T 1988/14 24-10-2019

Reasons for the Decision

1. Amendments

1.1 Claims 1 to 4 of the sole request essential­ly corre­spond to claims 13 to 16 of the first auxiliary request and claims 1-4 of the second auxiliary request under­lying the contested decision, except that the tool is speci­fied as a "down­hole tool" in present claim 1 in­stead of a "logging tool" or merely "tool" as in claim 13 of the former first auxiliary request and claim 1 of the former second auxiliary request.

1.2 In the decision under appeal the opposition division held that the subject-matter of claim 13 of the first auxiliary request underlying the decision did not ex­tend beyond the content of the application as filed (see point 2.4.3 of the Reasons).

1.3 The former respondent had argued that there was no basis in the application as filed for a "downhole" tool comprising a processor performing the claimed opera­tions. Moreover, there was no disclosure of the feature that the tool "connects" to the drilling appara­tus. Hence, claim 13 of the former first auxiliary request extended beyond the application as filed.

No objections had been raised against dependent claims 14 to 16 of that request.

1.4 The board notes that the subject-matter of claim 1 is generally based on claims 8 and 37 as originally filed and on page 28, lines 8 to 10 of the original descrip­tion.

Moreover, the board agrees with the appellant in that the disclosure in the description of the application (see page 12, line 29 - page 13, line 2) that it is only "typically" the case that the tool is "threadably connected" to the drill collar and the drill bit pro­vides the skilled person with the teaching that other types of connections are also possible. There is also no indication whatsoever that the invention as de­scribed would imply one special way of connecting the tool to the drilling apparatus. Hence there is ­a sufficient basis for the somewhat broader for­mu­lation in claim 1 that the tool "connects" to the drilling appara­tus.

The fact that the tool is connected to the drilling apparatus and also that it comprises - according to original claim 8 - the transmitter and receiver anten­nas for determining the resistivity of the earth forma­tion implies that the tool is used in a "downhole" en­vironment. Furthermore, from this claim it also follows that the tool comprises the processor which generates the desired bed boundary indication based on the sig­nals from the receiver antenna and the rotational posi­tion indicator. This is also implied by the disclosure on page 13, lines 3 to 7 of the description of the application. Hence, the original disclosure provides a ­sufficient basis for a "downhole tool" comprising a processor performing the claimed operations.

The subject-matter of claim 1 is therefore di­rect­ly and unambigu­ous­ly derivable from the application as filed.

The description has been brought into conformity with the amended claims and supplemented with an indication of the relevant content of the prior art without ex­tend­ing beyond the content of the application as filed.

Accordingly, the board is satisfied that the amendments comply with the requirements of Article 123(2) EPC.

2. Novelty

2.1 Document E4

2.1.1 Document E4 is an International (PCT) application with a filing date (10 February 2000) before the priority date of the contested patent (13 July 2000) and a pub­lication date (31 August 2000) after that priority date. Hence, the European patent application based on the PCT application E4 belongs to the state of the art according to Article 54(3) EPC for the contracting states under Article 54(4) EPC 1973 as far as the priority of the contested patent is valid, which had not been questioned (Article 89 EPC 1973).

2.1.2 Document E4 discloses (page 7, line 2 - page 8, line 31; page 11, line 9 - page 12, line 28; page 20, lines 3-5; Figures 1, 4, 9) a drill string 14 comprising coil tubing 24 and a bottom hole assembly ("BHA") 26 coupled to the lower end of the coil tubing 24. In particular, the BHA 26 in­cludes an azi­muthal­ly tunable resistivity tool, directional sensors for indicating the rotational angle about the tool axis, and a downhole data signal­ing unit 35. The resis­tivity tool 202 comprises trans­mitter coils 104, 108 and skewed receiver coils 216, 218, 220.

2.1.3 In the contested decision the opposition division held that the subject-matter of claim 1 of the second auxil­iary request underlying the decision was not new over document E4. In particular, the opposition divi­sion did not consider the claimed processing operations to be limited to such embodiments where the processor is located in the downhole tool (see point 2.6.1 of the Reasons). This point of view had also been taken by the former respondent.

2.1.4 The opposition division's objection has been overcome by introducing into present claim 1 the indication that the tool is a "downhole tool" (see point 1.1 above). This implies that claim 1 has to be understood such that the claimed processing operations are in fact performed by a pro­cessor located in the downhole tool.

In document E4 there is no disclosure that the correla­tion of the received electromagnetic wave signals with the orientation signal and the determination of the bed boundary indication are performed by a processor in the downhole tool (see feature (D) of claim 1). Rather, according to the method of document E4 am­pli­tude and phase measure­ments are transmitted to the surface for further pro­cessing to determine formation resistivity, distance and direction to the bed boundary and the resistivity of the adjacent beds (document E4, page 9, lines 9-18; paragraph bridging pages 18-19).

