words plainly refer to the process of simulation. Both of the method claims use the word 'cut' to refer to the material calculated to have been cut and it is submitted that to suggest that the reference is to a bit cutting in the real world cannot be supported. The reference is plainly, it is said, to the simulation of the cutting action of the bit in the simulated formation. This is not the end of the this matter, which needs further consideration when the designers' evidence of the way in which they use the IDEAS software is considered, in paragraph 114 below. I accept the main thrust of Smith's submission, and I do not understand Halliburton to dissent from it.
- When one turns to the product claims, on the other hand, Smith contend that the words can only refer to the real world, and the formation referred to is real rock. Since the claims are not limited to bits made by simulation according to the method claims, it is said that there is no other way of interpreting this requirement. I consider this question below.
Construction: 'axial force'
- These words appear in features (a), (b), (c) and (e) of claim 3. Halliburton say that the axis referred to is the axis of the drill string and the bit, i.e. the axis of the hole drilled: Smith say it is the axis of the cone. I have found it very difficult to decide between these possible constructions, the more so because the specification is far from clear or coherent. The principles to be applied are set out in Lord Hoffmann's speech in Kirin- Amgen v TKT [2004] UKHL 46, paragraphs 30-35. Given the approval that is given in that speech to the observations of Jacob LJ in Rockwater Ltd v Technip France SA [2004] EWCA Civ 381 I shall set out that useful list of applicable principles. I take the responsibility for modifying principles (e) and (f) slightly to take account of the single criticism that Lord Hoffmann makes of this list.
'(a) The first, overarching principle, is that contained in Art 69 itself. Sometimes I wonder whether people spend more time on the gloss to Art 69, the Protocol, than to the Article itself, even though it is the Article which is the main governing provision.
(b) Art 69 says that the extent of protection is determined by the terms of the claims. It goes on to say that the description and drawings shall be used to interpret the claims. In short the claims are to be construed in context.
(c) It follows that the claims are to be construed purposively – the inventor's purpose being ascertained from the description and drawings.
(d) It further follows that the claims must not be construed as if they stood alone – the drawings and description only being used to resolve any ambiguity. The Protocol expressly eschews such a method of construction but to my mind that would be so without the Protocol. Purpose is vital to the construction of claims.
(e) When ascertaining the inventor's purpose, it must be remembered that he may have several purposes depending on the level of generality of his invention. Typically, for instance, an inventor may have one, generally more than one, specific embodiment as well as a generalised concept. But there is no presumption that the patentee necessarily intended the widest possible meaning consistent with his purpose be given to the words that he used: purpose and meaning are different.
(f) Thus purpose is not the be-all and end-all. One is still at the end of the day concerned with the meaning of the language used. Hence the other extreme of the Protocol – a mere guideline – is also ruled out by Art 69 itself. It is the terms of the claims which delineate the patentee's territory.
(g) It follows that if the patentee has included what is obviously a deliberate limitation in his claims, it must have a meaning. One cannot disregard obviously intentional elements. Hoffmann LJ put it this way in STEP v Empson [1993] RPC at 522:
"The well known principle that patent claims are given a purposive construction does not mean that an integer can be treated as struck out if it does not appear to make any difference to the inventive concept. It may have some other purpose buried in the prior art and even if this is not discernible, the patentee may have had some reason of his own for introducing it."
(h) It also follows that where a patentee has used a word or phrase which, acontextually, might have a particular meaning (narrow or wide) it does not necessarily have that meaning in context. A good example of this is the Catnic case itself – "vertical" in context did not mean "geometrically vertical", it meant "vertical enough to do the job" (of supporting the upper horizontal plate). The so-called "Protocol questions" (those formulated by Hoffmann J in Improver v Remington [1990] FSR 181 at p.189) are of particular value when considering the difference of meaning between a word or phrase out of context and that word or phrase in context. At that point the first two Protocol questions come into play. But once one focuses on the word in context, the Protocol question approach does not resolve the ultimate question – what does the word or phrase actually mean, when construed purposively? That can only be done on the language used, read in context.
(i) It further follows that there is no general "doctrine of equivalents." Any student of patent law knows that various legal systems allow for such a concept, but that none of them can agree what it is or should be. Here is not the place to set forth the myriad versions of such a doctrine. For my part I do not think that Art. 69 itself allows for such a concept – it says the extent of protection shall be determined by the terms of the claims. And so far as I can understand, the French and German versions mean the same thing. Nor can I see how the Protocol can create any such doctrine.
(j) On the other hand purposive construction can lead to the conclusion that a technically trivial or minor difference between an element of a claim and the corresponding element of the alleged infringement nonetheless falls within the meaning of the element when read purposively. This is not because there is a doctrine of equivalents: it is because that is the fair way to read the claim in context.
