“The present invention relates to apparatus for cleaning the interior bore of well bore tubulars, such as is found in the oil and gas production industries. A distinctive feature of the invention lies in its provision of a means for filtering or screening well fluid while down-hole.”
“The patent is entitled “Apparatus for catching debris in a well bore” and relates to cleaning the fluid and walls of a well bore, such as is found in the oil and gas production industries. This is done using a tool [comprising] a filter through which the well fluid is circulated to remove debris from the fluid. Debris dislodged from the sidewall of the well bore by a wiper is also trapped by the filter. 8. Figure 1 shows the first embodiment described in the patent specification. The tool has an internal bore 3 which communicates with a fluid circulation path, a cylindrical fluid filter screen 6 for trapping debris particles in an annular chamber 9, and a resilient cylindrical cup 5 for wiping debris particles off the sidewall 2 of the well bore and also for diverting fluid flowing in a downward direction relative to the tool into the chamber 9. There is also a ball valve mechanism 10-14 which opens when fluid flows in an upward direction relative to the tool so that the fluid bypasses the filter screen 6. 9. No filtering occurs when the tool is inserted into the well bore, because the fluid is then flowing in an upward direction relative to the tool. The well fluid simply passes through the open ball valve into the chamber 9 and through the bores 8 into the space between the cup 5 and the mandrel 4. When the tool is withdrawn from the well bore, well fluid travels between the cup and the mandrel 4 into the chamber 9 where, because the ball valve is sealed by the pressure of the well fluid, it passes through the filter screen 6. Debris particles are therefore left behind, trapped in the chamber 9. The description says that the well fluid may also be filtered by holding the tool stationary and pumping the fluid down the annulus between the well string and the well wall.”
“The question is always what the person skilled in the art would have understood the patentee to be using the language of the claim to mean. And for this purpose, the language he has chosen is usually of critical importance. The conventions of word meaning and syntax enable us to express our meanings with great accuracy and subtlety and the skilled man will ordinarily assume that the patentee has chosen his language accordingly. As a number of judges have pointed out, the specification is a unilateral document in words of the patentee's own choosing. Furthermore, the words will usually have been chosen upon skilled advice. The specification is not a document inter rusticos for which broad allowances must be made. On the other hand, it must be recognised that the patentee is trying to describe something which, at any rate in his opinion, is new; which has not existed before and of which there may be no generally accepted definition. There will be occasions upon which it will be obvious to the skilled man that the patentee must in some respect have departed from conventional use of language or included in his description of the invention some element which he did not mean to be essential. But one would not expect that to happen very often.”
“I believe Article 69 of the EPC does not legitimately allow courts to construe claims using the prior art either to widen them or narrow them. There is normally no reason to suppose the patentee when he set the limits of his monopoly knew of a particular piece of prior art which is therefore irrelevant in deciding what those limits are. Of course the position is different if the prior art is specifically acknowledged in the patent. The purposive construction would lead to a construction of a claim which did not cover that acknowledged prior art: it can hardly have been the inventor's purpose to cover that which he expressly recognises was old.”
“A down-hole tool for collecting debris particles in a well bore, the tool comprising: a body connectable in a work string having an internal bore running axially there-through which communicates with a circulation path in the work string; a filter in the tool for filtering debris particles from at least some well fluid; and diversion means for diverting said well fluid passing the tool through a flow path in the tool, distinct from the internal bore, which bypasses the filter when fluid flow is in a first direction relative to the tool and through the filter when fluid flow is in the reverse direction relative to the tool.”
“diversion means for diverting said well fluid passing the tool through a flow path in the tool, distinct from the internal bore, which bypasses the filter when fluid flow is in a first direction relative to the tool and through the filter when fluid flow is in the reverse direction relative to the tool”
“If the prior inventor's publication contains a clear description of, or clear instructions to do or make, something that would infringe the patentee's claim is carried out after the grant of the patentee's patent, the patentee's claim will have been shown to lack the necessary novelty, that is to say, it will have been anticipated. The prior inventor, however, and the patentee may have approached the same device from different starting points and may for this reason, or it may be for other reasons, have so described their devices that it cannot be immediately discerned from a reading of the language which they have respectively used that they have discovered in truth the same device; but if carrying out the directions contained in the prior inventor's publication will inevitably result in something being made or done which, if the patentee's patent were valid, would constitute an infringement of the patentee's claim, this circumstance demonstrates that the patentee's claim has in fact been anticipated. If, on the other hand, the prior publication contains a direction which is capable of being carried out in a manner which would infringe the patentee's claim, but would be at least as likely to be carried out in a way which would not do so, the patentee's claim will not have been anticipated, although it may fail on the ground of obviousness. To anticipate the patentee's claim the prior publication must contain clear and unmistakable directions to do what the patentee claims to have invented …A signpost, however clear, upon the road to the patentee's invention will not suffice. The prior inventor must be clearly shown to have planted his flag at the precise destination before the patentees.”
“The fact, however, that there is an overlap between the uses to which two articles can be put does not of itself to my mind make one an anticipation of another. Any article can be used for a purpose for which it was not intended.”
