Western Oilfield Equipment Rentals Ltd. v. M-I LLC

Western Oilfield Equipment Rentals Ltd. v. M-I LLC
Court (s) Database
Federal Court Decisions
Date
2019-12-23
Neutral citation
2019 FC 1606
File numbers
T-1056-15
Decision Content
Date: 20191223
Docket: T-1056-15
Citation: 2019 FC 1606
Ottawa, Ontario, December 23, 2019
PRESENT: Mr. Justice James W. O'Reilly
BETWEEN:
WESTERN OILFIELD
EQUIPMENT RENTALS LTD
Plaintiff
(Defendant by Counterclaim)
and
M-I LLC
Defendant
(Plaintiff by Counterclaim)
AND BETWEEN:
M-I LLC
Plaintiff by Counterclaim
and
FP MARANGONI INC
Defendant by Counterclaim
PUBLIC JUDGMENT AND REASONS
(Confidential Judgment and Reasons issued December 23, 2019)
Table of Contents
I. Overview 4
II. Factual Background 5
A. Issue One – For purposes of construing the ‘173 patent, who is the person skilled in the art? 10
B. Issue Two – What is the proper construction of the ‘173 patent claims in issue? 11
(1) The ‘173 Patent 11
(2) Essential Terms used in the Patent 18
(a) “Slurry” 18
(b) “First Screen” 20
(c) “Vapour” and “Hazardous Gases” 24
(d) “Enhancing Flow” 25
(e) “Controlling Air Flow” 26
(f) “Conveying All of the Air or Vapour and Drilling Fluid” 27
(g) “Degassing Chamber” 28
C. Issue Three – Have the defendants infringed the claims of the ‘173 patent? 29
(1) The Vac-Screen System 29
(2) Have the Defendants Directly Infringed the Patent? 31
(3) Have the Defendants Induced Infringement by Others? 39
(a) Western’s Business Relationships 39
(b) Inducement 41
(4) Common Design 44
D. Issue Four – Are the claims in issue invalid? 44
(1) Inutility 44
(2) Insufficiency 46
(3) Anticipation 47
(a) Group One – Hensley (2005) and Derrick (2005) 49
(b) Group Two – Vasshus (2006), Manuel (1988), and Schellstede (1987) 53
(c) Group Three – Logue (1949), Ennis (1975), Bongert (1976), Cook (1989), and Fast (1990) 57
(d) Group Four – Rischer (2004) 60
(4) Obviousness 61
(a) The Skilled Person 61
(b) Common General Knowledge 61
(c) The Inventive Concepts 63
(5) Claims Broader 67
(a) Claims Broader than Disclosure 67
(b) Claims Broader than Invention 68
(6) Lack of Reasonable Inferability 69
E. Issue Five – What damages are owed by the defendants to M-I? 74
III. Motion under Rule 227 80
A. Background 81
B. The Issue 81
C. Conclusion 83
IV. Conclusion and Disposition 83
I.
Overview
[1] The plaintiff (by counterclaim), M-I LLC (M-I), alleges that the defendants, Western Oilfield Equipment Rentals Ltd (Western) and FP Marangoni (FPM), have infringed M-I’s patent (Canadian Patent 2,664,173). FPM is a wholly-owned subsidiary of Western. In these reasons, I will generally refer to the defendants (by counterclaim) collectively as “Western” unless the factual context requires otherwise.
[2] M-I maintains that Western has infringed the ‘173 patent directly and has also induced infringement by others, and seeks damages and compensation. In response, Western asserts that the ‘173 patent is invalid on numerous grounds, including inutility, insufficiency, anticipation, obviousness, and overbreadth.
[3] I find that M-I has made out its infringement claim. I also conclude that none of the defendants’ invalidity allegations are supported by the preponderance of the evidence. M-I is, therefore, entitled to damages and compensation.
[4] After laying out the general facts and background to this action, I will address the following issues:
For purposes of construing the ‘173 patent, who is the person skilled in the art?
What is the proper construction of the ‘173 patent claims in issue?
Have the defendants infringed the claims of the ‘173 patent?
Are the claims in issue invalid?
What damages and compensation are owed by the defendants to M-I?
