HALLIBURTON ENERGY SERVICES, INC. v (1) SMITH INTERNATIONAL (NORTH SEA) LIMITED (2) SMITH INTERNATIONAL, INC. (3) SMITH INTERNATIONAL ITALIA SpA [2005] EWHC 1623 (Pat)

'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.'

'[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.'

'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.'

'[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.'

'[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.'

'[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).'

'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.'

'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. where V 3d0 is the volume matrix of the initial designed bit (before optimization). V 2d0 is obtained from the rock bit computer program by simulate the bit drilling procedure at least 10 seconds [ sic ]. V 2d0 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 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.'

'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.'

'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.'

"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 "

"the kind of meticulous verbal analysis which lawyers are too often tempted by their training to indulge."

'12 Q. All right. It was just .... You were also, while using IDEAS, 13 attempting to balance the Fz force on the cones as one of the 14 criteria. 15 A. Yes. 16 Q. Your bit, as I understand it, and we have the details, you ran 17 it with different parameters, the final design, what you 18 believed to be the final design. For some parameters, it was 19 better balanced than others. Is that right? 20 A. Yes. '

'The subsection is concerned with the disclosure of the invention in the specification. Thus it is necessary to read the specification through the eyes of the skilled addressee to ascertain what is the invention that is disclosed. Even where patents relate to articles, the inventions disclosed in difference specifications can be different in kind. For example, the invention disclosed may relate to an article which will perform a particular function or an article which is cheaper to make that similar articles. In the latter case, it is the very essence of the invention disclosed in the specification that the article can be made more cheaply and therefore too perform the invention the person skilled in the art must be able to make the article cheaply as described in the specification. In the former case, the person skilled in the art must be able to produce the article which will perform the function, as that is the invention disclosed. The section requires the skilled man to be able to perform the invention, but does not lay down the limits as to the time and energy that the skilled man must spend seeking to perform the invention before it is insufficient. Clearly there must be a limit. The subsection, by using the words "clearly enough and completely enough," contemplates that patent specifications need not set out every detail necessary for performance, but can leave the skilled man to use his skill to perform the invention. In so doing he must seek success. He should not be required to carry out any prolonged research, enquiry or experiment. He may need to carry out the ordinary methods of trial and error, which involve no inventive step and generally are necessary in applying the particular discovery to produce a practical result. In each case, it is a question of fact, depending on the nature of the invention, whether the steps needed to perform the invention are ordinary steps of trial and error which a skilled man would realise would be necessary and normal to produce a practical result. The section requires the skilled man to be able to perform the invention. Such a man is the ordinary addressee of the patent. He must be assumed to be possessed of the common general knowledge in the art and the necessary skill and expertise to apply that knowledge. He is the man of average skill and intelligence, but is not expected to be able to exercise any invention. In some arts he may have a degree, in others he will be a man with practical experience only. Further, in circumstances where the art encompasses more than one technology, the notional skilled person will be possessed of those technologies which may mean that he will have the knowledge of more than one person.'

'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.'

'16 Q. Yes. You break it down into vertical matchsticks. As far as 17 those concerned, if they are in contact with the rock, then 18 you use those to calculate the forces from equations 1, 2 and 19 3, do you not? 20 A. Well, as I understand what this model does, and beginning 21 initially with equation 1, it takes a matchstick of elemental 22 size Sc. It does not give any information as to what 23 that area is. It says it is a cross-section on the XY plane. 24 I understand that. It does not tell you how big it is, 25 whether large, small or infinitesimal. It does not appear to 2 come into the resulting calculation, nor does the length LE, 3 along the Z axis. This force formulation seems to say that 4 the vertical force is in proportion to the depth of 5 penetration SE to the rock parameter s, which 6 is defined as the compressive strength of the rock, and 7 a parameter ke associated with the formation 8 properties. 9 I think it must be true, must it not, that on any 10 analysis ke must depend on the area Sc and will not be 11 a property of the rock per se but the property would be 12 something to do with the size of the matchstick. At any rate, 13 the formulation says that the vertical upforce on the 14 matchstick is in proportion to its depth of penetration and 15 that you can assemble a bundle of matchsticks into a complete 16 tooth and you will then have an accurate model or 17 a satisfactory model of the upthrust on the tooth. I have not 18 seen any evidence that that is a correct realistic 19 formulation.'