(k) Finally purposive construction leads one to eschew what Lord Diplock in Catnic called (at p.243):
"the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge."
Pedantry and patents are incompatible. In Catnic the rejected "meticulous verbal analysis" was the argument that because the word "horizontal" was qualified by "substantially" whereas "vertical" was not, the latter must mean "geometrically vertical."'
- I would diffidently add three observations of my own. The first is merely the trite principle that the addressee of the specification is the person skilled in the art, who approaches the document with the common general knowledge. Second, there may be obscurities and difficulties in a claim that cannot be resolved by an appeal to context. It is very rare that some sensible meaning cannot be attributed to the words used in a patent claim, but where a claim permits alternative interpretations it is possible to be left with no alternative but to take the most straightforward. Finally, and most importantly, over-meticulousness is not to be equated to carefulness. Care in working out what the patentee was aiming at when he chose the words he used is absolutely necessary.
- Turning to claim 3, the context in which the claim is to be interpreted in this case may be summarised as follows.
- Existing roller cone bits, designed incrementally from pre-existing bits, are generally not balanced (paragraph [0029]). The bits made using the invention should have substantially equal mechanical downforce on each of the cones, that is, the WOB will be equalized among the cones (paragraph [0028]) when in use. Substantially equalized downforce is a greatly underestimated factor in roller cone performance, in particular reducing gyration, and the patent describes bit design procedures which provide optimization of downforce balancing (paragraph [0032]). The improved performance of balanced-downforce cones may be partly due to the reduction in oscillation caused by reduction in bending moments (paragraph [0034]).
- A bit should be made using the described Rock Bit Computer Model. The balance condition of a bit designed in this way may be evaluated using three criteria identified by reference to Figure 2: equalisation of the downforce on each bit (equation (4)) so that each cone carries about one-third of the total WOB; equalization of the cone axial forces (equation (5)); and equalization of the per-cone moments perpendicular to the cone axes (equation (6)). Generally speaking each of these variables has to be controlled within limits and if they are the bit will be balanced (concluding words of paragraph [0042]). All three will be equalized if volume of rock cut per bit revolution is equalized between the cones (paragraph [0046]).
- This summary shows that the problem of identifying the axis referred to by the word 'axial' is caused by the patentee's use in the claim of exactly the same words to specify the force to be balanced as are used in paragraph [0042] of the specification to describe one only out of three (or four) quantities each of which needs to be equalized if (in the specification's terms) the balance condition is to be achieved. In paragraph [0042] other forces are described, one of which is the per-cone downforce, or WOB, which is of course the force that Halliburton says is being referred to by the claim. It therefore looks as though the draftsman has made a clear choice in the claim between the various forces that are candidates for balancing, albeit a choice that may be thought to be odd having regard to the importance attributed by the specification to the equalization of downforce in paragraphs [0028]-[0035], and has selected the coneaxial force. The impression that a deliberate choice has been made is only reinforced when it is remembered that each of the three variables, weight on bit, axial force and cone moment, are expressly described as 'separate optimization objectives' in paragraph [0043]. Claim 3 is thus a claim to equalizing one of the 'separate optimization objectives'. So construed in context, 'axial' refers to the cone axis.
- A different approach to the problem is this. The volume balance that is the subject of claim 1 will, so far as the specification is concerned, achieve the overall balance that is desired and will when achieved include the balance in downforce. What then is the reason for claim 3? Why single out one criterion (cone axial force) nowhere discussed in detail distinctly from the other four criteria? The specification itself makes it clear in a lengthy passage that downforce balance is highly desirable, and no particular significance is attached to the other three quantities. Since the WOB is in fact an axial force, albeit along another axis not referred to in the specification or labelled in Figure 2, the context that matters for claim 3 is provided by paragraphs [0028] – [0035]. The use of terms for the WOB in the claim that are not used elsewhere in the specification and have been used in respect of another force described with reference to Figure 2 is certainly unfortunate but would not cause the skilled reader any difficulty.
- Furthermore, the 'cone axis' construction does not solve a similar problem that arises with the first feature of the claim ('calculating the axial force acting on each tooth on each cutting structure…') which plainly refers to the axis of the tooth at this point in the claim. Figure 2 does show such forces labelled WOBi. Although they are labelled in a way that suggests that they represent the tooth's total fraction of the WOB, it is quite possible to view them as the axial components of WOB relative to tooth axis. These then are the components to be calculated using the Rock Bit Model, and it follows that 'axial' is referring to the drill bit axis.
- Obviously there is something to be said for both interpretations. I approach the problem in this way.