[5] In addition to these issues, I include my decision on a motion brought by M-I during the trial under Rule 227.
II. Factual Background
[6] This case relates to a machine called a “shale shaker”. Shale shakers are used in the oil and gas industry to remove solids from the drilling fluid that emerges from an active well, so that the fluid can be reused. The solids are the product of the drill bit cutting through rock. They are often referred to as “cuttings.” Drilling fluid provides a medium for sending the cuttings to the surface, and helps lubricate the drilling equipment. The combined solid and fluid mixture that comes to the surface at the drill site is called “slurry.”
[7] In essence, a shale shaker operates like a vibrating sieve, receiving the slurry and screening out the cuttings within it, leaving the fluid to be captured by tanks below. Since drilling fluid is expensive, the more proficient a shaker is in removing solids, the lower the cost of the drilling operation. The more reusable drilling fluid recovered, the better.
[8] In the mid-2000s, M-I was working on improved shale shaker technology. A mechanical engineer at M-I, Mr Brian Carr, along with 30 other engineers, was involved in researching and developing shakers and screens. At that time, the process at M-I for developing a new product involved a number of successive steps – a feasibility study, detailed design, field testing, and commercialization. New ideas were presented to M-I’s Product Development Council, which determined whether a product would move from one stage to the next.
[9] Mr Carr presented his preliminary idea for a new shaker model to the Council in 2005. One of his ideas was to apply a vacuum to the shaker screen in order to recover more fluid. He made a fuller presentation the following year, describing his objectives as being to remove low-gravity solids from drilling fluid, minimize the amount of drilling fluid left on solids, and recovering drilling fluid before it spilled over the end of the shaker. He expressed his ambitious hope that a product could be commercialized within 18 months.
[10] The Council approved Mr Carr’s proposal, giving him 30 days and a dedicated team of 5 or 6 members to develop a feasibility study. That study included assessment of a vacuum-assisted shaker with an integrated vibrating sump and a means of controlling air flow to prevent stalling of solids on the screens. A prototype was built within the same time frame. Mr Carr estimated that he would need another 3 months and a budget of $226,400.00 to continue.
[11] Mr Carr’s prototype included a vacuum at the feed-end of the shaker, that is, at the point where the slurry entered the shaker. The shaker had a total of four screens. It was tested under various scenarios – flooding the entry screens with slurry, partially covering the entry screens with slurry, removing the two screens at the discharge end of the shaker so that the vacuum was applied to the two screens at the entry point, applying a steady vacuum, and applying a pulsing vacuum. Overall, the results were positive. The vacuum enhanced the amount of fluid pulled through the screens by 50% and the cuttings coming of the end of the shaker were dryer. One problem was that the vacuum pulled mist as well as liquid through the screen, which tripped the pump, so a means of separating air from liquid was required. A simple solution of using a “rig-vac”, essentially a commercial version of a household wet-vac, was proposed.
[12] At the end of the feasibility stage, Mr Carr recommended moving forward with the vacuum-assisted shaker with field tests to be completed within 5 or 6 months. At that point, on October 1, 2007, M-I filed its provisional patent application. The ‘173 patent issued on June 16, 2015.
[13] In due course, M-I released a new commercial shaker but it did not include a vacuum system. Still, the ‘173 patent and its United States counterpart included a vacuum element.
[14] Some six years later, Mr Carr became aware of FPM’s Vac-Screen System (VSS), a means of recovering drilling fluid from a shaker through use of a vacuum. Some of his colleagues did not believe it was a viable technology, but considered working with FPM if its technology was patented. There was some ensuing contact between M-I and FP USA, FPM’s US affiliate, about this technology.
[15] Mr Calvin Carter, Business Development Manager at M-I, recalled seeing the VSS in 2013, including in Canada. He regarded it as virtually identical to M-I’s own “Maximizer” machine, which M-I’s subsidiary, M-I Swaco, had an agreement with FP USA to rent out under a 60/40 shared revenue arrangement beginning in 2011 or 2012. They called the system “FP Maximizer.” Under the agreement, whichever company supplied the vacuum, the hoses, and the trays got 60% of revenues and the other company got 40%. This product was never offered in Canada. However, M-I has a licence agreement in Canada with a company called FourK Energy Services for a similar product called the “Scavenger”.