“Referring to figure 2 of D6, the apparatus comprises a tubular mandrel 10, a springloaded positioning sleeve 11 slidably mounted on the mandrel, and an upwardly facing cup-type catcher element 12 slidably mounted on the mandrel above the positioning sleeve. When the apparatus is stationary within the well, the catcher element 12 settles in a position slightly higher than that shown in figure 2, with the portion 25 of the catcher element aligned with the portion 29 of the mandrel. In this position the catcher element forms a seal between the mandrel and the well bore wall, so any sand or debris settling from above will be trapped by the catcher element. When removing the apparatus from the well, the mandrel and positioning sleeve are forced downwards by fluid pressure into the position shown in figure 2. Well fluid now flows downwards (relative to the apparatus) through the passage formed by the catcher element, lower grooves 28 in the mandrel, and slots 36 in the positioning sleeve. The slots in the positioning sleeve are said to be dimensioned to prevent the passage of larger fragments of debris which might prevent the release of the tool, although smaller debris, for example, very fine sand, may pass through the slots.”
“I have looked very carefully at the disclosure in D6 relating to the slots 36 in the sleeve 11. The drawings show the slots as having a similar width to the grooves 28 in the mandrel, but if they did indeed have the same width, the slots would not in use block the passage of anything because any debris larger than the slots would never reach them - it would be blocked by the grooves 28. Mr Burkill relied on this to argue that slots 36 could not be a filter because anything that actually reached them would be small enough to pass through them. However, there is clear teaching in the description that the top portion of the slotted sleeve blocks the passage of larger fragments whilst allowing the passage of fluid, and that is not consistent with Mr Burkill’s interpretation. I must conclude that the skilled person would regard the drawings as merely schematic and would understand that slots 36 must be narrower than the grooves 28 and should be sufficiently narrow to achieve the required degree of blocking. On that basis, I have no doubt in my mind that the slots 36 can properly be described as a filter. It is of no matter that finer particles can pass through the slots, because all filters only block particles above a certain size. The key point is that the slots are capable of blocking some particles.”
“I have carefully considered Mr Burkill’s argument that there is no bypassing because the catcher must be regarded as part of the filter, but I do not accept it. Any filter requires some sort of fluid-channelling arrangement to ensure the fluid goes through the filter and not around it, and that is all the catcher is doing when in the figure 2 position.”
“43 D6 teaches that the slots in the sleeve should be dimensioned so as to prevent the passage of fragments which might prevent the release of the tool string. Mr Miller contended that it would be obvious to place a mesh or a piece of wire across the slots so as to filter finer fragments from the well fluid using the apparatus. He supported this reasoning using two arguments: one relying on a common sense, prima facie, obviousness argument (“it would be an obvious thing to do”), the other relying on Mr McGarian’s evidence. 44 I will consider the common sense argument first. There may be circumstances in which appealing to common sense will be sufficient, but this approach needs to be exercised with care because it is all too easy to jump to the wrong conclusion by not looking at things properly through the eyes of the skilled person, as required by the fourth Windsurfing step. What may seem obvious to a lay person may not be obvious to the skilled person because the latter is aware of potential snags. Conversely, what may seem very clever to the lay person may seem perfectly obvious to the skilled person. 45 D6 teaches that the slots are dimensioned in accordance with the size of the fragments of debris to be trapped. If the notional unimaginative skilled person had reason to trap finer particles, this teaching would lead him or her to use narrower slots. Choosing not to narrow the slots and instead add a separate mesh or extra wire is a diversion from the path suggested by D6. It is not merely a diversion, but a diversion down a more complicated route, since it means adding an extra component and finding a way of doing so that is robust-enough to withstand the rigours of a downhole environment. I am at a loss to see why that is a prima facie obvious step to take. From a “common sense” viewpoint, this is a step that needs a motive, and I cannot see one because, on the face of it, the skilled person can achieve all they need by narrowing the slots. Accordingly, even if the “common sense” approach is a valid one, I do not consider it demonstrates that claim 1 is obvious. 46 I turn now to the evidence of Mr McGarian. He says in his first witness statement that: “The slots 36 in the sleeve 11 of the tool in D6 are merely defined to be dimensioned to prevent the passage of larger fragments of debris. It is, however, obvious to me that the slots 36 could be replaced or augmented by wire screen or (sic) appropriate size, or indeed, a series of wire screens of different permeabilities to enable debris of different sizes to be collected at different points in the trap”
“48 As Mr Burkill rightly said, Mr McGarian fails to give any reasons to back up his assertion that it would be obvious to him to add a wire mesh filter to the slots or trap of the D6 tool. That makes his assertion valueless. Because of this, even ignoring my concerns about the weight I can safely attach to his evidence (and also ignoring the fact that he has failed to say whether it would have been obvious to him in 1998), I do not consider that the evidence provided by Mr McGarian is sufficient to establish that the step of adding a filter is obvious. 49 Hence, claim 1, if novel, is not obvious.”
“A tool as claimed in any one of the preceding claims wherein the filter is elongate and vertically disposed, parallel to the internal bore.”
“Claim 17 is not an intermediate generalisation that falls foul of Palmaz because the provision of the filter is the key part of the inventive concept, and the geometrical advantages of having an elongate vertically disposed cylindrical configuration in an elongate tubular well-bore leap out even to the non-expert and are clearly disclosed by the patent. Those advantages are not dependant on further features such as the trap, so the amended claim 17 does not include any features taken out of context. I consider that the specified features of claim 17 narrow the claimed subject matter down to a subclass. The claim is therefore acceptable so far as added matter is concerned.”
“Claim 23 is not claiming an apparatus which must be suitable for certain purposes. It is claiming a method of doing something, specifically a “method of cleaning a down-hole environment while running a tool on a work string”