(a) Given that the words 'cutting structure' undoubtedly mean 'cone', the literal meaning of the words 'calculating the axial force acting on each tooth on each cutting structure' at first sight indicates the axis of the tooth, principally because when the tooth is not in formation there is no force on it. Generally speaking, a force acting on the tooth will have a component along the tooth's major axis: this is what is shown as the WOBi in figure 2.
(b) The skilled reader would realise that the forces acting on the tooth varied very substantially as the cone rotated. The specification does not say anything about the loads on the journal bearings (that is, perpendicular to the cone axis) as one of the forces to be equalized. The journals carry a substantial proportion of the WOB, as a quick look at Figure 2 makes clear. To this extent, equalisation of WOB per cone will tend to make the journal loadings more equal.
(c) The words 'axial force acting on each cutting structure per revolution of the drill bit' may be thought to suggest a different axis but the phrase 'force per revolution' read literally is more or less meaningless because the force will not increase with the number of revolutions. If one remembers that the force on individual teeth will vary greatly as they enter, interact with, and leave the uncut formation on the hole bottom as the cone rotates, it seems sensible to suppose that what the claim is probably looking at is the average axial force over a rotation of the bit, i.e. over somewhat more than one rotation of a cone.
(d) Feature (c) of the claim seems to me to throw no light on the question which axis is being talked about. To equalise forces acting along the axis of the cones makes sense, since it will tend to equalise wear on the cone thrust bearings. It is also one of the forces expressly referred to in paragraph [0042] and [0043]. To equalise WOB per cone also makes sense. Feature (c) is accordingly indifferent as to the nature of the axial force under discussion, and the same goes for (d) and (e).
(e) Claim 6 does provide some oblique support for the construction for which Halliburton contend. It calls for a bit in which in use 'the axial force on each of said cutting structure[s] is between [31%] and [35%] of the total of the axial force on the bit…'. It is only possible to construe claim 6 so as to be consistent with the meaning of claim 3 for which Smith contends if the word 'force' relates to the magnitudes of the axial components of the forces on the cones, ignoring their direction, since they are more or less at right angles to the bit axis. There is every reason to make the cone-axis components of the cone forces equal in magnitude (this is what equation (5) describes) because that will ensure that the forces acting perpendicularly to the bit axis sum approximately to zero. Nobody suggested a plausible reason for relating them to WOB at all. This claim plainly relates to the bit-axis component of the force on each cone.
- I have no doubt that the draftsman is here guilty of avoidable obscurity and ambiguity, and I think an unfair burden is placed on the reader. But I have concluded that the construction for which Halliburton contend is the right one. I reach this conclusion with some diffidence, since the contrary considerations are strong ones.
Construction: repeat…until
- This point arises principally as a problem with infringement of claim 3. The claim (and I do not understand there to be any dispute about this) calls for a repetition of the calculation of the axial force on each cone and the adjustment of 'at least one geometric parameter of the design of each [cone]' until substantially the same axial force will act on each cutting structure when the bit is drilling into simulated rock. Indeed, the case was opened on the basis that the inventive concept of this patent lies in the appreciation that the axial forces on each cone should be balanced, and that this should be done by calculating the forces on each tooth and thus on each cone, and adjusting the design and recalculating those forces until balance is achieved. In other words, the criterion according to which the designer must finally decide whether the adjustment was appropriate or inappropriate is whether it leads towards or away from equality of per-cone axial forces.
- However, I consider that this is far from abundantly clear, either from the words of the claim, or from paragraph [0052] or from Figure 6, the flow chart. The claim does not expressly suggest that the adjustment of the geometric parameter need be in dependence upon the comparison of step (c): all it says is that adjustment must take place and the process is iterated. If, therefore, a designer does not satisfy himself that his cycle of simulations is complete by reference to per-cone axial force, but adjusts his geometric parameter by reference to other criteria, albeit that the result of the application of those criteria may well be that per-cone axial force is equalised, at least to the limits of claim 6, does he infringe claim 3? To take an example, suppose it were affirmatively demonstrated that the designer did not look at the relevant output of the software, but by selecting according to other criteria nonetheless arrived at a bit which the software considered to be force balanced. I think that in such a case there is no infringement of the method claim.
- More importantly, however, it seems to me that where the criteria include axial force balance and the result of juggling the various design variables with an eye on force balance results in a force balanced bit there is infringement, even if force balance is not the sole or overriding criterion.
Construction: the product claims
- Claims 6 and 7 are as follows;
'6. A roller cone drill bit comprising:
- three arms;
- one rotatable cutting structure mounted on each one of said arms; and
- a plurality of teeth on each of said cutting structures;
wherein the number and locations of said teeth are not identical between ones of said rotatable cutting structures;
characterised in that the axial force on each of said cutting structure is between thirty-one percent and thirty-five percent of the total of the axial force on the bit when the drill bit is drilling into a formation.