[16] Mr Al Imler, formerly a Western employee, described the origins of the VSS. In 2010, he was working with Mr Dan Pomerleau at a company called EDSI. They noticed that a lot of drilling fluid was flowing over the ends of shakers and set about to solve that problem. They developed a system that consisted of a tray inserted at the discharge end of a shaker with a vacuum applied to the screen. Mr Imler stated that the apparatus of the VSS was “firmly attached” to the shaker; otherwise, it would break. It was essentially part of the shaker. From early on in the development of the VSS, valves were included in order to regulate the amount of suction applied to the screen to prevent stalling.
[17] When EDSI started going out of business, Mr Imler and Mr Pomerleau created FPM as a company devoted to renting out the VSS. Mr Imler was FPM’s Operations Manager. He designed the trays, and was in charge of installing the system. In 2012, FPM was purchased by a holding company called 32 Degrees Capital, which also owned Western (beginning in 2011) and another company called Markwater Handling Systems. FPM continued to rent out the VSS. The following year, Western became the operating arm of the company and rented out the VSS in place of FPM.
[18] Mr Jeff Cooke began working in 2013 for an equipment rental firm called Richfield Equipment Limited (Richfield). According to Mr Cooke, Richfield had an unwritten business relationship with FPM, which was developing a vacuum system for recovering drilling fluid through screens. At the time, FPM did not have a name for its product, but Mr Cooke began referring to it as the Vac-Screen, a name that stuck. Richfield’s work with this product began in late 2010 and ended in March of 2014.
[19] Richfield’s role was to install and service the equipment and rent out vacuums and other components as required. It billed the oil companies and then passed along FPM’s share once the invoices had been paid. Mr Cooke explained that this billing arrangement simply ensured that Richfield got paid up front.
[20] Within this business relationship, FPM brought in virtually all of the clients. Installation of the VSS included explaining to the crew how the system worked and what their responsibilities were. The system included valves for adjusting the air flow to prevent stalling on the screens, which the drill crew was responsible for controlling. If there was any problem, Richfield would be called in to deal with stalled screens, usually because the rig crews had not followed the initial instructions or needed to be reminded of them.
[21] In essence, the VSS involves an add-on feature for shale shakers available in the market. It involves attaching an additional screen, connected to a vacuum, to the discharge end of a shaker and is intended to remove any remaining liquid adhering to the solids that have already passed along the shaker’s screens. The VSS does not itself include a vacuum; rather, it relies on commercially-available equipment to complete the system. According to Mr Cooke, the VSS includes valves for venting the vacuum to adjust the air flow. Mr Carter testified that the VSS employs a means of controlling air flow by way of what he called a “snorkel valve”.
[22] Between them, the defendants (by counterclaim) have offered the VSS for rent in Canada since 2010.
A. Issue One – For purposes of construing the ‘173 patent, who is the person skilled in the art?
[23] The parties do not disagree substantially on the definition of a notional skilled person. M-I’s expert, Mr Robert Palmer, described the skilled person as someone with at least five years’ experience in the application, operation, and design of shale shakers. (A summary of the experts’ qualifications is set out in an Annex.)
[24] Mr Peter Matthews, for Western, stated that the skilled person would have an engineering degree or equivalent, and three years’ experience with shakers.
[25] Mr Benard Murphy, another of Western’s experts, essentially agreed with Mr Matthews. Mr Murphy regarded the skilled person as being someone who had experience designing manufacturing equipment such as shakers, separators, degassers, and cyclones; someone with a mechanical engineering degree with three or more years of experience in the field, or someone without a degree but possessing more experience in the area.
[26] In my view, the skilled person for present purposes is someone with five years’ experience in the application, operation, and design of shale shakers. I do not see the need for the person to have a degree in engineering. The patent relates to a variation on a piece of technology that was well-known and widely-used in the oil and gas industry. The patent is addressed to persons who would be familiar with that technology and would understand the improvements that the patented method and system were intended to provide.
B. Issue Two – What is the proper construction of the ‘173 patent claims in issue?
(1) The ‘173 Patent
[27] The ‘173 Patent is entitled “Shaker and Degasser Combination”. M-I owns the patent; Mr Carr is the sole named inventor.