'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. '

'In this paper, the surface of each tooth of roller bits is represented by scores of points, whose 3-D compound coordinates are used to reflect the shape and size of the tooth. Thus the cutting structure of the bit together with their movement is represented by the time-sequence of the coordinates of the several thousand points. Hence, the computer simulates the roller bit.'

'Up to, now, however, all the bit's motion models, the interacting force models, the ROP and torque models of roller bits are obtained by simplifying the interaction between the bit and bottom hole. The major simplifications and suppositions are: (1) without any regard to the shape and size of the tooth by using a point or a line of the tooth; (2)'

'(1)The position of the bit cutting structure and the relative position of the teeth in space. (2)The shape and size of the bottom hole and the well bore. (3)The interacting factors such as the contacting teeth of the bit, the number of the contacting teeth, the inserted depth of each tooth, the shape and size of the inserted part of each tooth. (4 )The size and direction of each interacting force. (5)The shape and size of a crater by any contacting tooth. (6)The torque of the bit and the size and direction of the resultant lateral force. (7)The deviation and the lateral displacement of the bit.'

'Compared with the conventional methods (design, manufacture, test and repeating the circle), to develop a new type of roller bit, this software can save a lot of expenses and time.'

'In view of bearing loads it would therefore be desirable to have a bit with the same button pattern on all rollers. Each roller would then absorb the same amount of the feed force and all three rollers would be subjected to the same bearing toad But the demand for the largest possible rollers can be better met by provision of different button patterns. '

'In redesigns and new designs of roller bits it has proved necessary already on the drawing board to get some idea of the force balance on the bit, both that among the three rollers and that between individual bearings in anyone roller. This is done in a miniature computer of type PDP 11 by means of two simulation programmes specially prepared for roller bits. The FORTRAN programming language is used for this purpose. There is naturally an effort to achieve as good an agreement as possible between the simulation models and the bearing force measurements on the rig. The most difficult thing with the models is to describe as correctly as possible the play of forces between the cemented carbide button and the rock, how great the force is, in which direction it works, etc. In order to get an idea of the magnitude of the bearing forces and their variation during rotation of the rollers, the bearing forces were previously projected on the drawing board geometrically for each 15º which the roller was turned. This was a time-consuming method and it took several weeks to draw one's way through the three rollers on a bit. The corresponding work can now be performed in a few minutes with the aid of a computer. Today, it takes five minutes to calculate interval moves of 5º on the three rollers of a 250mm bit,. In this way a large number of alternative solutions can be calculated in order to arrive at the alternative which best satisfies the stipulated requirements.'

'drill bit operation provides an equal distribution of the load on all bearings by means of the rows breaking up circular bottomhole areas that are identical in area.'

' 4.— (1) Subject to subsection (2) below, an invention shall be taken to be capable of industrial application if it can be made or used in any kind of industry, including agriculture. (2) an invention of a method of treatment of the human or animal body by surgery or therapy or of diagnosis practised on the human or animal body shall not be taken to be capable of industrial application. (3) Subsection (2) above shall not prevent a product consisting of a substance or composition being treated as capable of industrial application merely because it is invented for use in any such method.'

'1. A method of designing a roller cone bit, comprising the steps of: (a) adjusting the orientation of at least one tooth on a cone, in dependence on an expected trajectory of said tooth through formation material at the cutting face, in dependence on an estimated ratio of cone rotation to bit rotation; (b) recalculating said ratio, if the location of any row of teeth on said cone changes during optimization; (c) recalculating the trajectory of said tooth in accordance with a recalculated value of said cone speed; and (d) adjusting the orientation of said tooth again in accordance with a recalculated value of said tooth trajectory.'

'Calculating cutting depth, area, volume and forces for each [tooth] in cutting, Updating the hole bottom matrices based on the crater model for rocking being [drilled]. [Counting] the number of teeth […] cutting for cones and bit [in] any time step. Projecting the teeth force into cone and bit coordinates and getting the total cone and bit forces and moments. Calculating the specific energy for the bit.'