7. A roller cone drill bit comprising:
- three arms;
- one rotatable cutting structure mounted on each one of said arms; and
- a plurality of teeth on each of said cutting structures, wherein the number and locations of said teeth are not identical between ones of said rotatable cutting structures;
characterised in that the volume of formation drilled by each of said cutting structures is between thirty-one percent and thirty-five percent of the total volume drilled by the drill bit when the drill bit is drilling into a formation.'
- The issue on construction. The first issue is the meaning of the phrase 'when the bit is drilling into a formation'. There is a secondary issue, important for infringment, as to the precision of the numerical limits.
- The skilled man knows after reading the specification that a given bit may be balanced in one formation but not in another. The words in question can describe a bit (balanced in such-and-such a formation with such-and-such a WOB at such-and-such RPM) but what if the designer did not have those conditions in mind when the bit was designed?
- It seems to me that the skilled man knows that there is no way of actually measuring the load on a cone in use. This means that to place Smith's interpretation on claims 6 and 7 is likely to result in a finding of insufficiency, unless it can be said that the specification provides a description of such a measurement. Smith submit that it does so: run the bit design (however made) through the simulation program disclosed, and determine whether that program says that the bit is force balanced or not.
- Halliburton do not accept any of this. They contend that the claim, purposively construed, is to a bit 'designed so as to be balanced in the design formation and parameters'. They say the claim is a claim to a bit however designed provided that it was designed to be balanced. The difficulty with this construction is that it makes the claim a 'product by process' claim but, as written, there is plainly no reference to the process in the claim. Moreover, where does this leave the bit which was primarily designed with an eye to other parameters, such as rate of penetration, but comes out balanced?
- In my judgment, the skilled reader will not construe the product claims so as to imply a method of design of the bit. I think that the claim is accordingly vulnerable on two grounds: for anticipation, because it is not limited by reference to the method by which the bit it covers was designed; and for insufficiency, because the claim covers balanced bits arrived at by methods of which the patent is completely silent.
- I have already expressed the view that read in the light of the specification as a whole these words as they appear in the method claims obviously relate to the conditions of a simulation. There is no way of measuring the force on each cone, or the material removed by each cone, several thousand feet down in rock. The product claim is however a claim to an object (a drill bit) which is not expressly required to be manufactured using a simulation technique. The phrase cannot be viewed as introducing a product by process feature, and Halliburton's contention to this effect seems to me to require a wholesale re-writing of the claims going beyond anything which might be thought to be legitimate under the guise of construction. So I conclude that in the product claims these words relate to real rock. In the end it probably does not particularly matter, because a simulation provides evidence, which may be the only evidence, of what the performance of the bit is in real rock. But all the evidence must be considered, and if the simulation is inconsistent with other evidence, then it may appear too inaccurate to rely upon.
- The second question raises a very difficult problem. All drill bits are designed and manufactured using CAD/CAM techniques. The CAD files for the bit are processed and input into the simulation, which announces that the per-cone axial load is within the numerical limits specified. But it has to be accepted that different simulations may in principle achieve different results. It was strongly argued by Halliburton that the task of the patent was only to disclose enough information to enable a simulation to be constructed, not the last word in simulations nor even a particularly accurate one. To take an important example, it was not necessary to adjust the bit/cone speed ratio at all. So a given bit, simulated in a defined formation, might or might not appear balanced according to the criteria of the claim depending upon the details of the simulation.
- I can see no reason not to give the claim a wide meaning in this respect. It must be the case that the designer of a simulation is not merely pursuing a simulation that works, but one that objectively produces at least as good a result as the prior art did with its dull bit analysis. After all, the designer of a simulation that actually produces a worse product than the prior art will have failed commercially. It follows that bit designers will be aiming for results that are better than those that dull bit analysis provides and thus that the adoption of criteria such as 'the axial force on each cone is between 31% and 35% of WOB' will have an objective meaning to those designers. Their simulation is bound to be an approximation but until two practically useful simulations can be shown to produce meaningfully different results on these criteria the problem is more apparent than real.
- In this respect, and perhaps in this respect alone, Smith were not assisted by the fact that Halliburton do not appear on the evidence to have implemented the invention of the Force Balancing patent. No evidence of fact was led by the patentees, and no other evidence given, suggesting that Halliburton had a method of simulating drill bits that fell within the claims, or, indeed, owed anything to the teaching of the patents. Halliburton could not simulate a Smith design, and so the possibility of different answers on claims 6 and 7 remained, as I have indicated, theoretical.