[28] The underlying application was filed on October 1, 2007 and was amended on October 2, 2013, January 28, 2014, August 27, 2014, and November 4, 2014. Some claims were added, some were deleted, and some were amended. In addition, some paragraphs were added to the specification. The patent issued on June 16, 2015.
[29] The patent describes the invention as a system for separating components of a slurry. The various elements of the system are listed and include a housing, a basket holding at least one screen, a vibrator coupled to the basket, a sump situated below the basket to collect at least a portion of the slurry passing through the screen, a pressure differential device connected to the sump and providing a pressure differential across the screen, a toggling device for toggling the pressure differential, a degassing chamber situated between the sump and the pressure differential device, and a conduit connected to the degassing chamber for recovery of the degassed fluid.
[30] The background section of the patent’s specification states that the embodiments of the invention “relate generally to shale shakers and screens” and, more specifically, to “a shale shaker having pulse-vacuum assisted screening” and “methods and apparatus for removing entrained gases from a slurry.” The background goes on to describe the purpose of drilling fluid in the oil and gas industry, which is primarily to act as a lubricant to cool drill bits. The fluid is conveyed downhole through the drill string and is forced back up to the surface in the annular area between the drill string and the wellbore.
[31] The fluid returns to the surface as a slurry. The patent defines “slurry” as a “mixture of drilling fluid and drill cuttings”.
[32] Before the fluid can be reused, the cuttings must be removed from it. That is the role of a shale shaker. Various types of shakers and their components that were known in the prior art are described in the patent.
[33] The patent then points out one of the problems in the prior art equipment. Sometimes the separation of fluid from cuttings is incomplete, meaning that the cuttings are still wet after passing through the shaker. Other equipment, such as a rotating vacuum dryer, then has to be used to remove the remaining liquid.
[34] One means of making shakers more efficient at removing liquids from cuttings, says the patent, would be to apply a pressure differential through the screen. The patent mentions a shaker disclosed in the prior art that in fact uses a pressure differential applied continuously beneath a screen (Hensley, et al.). The problem with this technique is that the continuous vacuum may cause cuttings to stick to the screen, preventing fluids from flowing through it. Accordingly, the patent cites the ongoing need for more efficient shakers - with an increased fluid capacity, a higher rate of fluid flowing through the screens, and better fluid removal ability, without hindering the flow of solids across the screens. Further, the patent also cites a need for a means of removing entrained gases from the recovered fluid.
[35] The patented system may also involve using a pressure differential generator that would pull air or vapour through the first screen to “enhance the flow of drilling fluid through the first screen with respect to a second screen” to which no pressure differential was applied. The drilling fluid, and the air or vapour, would be collected in an external chamber connected to the pressure differential generator.
[36] The summary also describes a method for separating components of a slurry by introducing the slurry to the top of a screen and toggling a pressure differential across the screen, either by creating a partial vacuum beneath the screen and intermittently interrupting the vacuum or disrupting the flow of recovered vapour. The invention includes a method by which the slurry is introduced to a shaker containing a first and a second screen. The slurry passes over the first screen where a pressure differential is applied and over a second screen to which no pressure differential is applied.
[37] The patent then goes on to provide detailed descriptions of various shakers, for which rudimentary drawings are provided, and related embodiments of the invention. Most of the evidence in this case related to the shakers depicted in Figures 5, 6, and 7 of the patent.
[38] Figure 5 shows “a simplified flow diagram” for one embodiment of the invention (ie, it is not an engineering drawing). The figure shows a basket (102), a screen (104), a sump (106), slurry (108), an inlet (A), and an outlet (B).
[39] The vapour within the sump (112) is connected by way of a conduit (113) and a valve (114) to the pressure differential device (116). The collected vapour could be flared, vented, or recovered by a flow line (122). Fluids (110) would be recovered from the sump by way of a separate flow line (124). The recovered fluid could be degassed by the pressure differential created by the device (116).