'A method of designing a roller-cone bit, comprising the steps of: (a) adjusting the orientation of at least one tooth on a cone, in dependence on an expected trajectory of said tooth through formation material at the cutting face, in dependence of an estimated ratio of cone rotation to bit rotation; (b) recalculating said ratio, if the location of any row of teeth on said cone changes during optimization; (c) recalculating the trajectory of said tooth in accordance with a recalculated value of said cone speed; and (d) adjusting the orientation of said tooth again, in accordance with a recalculated value of said tooth trajectory.'

'10. I cannot remember exactly what 1 looked at in lDEAS when I designed this cutting structure. However, I would have looked at the "insert" output for each row of each cone in the analysis phase of IDEAS because the teeth on my design were oriented. Although I cannot remember doing so, I would have probably attempted to ensure that the red areas (indicating contact with the formation) were not concentrated in one small area on the output, by rotating the tooth to ensure that contact with the formation was distributed across as much of the tooth as possible. 11. I may also have viewed the 'bottom hole plot' and the 'animation' design tools within IDEAS. The animation tool shows the cutting structure design in rotation, and can assist in detecting gross design issues and errors in the design process. For example, if I had made a mistake in translating my design from Pro/E to IDEAS that mistake could be quickly detected by looking at the animation. Predominantly, this would be my reason for pulling up the animation window. This window also allows the user to visualize occurrences of tracking. However, it would require the user to watch the simulation with a close eye throughout the entirety of the simulation in order to understand whether a tooth is tracking often enough to warrant alteration, so I did not think it was the best means for detecting tracking and altering tooth orientation. I would not have used the animation window to alter tooth orientation on my design. The bottom hole plot can also be used to detect tracking but is not very useful for determining tooth orientation. If tracking were to occur on one or more of the rows, then a pitch break may have been added to prevent this from happening. I would have relied upon the "insert" output as means for altering tooth orientation. I say this because the "insert" output is more or less a summary of all the occurrences of contact with the simulated formation of all the teeth for a given row. 12. During the design process I would also have looked at the Fz_Aver information for each of the rows and cones as I changed the crest length, orientation, location and/or crest width of the milled teeth, so that I could see how my changes were affecting the ratio of cone load to bit load. This is a difficult task as, more often than not, a design yielding a faster ROP would also yield more unbalanced cones. It is a general assumption by bit designers that if you distribute the forces acting on each cone disproportionately, then one of the bearings of the bit may fail sooner than if they all took the same load. Therefore, I always like to try to get the milled tooth bits that I design to be as close to being balanced as I can manage, while still taking into account the need for as fast an ROP as possible. '

'The Patent provides no or no sufficient disclosure as to how to perform the recited adjustments: how to determine or recalculate the expected trajectory or the relative positions of the bit and formation that would be required; how to estimate or recalculated the recited ratio of cone rotation to bit rotation; how to determine the cone speed; or how to account for the physical aspects of drilling into a formation in particular how to determine and apply the physical properties of the formation and/or the bit.'

'Mr Hall's evidence on torque balance was at Hall I para 34, and Hall II paras 70, 75 and 77. He was XX'd on Day 3 at 439 et seq., more especially from 451. The thrust of his evidence was that: Rate of penetration and cone speed are interrelated. You solve for them by an iterative process. You would initially assume an advance for the bit, and iterate on that to find the rate of penetration. Thereafter, having that, you iterate on torque balancing to check the cone speed. o If necessary, you then go back and iterate penetration again. As to this, see passages starting at 456/15, 457/12, and at 460:'

'the patented program for optimizing the tooth (or insert) crest direction has great interest for the bit designer, manufacturer and user. If the tooth or insert is not symmetrical about its own center line, its crest is in a certain direction. This direction has considerable effect on the scraping area and the rock breaking effectiveness of the bit. This direction, however, was formerly always along the generatrix [i.e. parallel to the axis] of the roller cone, until the new type of bit was designed by the author's research group. The ROP of these bits with the optimised tooth deflection angle are much improved in the field tests.'

"[0030] The following patent application 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. That application which has common ownership inventorship and effective filing date with the present application is Application no. filed 31 August 1999 entitled "