- For the same reason, I see no reason to construe 31% and 35% as meaning anything other than the specified number to two significant figures, so including 30.5% to
- 4%, or 30.50% to 35.49%, or 30.500% to 35.499%.[6] These are implied statements about the precision of the measurement, no more. They are not statements about its accuracy.
- Finally, I must mention the question of infringement in cases in which although the software indicates that force balance satisfying claim 6 has been achieved, the designer has not used the method of claim 3, having ignored the force balance in making his design choice. If the claim were to cover such a case, it seems to me that it would be too wide and in consequence the specification would be insufficient in the way described in detail by Lord Hoffman in Biogen v Medeva [1997] RPC 1. This would be an example of the case of a claim which covered embodiments which owed nothing to what was taught by the patent in suit. This is nonetheless a difficult question, and since I am satisfied that the claim is invalid for insufficiency on what Neuberger J called the 'classical' basis in Kirin Amgen v TKT, I do not propose to say more than to observe that this particular difficulty of interpretation is a clear pointer to invalidity on the Biogen basis as well.
Infringement of the Force Balancing patent—general
- If I am wrong on the meaning of 'axial' in the claim, there is no infringement, either of claim 3 or claim 6. Smith do not design or manufacture bits within the jurisdiction, so infringement of claim 3 is alleged by virtue of subsection 60(1)(c) of the Patents Act 1977. The invention is a process, and so the product sold in the United Kingdom must be obtained directly by means of the claimed process. 'Obtained directly' has been considered in two cases cited to me, particularly Pioneer Electronics Capital Inc v Warner Music Manufacturing Europe GmbH [1997] RPC 757, and a decision 'Halbleiter-bauelemente' in the Landgericht Dusseldorf 6 May 1997. The Court of Appeal have held that 'obtained directly' means 'without intermediary' or immediately. This seems to exclude the possibility of further processing: but the Halbleiterbauelemente case suggests that further use or processing may take place provided that its effect is not to obscure the qualities of the product directly obtained.
- The result of the performance of the claimed method is, if I am right on the question of construction, a CAD file containing a design of bit balanced under design conditions. The CAD file is input to a numerically controlled milling machine to produce (separately) the cones, either milled in one piece with the teeth or with recesses to receive the inserts, which are themselves milled to the design recorded in the CAD file. The cones are then assembled with the associated bearings, seals and other ironmongery into a bit body. Is the result 'directly obtained' by means of the process?
- Smith's approach to this question is understandably to point to the design as the endpoint of the claimed process, and to decompose the subsequent manufacturing process into as many steps as reasonably possible. Whatever is using the CAD files resulting from a session with the simulation software is not obtained directly by use of the process but (I paraphrase) by employing the design in further manufacture. They identify the following steps as producing 'an independent article which is not the thing that came out of the claimed process'—
1. Incorporation of the cutting structure CAD file into a larger overall CAD file including bearings and legs;
2. Production of engineering specifications, bills of materials, manufacturing drawings, tooling lists, CNC programs;
3. Manufacture of the legs, a complex process in itself;
4. Manufacture of cones with milled teeth including the steps of forging, rough boring, external machining, shot-blasting, case-hardening, grinding and turning— the complexity of milling a cone with integral teeth can be seen immediately from the figure on for example page 10 of Halliburton's inspection report, which is a Pro/E display showing what the result should look like;
5. For cones with machined inserts, the like complexity, with the addition of drilling the holes and pressing them in;
6. Finally, cleaning, greasing and assembly of the legs, followed by insertion of ball bearings and the plugging of the hole, and welding together of the legs.
- I do not think that it is sensible to view manufacture and design as in some way resulting in separate products. Design is no doubt interesting in the abstract, but when it is used it cannot be divorced from the article made to it. The Registered Designs Act 1949 and its predecessors encouraged lawyers to consider a design as something complete in itself and distinct from any article, but from the point of view of a bit designer the design exists only as a depiction of a bit that is to be made and used. There is no doubt that the criterion with which the claimed method is concerned depend upon the bit shape as a whole (I shall discuss this further when I consider insufficiency) and it follows, it seems to me, that there is no intermediate between this method and the resulting bit, which is as much the direct product of the design process as it is the product of the manufacturing process of which the design is part.
- I should add that the EPO's great reluctance to grant 'product by process' claims on the unchallengeably logical basis that novelty cannot be conferred on an old article by making it according to a new process encourages me to give section 60(1)(c) an interpretation that goes as far as a product by process claim might go, but no further. To the extent that these claims do relate to a mere method of designing divorced from manufacture, they are too wide for reasons I discuss below, but the cure is in my view straightforward.