[40] Figure 6 also depicts a “simplified flow diagram” for another embodiment of the system. This shaker may include a basket (202), a screen (204), and a sump (206). The slurry (208) is fed to the inlet of the shaker (A) and the cuttings are collected at the outlet (B). The drilling fluid is recovered in the sump (206). A pressure differential is created by connecting the sump (206) to a degassing chamber (212) and then to a pressure differential device (216) by way of a flow line (213) and valve (214). The differential pressure results in the collection of liquid and vapour in the degassing chamber (212). The vapour can be flared, vented, or recovered by a flow line (222). The liquid can be recovered by another flow line (224) and sent for further processing. The liquid could be degassed by the pressure differential created by the device (216).
[41] Figure 7 depicts a vibratory separator including a housing (502), an inlet (504), an outlet (506), and multiple, vertically-stacked screens (508). Pressure differential devices can be placed in various locations, including between the screens and the sump, within the sump, or outside the sump. The apertures of the various screens may vary, for example, by having screens with larger apertures at the top and screens with smaller apertures below. The slurry falls onto the screens and is conveyed to the outlet using vibration and pulse-assisted devices. The patent says that vapours, “including any hazardous gases, (eg, hydrogen sulfide (H2S))” can be extracted by way of a fume hood (516). At that point, the vapours or gases can be treated or vented.
[42] The collected drilling fluid could then be directed to a containment area for degassing, using devices known in the prior art.
[43] The patent states that the various embodiments relate to shakers having “increased fluid capacity, increased fluid flow-through rates across the screens, and/or improved fluid removal efficiencies”. In addition, they may provide shakers with “reduced hazardous vapours in vapour spaces” and permit more efficient separation of entrained gases.
[44] The patent contains 23 claims. The first 18 relate to a method; the remainder to a system.
[45] The method involves introducing a slurry to a shaker containing a first screen and a second screen, flowing the slurry over the first screen, and applying a pressure differential to the first screen, but not to the second screen (claim 1). It includes controlling air flow under at least a portion of the first screen to prevent stalling the slurry on the screen (claim 2) and pulling vapours and fluid through the screen to a degassing chamber (claim 10). The claims include a method in which a pressure differential is also applied to the second screen, but where the differential is less than that applied to the first screen (claim 3), or even zero (claim 4). The claims include toggling the pressure differential applied to the first screen (claim 5), intermittently interrupting the pressure differential (claim 6), pulsing the pressure differential (claim 7), or applying a third differential to another portion of the first screen (claim 8). They include use of a vacuum external to the shaker (claim 9). In addition, the method includes applying a differential pressure, created by an external device, between an area above the first screen and below the first screen, and applying a different differential pressure to the second screen (claim 11). The method includes the steps in claim 11 where vacuum pressure is applied only to a portion of the first screen (claim 18), or the collected vapour and drilling fluid are sent to a chamber to be separated (claim 16).
[46] The patent also claims a method in which air or vapour, and the drilling fluid, are pulled through the first screen and conveyed to an external chamber where the air or vapour is separated from the fluid (claim 12), including an external degassing chamber (claim 17), even if the vacuum pressure is applied only to a portion of the first screen (claim 18).
[47] The claimed method may also involve the procedures described in claims 10 and 11 where the pressure differential applied to the first screen is intermittently interrupted (claim 13) or pulsed (claim 14), or applied to a first portion of the second screen (claim 15).
[48] The claimed system comprises a first screen with upper and lower sides for separating cuttings from fluids, and a pressure differential generator that pulls air or vapour through the first screen “to enhance the flow of drilling fluid through the first screen with respect to a second screen”, where the generator does not create a pressure differential between an area above and below the second screen (claim 19). It may additionally comprise a sump below the first screen to collect air, vapour, and fluid, and a degassing chamber collecting “all of the air or vapour and the drilling fluid” and removing air or vapour from the fluid (claim 20). The pressure differential generator may be external to the shaker (claim 21) and adjusted to prevent stalling of drill cuttings on the first screen (claim 22). Finally, the systems described in claims 19 and 20 may include a second pressure differential generator connected to a third screen to create a second pressure differential (claim 23).
[49] M-I’s expert, Mr Palmer, conceded that claims 1, 11, 16, and 19 of the ‘173 patent are invalid on the basis of anticipation (see below).