The IDEAS software in use
- There is a detailed description of the allegedly infringing software in the Product and Process Description (PPD) produced by Smith. Halliburton conducted an inspection of the software in operation, and this resulted in an inspection report. These are both substantial documents, and it would be pointless to précis them here. Although Halliburton say that the inspection made much clear that had been obscure in the product description, the deficiencies were not brought home. Dr Huang, who designed the software on the basis of Dr Ma's work, deposed to the accuracy of the PPD and was not challenged. I shall return to Dr Huang's evidence below. On top of Dr Huang's unchallenged evidence, Mr Portwood, Smith's senior bit designer until 1999 and Project Manager thereafter, gave evidence that the PPD accurately recorded the way in which Smith's bit designers used the software available to them. Smith design and manufacture their drill bits as follows.
- The design of a bit is divided into three phases, referred to as the Baseline phase, the IDEAS Software phase and the Designer Input phase.
- The Baseline phase starts when the designer of the bit receives a document called a Product Development Plan (PDP) which contains a field engineer's statement of requirements for the bit. It includes particulars of the rock for which the bit is intended (the target formation), the intended WOB, the rotational speed range in RPM, the depth at which the bit is to be used and a statement of the objectives to be achieved by the bit in terms of rate of penetration (ROP)—a key parameter—and durability in terms of footage.
- On the basis of the PDP a nearest existing bit is selected (it may be identified in the PDP) and the CAD file for that bit obtained. A file called the 'insert/rock' file is also obtained.
- The insert/rock file contains data specifying how the chosen insert interacts with the specified formation. As I have explained above, inserts come in shapes lying between two basic shapes, chisel and rounded top, and it is necessary to know how the specified type of insert interacts with the formation for which it is intended. The data is obtained by studying the behaviour of the insert as it is pressed into a sample of the specified formation and as it is scraped through the sample formation, all at a confining pressure appropriate to the depth at which the drill will be drilling. If there is brittle fracture, a further study of the resulting craters and their size is performed. For a given PDP an appropriate insert/rock file may already be available, or it may have to be generated.
- The second phase of the drill bit design is the IDEAS software phase. The purpose of the IDEAS software is to simulate the action of a specified bit in a specified formation. The inputs to the software fall into three classes: (a) geometric, describing the bit and its inserts; (b) the insert/rock file; (c) the specified drilling conditions (WOB and RPM) and (d) the simulation conditions.
- Initially, the geometric data is generated from the CAD file for the baseline bit. The insert/rock file is described above. The drilling conditions are derived from the PDP. The principal simulation condition is the angle through which the drill is turned between each step of the simulation and the number of such steps. Finally, an estimate of the cone to bit speed ratio is provided.
- It will be recalled from the discussion of the patent above that the cone to bit speed ratio is not a straightforward quantity to calculate, because of the complexity of the interactions of the inserts with the formation and the offset of the cones, which produces a scraping movement. Paragraph 21 of the PPD describes in detail the manner in which the cone to bit speed ratio is recalculated in each step of the simulation.
- The algorithms used to compute the forces acting on the individual teeth through each step are not described anywhere in the evidence (I believe that Professor Newland is unaware of them) but it is clear that they are complex.
- The Designer Input phase of the process involves the use by the designer of the very extensive data that is output by the simulation to change the design of the bit. The designer's contribution is described in part C of the PPD (paragraphs 54 ff). There may be many iterations with intervening design changes. The IDEAS software permits certain changes to the design of the bit to be made without recourse to the CAD software[7], but of course those changes will have to be transferred to the CAD software before the CAD files are used to manufacture the inserts, cones and bit.
- So far as the Force Balancing patent is concerned, the relevant part of the PPD is ultimately Annexes 1 and 2, which contain a print out of from the IDEAS program which summarises the calculations carried out in a simulation. There is one parameter, called Fz_aver, for each cone (see the top of page 52 for the commented version). Fz_aver is a calculated quantify that represents the average force on a cone over the simulation (30 rotations). Similar information is conveyed by Figures 28, 29 and 30, which show displays produced by IDEAS. In Figures 28 and 29 the vertical axis denotes the percentage of time each cone was subjected to the force specified along the horizontal axis of the plot. The 'box-and-whisker' plot of Figure 30 shows the median (not mean) value of the force, together with an indication of the spread of the forces through each step of the simulation.
- Necessarily, if at any point in time there is no force acting on a cone, that fact will not figure in the computations of Fz_aver, which is derived only from data obtained when there was such a force. Obviously, however, Fz_aver is of sufficient importance that it is reported on the calculation summary sheet. Smith decline to rely upon the fact that it may not be a true average, in the sense that there may be moments when there is no force acting on a cone and those moments do not go towards computing Fz_aver. That there may be such moments appears from the box & whisker plot at Figure 32.