(2) Essential Terms used in the Patent
[50] A number of terms in the patent need to be construed in order to understand the scope of the claims. The patent must be construed according to the understanding of a person skilled in the art, whom I have described above. Construction of the patent is carried out with the benefit of the opinions provided by the parties’ experts. The following are the essential terms in issue and my construction of them.
(a) “Slurry”
[51] The patent states that, “as used herein”, the term “slurry” “refers to a mixture of drilling fluid and drill cuttings”.
[52] Western submits that “slurry” is not the same as “wet drill cuttings”, another term used in the patent. Western urges me to conclude that “slurry” is the mixture of drilling oil and drill cuttings that enters the shaker, whereas “wet drill cuttings” is the product that exits the shaker after most of the drilling fluid has been removed.
[53] Western’s experts, Mr Matthews and Mr Murphy, both adopted this distinction. Mr Matthews stated that a “slurry” is a suspension of solids in liquids, but the mixture at the end of the shaker is just wet cuttings. However, Mr Matthews conceded that the inventor of the ‘173 patent provided a definition of “slurry” to be used in construing the patent. Further, Mr Matthews accepted that wet drill cuttings are, indeed, a mixture of drilling fluid and cuttings.
[54] Mr Murphy agreed that a slurry is “a combination of the liquid drilling mud and solid drill cuttings.” However, he was adamant that the combination of fluid and cuttings at the discharge end of a shaker was not a “slurry”, notwithstanding the definition in the patent.
[55] I disagree with Western’s submission that “slurry” does not include wet drill cuttings. When the patent uses the term “wet drill cuttings”, it does so only to highlight the problem with the existing technology. It notes that the separation of drilling fluid from solids “is often incomplete, resulting in wet drill cuttings.” I do not read this statement as contradicting the patent’s definition of “slurry”. It is simply specifying a problem in the prior art.
[56] Accordingly, I agree with M-I’s expert, Mr Palmer, that the patent defines a slurry as a mixture of drilling fluid and cuttings, and that that definition must be used to construe the patent. The fact that there is a higher proportion of liquid in the substance entering the shaker than in the substance exiting it does not mean that one is slurry and the other is not. Some slurries are just slurrier than others.
(b) “First Screen”
[57] In the patent’s claims, a pressure differential is applied to a “first screen”.
[58] Western argues that “first screen” means the screen closest to the end of the shaker where slurry is introduced. This is consistent, says Western, with the way screens are numbered in various technical documents and with the usage of the term by skilled persons in the industry.
[59] On the question of what is the “first screen,” Mr Murphy emphasized what that term means in the industry. In his view, “first screen” means the screen at the input end of a shaker. In his view, since the main purpose of the invention is to increase the flow of liquids through the shaker, this can best be achieved by applying a pressure differential at the input end. Therefore, it would make sense that “first screen” means the first screen the slurry meets.
[60] However, he also stated that his interpretation arose “[w]ithout having read anything in the patent.” In other words, he acknowledged, at least implicitly, that the patent might use the term “first screen” in a specific way. Indeed, he ultimately accepted that, in the patent, first screen could be any screen. He originally relied on various statements in the patent confirming his view that “first screen” meant the screen at the input end of a shaker, but all of the references he cited specified the location of the screen that was being referred to. For example, in respect of Figure 3, the patent describes where the first two screens are and where the last two screens are. That would be a superfluous description if it were clear that a first screen was always positioned at the input end of a shaker.
[61] Mr Matthews testified that “first screen” is always the screen closest to the inlet. Since one of the main objects of the patent is to increase the shaker’s capacity, he believed it would make little sense to apply a pressure differential elsewhere than at the shaker’s inlet. Applying a pressure differential to the last screen, said Mr. Matthews, would not increase the shaker’s capacity to process drilling fluids. However, he conceded that adding a pressure differential to the output screen would increase the flow of drilling fluid through that screen as a percentage of the flow through the input screen. (Mr Murphy held a similar view.) Mr Matthews also accepted that the ’173 patent makes clear that a pressure differential can be applied to the screen at the discharge end of the shaker (para 37). Therefore, the term “first screen” cannot refer exclusively to the screen at the input end. In fact, the pressure differential could be applied to any screen. Mr Matthews stated that he had overlooked that part of the patent.