- As will be apparent, the data provided to the designer by IDEAS goes far beyond Fz_aver, and extends (for example) to instantaneous components of forces acting on the individual teeth, the rows and the cones in the radial direction (along an axis in the plane of the hole bottom), the axial direction (in the sense of hole axis) and tangential direction (in the sense of normal to the radial direction), the time averages and the histories of those forces. The PPD indicates that there are ten types of data output which the designer may choose to view (see paragraph 32 and the ensuing explanation of each of the ten types of data).
- The choices made by the designers may therefore be driven not exclusively, or even principally, by a desire merely to achieve equality in the axial forces acting on the cones. The principal desire is to produce a bit having the desired ROP under the conditions specified to the designer in the PDP. A good description was given by Amardeep Singh, who has considerable experience in designing bits using IDEAS. He gave the following unchallenged evidence in respect of a bit referred to as the 'Singh/11' bit, which was promoted and sold as force-balanced.
'14. As 1 have explained, my objective in producing this design was to create a bit that could compete effectively with an existing Hughes product. I identified that the Hughes product had a weakness in the gage row [the outermost row on each cone]. In order to design around this weakness I identified the following (in decreasing order of importance) as optimization criteria for my design:
• Gage Forces;
• Gage Scraping Distance;
• ROP; • Fz Inserts; and
• Cone Balance.
15. I set out my optimization criteria in a Power Point presentation which I gave at the design review meeting which the design team normally holds to discuss new designs. A copy of that Power Point presentation is attached marked Exhibit "AS-6". The first of my criteria was to optimize the forces acting on the gage row of each of the cones of the bit. It can be seen from the charts on page 13 of the Power Point presentation that compared to the 15 MFD and the GFi18 bits, the forces acting on the gage rows on my new design were much lower. The second criterion was to optimize the scraping distance that was covered by each of the gage rows on my design. Page 14 of the Power Point presentation demonstrates that I was able to even up the distance (and therefore the amount of work) that each of the 3 gage rows covered in my new design. My third criterion was ROP. As page 15 of the Power Point Presentation clearly shows, my new design had a much faster ROP in the Leuders Limestone than the comparator bit. It also performed marginally faster in the Carthage Marble than either the 15MFD or the GFi18. My fourth criterion was to optimize the Fz force on each of the inserts of my bit. I was attempting to create a design where the highest force acting on any one tooth at any one time was lower than any of the baseline or comparator bits that I had investigated, in order to avoid insert breakage, particularly on the drive rows of the bit. The drive rows are essentially the 'middle' rows on the cone in between, but not including, the gage row and the nose row. Finally, my fifth optimization criterion was to balance the cones on the bit that I designed. By this I mean that, to the extent possible without detracting from what I had achieved for the other more important criteria, I was attempting to balance the Fz forces acting on the cones of this bit. However, this was only one of my optimization criteria. In fact it was the least important of the five criteria that I identified and, as with all the design work on bits, the final design was a compromise, trying so far as possible to achieve my various goals. As a result it is difficult to quantify how well I achieved my goals and, in particular, this last one.
16. Unfortunately I cannot remember which cutting structure I used as my starting model in Pro/E when I created this design. However, I think that I probably used the cutting structure design for the GFi18 as my start point, and then made alterations to that in order to create my new design. As far as I recall, the changes that I made to my starting design were made in Pro/E. I do not remember whether I used 1ayout.tk at all.'
- He explained this further in cross-examination (Transcript 1277-8):
3 Q. We have seen that one of your optimization criteria was to
4 balance the Fz forces as indicated in the product and process
5 description. When you were designing the 174GXI, that was one
6 of your criterion.
7 A. Yes. Obviously, as everyone understands by now, balancing the
8 forces on the cones is not going to hurt anything. To an
9 extent, yes, that has been one of my criterias when
10 I designed. It is not always the most important criteria. On
11 a mill tooth bit, my Lord, typically you are drilling a soft
12 formation; so the key there is how fast you can drill. They
13 do not drill for too long, there is not too much wear on the
14 bit, so all the other factors that you are looking at cannot
15 sacrifice the ROP. You are trying to compromise between ROP,
16 the forces on the cones, forces on the teeth, and so on, but
17 the predominant factor on a mill tooth bit is ROP because you
18 want to drill fast.
19 In the end, you have to land up feeling happy about
20 a compromise that you made, that, OK, the forces on my cones
21 are 38%, 29%, close enough, but my ROP is 20 % faster. Now
22 I would not drop my ROP or sacrifice it to be 15% faster in
23 order to get my forces to be 33, 33, 33. That would not make
24 any sense for that specific bit. Yes, I would look at the
25 forces on the cones, but that would not - not at the expense 2 of ROP, or some of the other factors that I was looking at.