[62] For M-I, Mr Palmer pointed out that the claims require that the shaker have both a “first screen” and a “second screen” (claims 1, 11, and 19). However, there is no requirement that the first screen be closest to the inlet. A skilled person, in Mr Palmer’s view, would understand that the key difference between first and second screens is not location but function. For example, in the description of Figure 3, the invention makes clear that a pressure differential could be applied to the screens closest to the inlet, or the screens closest to the outlet, or both (para 37). Wherever the pressure differential is applied, that is a “first screen” as defined in the patent. Other passages and figures in the patent reinforce Mr Palmer’s construction (paras 44, 45, 59, 60, Fig 4, 7).
[63] Mr Palmer also disputed Western’s assertion that the prime objective of the patent could be achieved only if a pressure differential were applied to the screen closest to the inlet. According to Western, that objective is to increase a shaker’s fluid capacity by drawing a maximum amount of fluid through the screen on the input side. As mentioned, Mr Murphy and Mr Matthews both took that view. But Mr Palmer points to another of the patent’s goals – improving fluid removal efficiencies – that would be achieved by applying a pressure differential elsewhere than at the input.
[64] Similarly, Mr Palmer contested Western’s construction of claim 19 which contemplates using a pressure differential to enhance the flow of drilling fluid through a first screen “with respect to” a second screen. In Western’s view, this claim requires that the flow of drilling fluid be greater through the first screen as compared to the second screen and, since the flow rate will be greater through the screen at the input side of the shaker, that screen must be the first screen. That is not how Mr Palmer read claim 19. In his view, when the claim refers to “enhancing” the flow of drilling fluid, it simply means improving or increasing it. It does not necessarily mean causing the flow through the first screen to exceed that for the second. It foresees elevating the flow rate through the screen receiving a pressure differential as compared to the screen to which no pressure differential is applied. Mr Murphy and Mr Matthews ultimately agreed that adding a pressure differential to the output screen would increase the flow of drilling fluid through that screen as a percentage of the flow through the input screen.
[65] I conclude that the patent uses the term “first screen” not to identify where the screen is positioned, but to specify the place where a pressure differential is applied. The patent makes no assumption about where the first and second screens are in relation to the input and output sides of the shaker. Where it is necessary to make clear which screen is which, the patent specifically tells the reader. For example, in describing one example of how an embodiment of the invention works, the patent uses the terms “first two screens” and “last two screens”, but makes clear that “first and last corresponds to the direction of flow” from the inlet to the outlet, solely to explain that particular example (para 37). In any case, in that embodiment, a pressure differential is applied to one set of screens, or to the other set, or to both. There is no expressed preference for the pressure differential to be applied at the inlet side as compared to the outlet side. The same is true in respect of other embodiments described in the patent (paras 36, para 45).
[66] Accordingly, I cannot conclude that the term “first screen” invariably means the screen closest to the input side of the shaker. The patent clearly contemplates the application of pressure differentials to either the input side or the output side, or both.
[67] Further, the patent does not specify that the slurry is introduced to the “first screen”. For example, claim 1 merely states that a slurry is introduced to a shaker having a first screen and a second screen and that the slurry passes over the first screen. The slurry would pass over both screens in a two-screen shaker, so one cannot assume that the first screen is at the input side.
(c) “Vapour” and “Hazardous Gases”
[68] The system described in claim 19 involves applying a pressure differential device to a first screen to pull air or vapour through the screen. The patent explains elsewhere that a pressure differential will pull both liquids and vapours through the screen and send them to a degassing chamber. There, the vapours can be collected and flared, vented, or otherwise recovered (para 52). In one embodiment, a fume hood is attached to the shaker to extract vapours, “including potentially hazardous gases, for example, hydrogen sulfide” (para 56). From there, noxious odors or hazardous gases could be treated (para 57).
[69] Mr Murphy explained that vapour generally refers to a mist of airborne liquid particles. However, he stated that the patent is unclear on this point. Mr Palmer agreed that the terminology in the patent “is a bit confusing”, but emphasized that hazardous gases would never be processed through a vacuum pump. Mr Matthews stated that when hazardous gases are present, shakers would simply not be used to process drilling fluid.
[70] On its own, the term “vapour” has a fairly uncomplicated meaning – air or gas containing suspended liquids. Mr. Matthews gave a slightly different definition – “finely divided liquid particles suspended in air”. Mr Palmer and Mr Matthews essentially agreed to that point. The complication arises from the patent’s apparent use of the term vapour to include hazardous, even deadly, gases. The suggestion in the patent that a fume hood or other form of venting could safely treat toxic gases seems implausible. However, the only reference in the patent to hazardous gases relates to the embodiment depicted in Figure 7, and the patent does not claim that embodiment. There is nothing in the patent’s claims about hazardous gases. Other references to vapours in the patent do not mention hazardous gases (paras 48, 52), but address the possibility of flaring or venting vapours.
[71] Accordingly, I do not read the passage in the patent stating that “vapours, including potentially hazardous gases, for example hydrogen sulfide (“H2S”), entrained in the drilling fluid” provides a definition of the word “vapour” for all purposes of the patent. A vapour could include a hazardous gas and in that case the vapour would have to be treated with care. But I do not read the patent as stating that vapour always contains dangerous gases. In that section of the patent, the term “vapour” is used in a very particular context of little assistance to a construction of the patent’s claims.
[72] The patent refers numerous times to the use of a degasser to separate drilling fluid from entrained gases. For example, it states that some of the embodiments “relate to methods and apparatus for removing entrained gases from a slurry” (para 2). However, contrary to Western’s assertion, I do not find those references helpful in interpreting the term “vapour” as it is used in the patent’s claims. A vapour is not an entrained gas. Nor is a gas a vapour.
(d) “Enhancing Flow”
[73] Claim 19 of the patent encompasses a system in which a pressure differential generator pulls air or vapour through the first screen “to enhance the flow of drilling fluid through the first screen with respect to a second screen,” which does not have a pressure differential generator attached. I read this claim as referring to improved flow of fluid through a screen to which a pressure differential device has been attached as compared to one to which no such device is attached. The experts did not differ in any substantial way on this point.
(e) “Controlling Air Flow”
[74] Claim 2 of the patent encompasses a system for applying pressure differential to a screen and controlling the air flow to prevent stalling of the slurry on the screen.
[75] One of the patent’s objects is to address the problem of stalling caused by applying a continuous pressure differential to a shaker’s screens. The patent refers to Hensley, et al., a patent in which a continuous vacuum is applied from under a shaker screen, resulting in solids sticking to the screen (para 13). The patent expresses the need for a shaker with increased pressure differential so long as the means used do not hinder the flow of solids across the screen (para 14).
[76] With respect to the term “controlling air flow,” Mr Murphy suggested that the purpose of this aspect of the invention is to prevent the stalling of slurry on the screen, and that the phrase includes toggling or intermittently interrupting the pressure differential, which are essentially the same thing. Toggling and interrupting the pressure differential are both mentioned specifically in the patent’s disclosure. However, the broader term “controlling air flow” is mentioned in claim 2.
[77] The patent describes some of the potential means for preventing stalling. As Mr Palmer noted, the patent refers to “toggling”, as well as “pulsing or toggling” effectuated by a valve, and “manipulating the valve”. Mr Matthews testified that there is no difference between pulsing, toggling or intermittently interrupting the pressure differential as a means of controlling air flow to prevent stalling. He noted that the patent mentions a broad range of valves, some suited to binary, on-off applications, and others designed for controlling. Mr. Murphy agreed.
[78] The patent contemplates that a pressure differential could be manipulated to provide additional capacity or to improve liquid recovery (para 37). In either case, the airflow must be controlled to prevent stalling.
(f) “Conveying All of the Air or Vapour and Drilling Fluid”
[79] Claim 12 relates to a method of pulling air or vapour and drilling fluid through a screen and conveying all the air, vapour, and drilling fluid to an external chamber where the air or vapour is separated from the fluid. Similarly, claim 20 claims a system in which all the air, vapour, and drilling fluid is sent to a degassing chamber where the air and vapour is separated from the drilling fluid.
[80] Mr Murphy considered the significance of the word “all” in claims 12 and 20. In those claims, “all” of the air or vapour and “all” of the drilling fluid that passes through the screen is sent to a degassing chamber. I