- Mr Portwood gave rather similar evidence (transcript 1210):
8 Q. There are a number of internal Smith documents stressing that
9 force balancing, that is the Fz force one was talking about,
10 has an optimization criteria. Would you agree that it was
11 known amongst the Smith designers that when designing
12 a criteria, an important criteria was to attempt to force
13 balance the Fzs?
14 A. Again, I guess you have to go back to the deposition. It
15 depends on the application of the rock that you are drilling.
16 Also you are talking about a prior art pre-IDEAS design or
17 IDEAS design?
18 Q. I am talking about IDEAS designs.
19 A. Yes, it just depends. For softer rock, maybe it is not a good
20 idea.
- This evidence, taken with the fact that in some cases a designer will simulate a bit under more than one set of conditions of WOB, RPM and formation, gives rise to a real problem in relating the words of the claim to the real world. While I have attempted to interpret those words in their context in the specification, their application to a real-world bit design provokes a number of questions. Most important is the significance of the iteration of the design adjustment and simulation cycle 'until substantially the same axial force will act on each cutting structure when the bit is drilling into a formation'. On the footing that the words 'substantially the same' must be construed as importing the same numerical limits as are found in claims 6 and 7, is the designer to iterate until the desired condition is achieved in every set of conditions, or only in one?
- The rival considerations are easy to summarise. In support of the contention that the bit should be balanced under all simulated sets of conditions, the specification suggests in the section entitled 'Evaluation of a Force Balanced Roller Cone Bit' (paragraphs [0042]-[0043]) that WOB, along with axial force and cone moment, is a separate optimization objective. The specification is very coy about RPM. The claim is general and therefore the bit must be balanced at least for the conditions in which it was simulated. In support of the contention that balance under one set of conditions is enough, it is said that it is immediately obvious that bits may not in fact be balanced in real formations in any event. Accordingly once the requirement of a balance is achieved in accordance with the claim under one set of conditions, it makes no sense to require balance to the same extent, which might well affect the balance already achieved, under other conditions.
- I consider that the correct answer is probably the second, that balance under one defined set of conditions only need be demonstrated. This discussion demonstrates, if it were not already clear, that the disclosure of this patent is quite inadequate to resolve questions which obviously arise on the claims once the common general knowledge in relation to the daily use of bits is taken into account: does the bit have to be balanced in all formations for which it is sold or for which it is used or for which it is simulated, or for what? The specification provides little assistance.
- I should add that the understanding common between the parties that the balance condition of claim 3 cannot sensibly be given a wider meaning than the numerical limits of claims 6 and 7 is correct. There is no dispute that there is no criterion available outside the specification by which to judge substantial balance, since the measurements were not available in the prior art, and the specification does not suggest an external criterion: compare Cleveland Graphite v Glacier ('thin and flexible') where the criterion was provided by the prior art.
Infringement of the Force balancing patent—the particular bits
- There are a large number of bits (over one hundred) that Halliburton considers infringe this patent. In order to cut down the scope of the trial, I ordered each side to nominate four bits. Smith nominated two different bits made to the same design, another example of which was nominated by Halliburton, with the result that only six distinct designs need to be considered. The bits in issue were inevitably referred to by different names from time to time, and I have endeavoured to give that name. The following list contains the various bits, the numbers by which they are known to Smith, the name of the designer and any name by which the bit was referred to at trial:
(a) 122 GFi18SD: Amardeep Singh: the Singh/18 bit.
(b) 160 GXiV/160MGXi: Scott McDonough: MM8355, MM4541 and MM3439: the McDonough bit.
(c) 174 GXiV: Amardeep Singh: Singh/twist bit.
(d) 084 FGSi30ODV: Dennis Cisneros/Joshua Gatell: the Cisneros bit.
(e) 122 GFi11YV: Amardeep Singh: the Singh/11 bit.
(f) 160 MGS05V: Gary Portwood: the Portwood bit.
- One can start with the proposition that force balancing was promoted by Smith as an advantage of their bits, both in respect of the 'Twist and Shout' range (the Singh/twist and McDonough bits) and the others. This is not to be ignored, since the fact that Smith considered that they were justified on the basis of their design process in calling attention to this feature of the bits is some indication that this aspect of the bit was among the objectives of the design process.
- The McDonough bits. Nothing now turns on the different bits themselves, since they all have the same cutting structure (for illustrations, see section ii of the Halliburton inspection report). There were two sets of simulations, one at 20 000 lbf and one at 35 000 lbf. Fz_aver was 37.7/31.2/31.1 at 20 000 lbf and 35.46/32.7/31.8 at 35 000 lbf. The simulation was in Wellington Shale, and the bits were in fact used throughout the simulated range. His evidence