The subject-matter of claim 1 and dependent claims 2 to 4 is therefore new over the European patent appli­ca­tion based on the PCT application E4 (Articles 52(1) and 54(3) EPC and Articles 54(1) and (4) and 89 EPC 1973).

2.2 Document E5

2.2.1 The opposition division held that the subject-matter of claim 1 of the second auxil­iary request underlying the decision was new over document E5 (see point 2.6.2 of the Reasons). The former respondent had argued that the claimed subject-matter lacked novelty over that docu­ment.

2.2.2 According to established case law of the Boards of Appeal subject-matter de­scribed in a document can only be re­garded as having been made available to the public and therefore as comprised in the state of the art, if the information given therein to the skilled person is sufficient to enable him - at the relevant date of the document - to practise the technical teaching of the document, taking into account also common general knowledge at that time in the relevant technical field (see Case Law of the Boards of Appeal of the EPO, 9th edition 2019, section I.C.4.11).

2.2.3 Document E5 discloses (see page 1, left-hand column, para­­graph 1; page 3, left-hand column, paragraph 1; page 4, left-hand column; Figure 4) a proposal for tilt-coil directional induc­tion methods for making deep azimuthal resistivity measurements around a borehole. A simple scale model prototype tool involving one tilted trans­mitter coil and two tilted receiver and corre­spond­ing bucking coils was used to perform model exper­i­ments. Each receiver and its bucking coil were wound in a slant­ed manner on a coil bobbin, which was sliding­ly arranged on a core body allowing adjustment to cancel direct coupling signals. The rele­vant model equa­tions were deduced under the as­sump­tion that the tool body was non-conductive.

The only reference in document E5 to a measurement-while-drilling (MWD) tool is the following statement (page 1, right-hand column, paragraph 2):

"In a horizontal well, it [the tool] will be able to provide a true conductivity of a bed, and also used as a MWD navigation sensor to detect upper or lower beds".

However, document E5 contains no indication at all how the components of the tool, in particular the trans­mitter, receiver and bucking coils are to be integrated into a drill string. On the other hand, there are at­tributes of the prototype of document E5 (slid­ing­ly arranged bobbins) and assumptions used for the deriva­tion of the relevant model equations (non-conductive tool body) which appear incompatible with the harsh MWD operating conditions involving high vibrations, pres­sures and temperatures and the high torques on the drill string. Hence, the above statement does not con­stitute an enabling disclosure of a measurement-while-drilling tool. Features (A) and (E) are therefore not disclosed in document E5. Furthermore, this document does not disclose a processor in a downhole tool performing the claimed operations (feature (B)) and a rotational position indicator (feature (C)), either.

2.2.4 The subject-matter of claim 1 and dependent claims 2 to 4 is therefore new over document E5 (Article 52(1) EPC and Article 54(1) and (2) EPC 1973).

3. Inventive step

3.1 Positions of the opposition division and the former respondent

Inventive step was not discussed in the decision under appeal. However, in the communication annexed to the summons to oral proceedings the opposition division stated its preliminary opinion that the subject-matter of the granted claims did not involve an inventive step over document E6 (see point 9 of the communication).

The former respondent had also argued lack of inventive step over document E11, in particular in view of docu­ment E6.

3.2 Closest state of the art

3.2.1 Document E6 discloses (see page 9, penultimate para­graph - page 10, paragraph 1; page 17, last paragraph - page 18, second paragraph; Figures 1, 7, and 8) a method of and an apparatus for directional induction logging with the aim of measuring the electric conduc­tivity of a formation in a particular direction with respect to the circum­ference of a borehole 7. In particular, the sec­ond embodiment of document E6 concerns the moni­tor­ing of the upper and lower formations 24 and 26 in relation to a horizontal borehole 7. A transmitting coil 1 and a receiving coil 2 are secured to a shaft 10 extending along the hole axis 18 of the borehole 7 such that these coils are inclined so as to face each other. A second trans­mit­ting coil 1' and second receiving coil 2' are also secured to the shaft 10 in a 180-degree symmetry with respect to the first transmit­ting and receiving coils 1 and 2. A weight 27 is secured to the shaft 10 and rotatably sustained by bearings 16 sup­port­ing the shaft such that one of the pairs of the transmitting and receiving coils is directed in the gravitational direction at all times. This apparatus permits measurement of the electric conductivity on the gravity side of the borehole and the opposite side thereof.

In relation to the second embodiment document E6 con­tains the following statement (page 19, penultimate para­graph):

"Further, when the apparatus is applied to a sensor for MWD (Measurement While Drilling), it consti­tutes a navigation tool for drilling a borehole without getting out of the intended formation."

A corresponding statement is also contained in the general description of the invention (see document E6, page 1):

"Among the fields of utility, to which the invention is applicable, are as follows.

[...]

(2) Measurement sensors in the MWD (Measurement While Drilling) techniques for making measurements during drilling a borehole:

When carried out as a resistivity sensor in the MWD, the invention permits monitoring of upper and lower formations during horizontal drilling or the like."

However, the second embodiment of document E6 clearly relates to a wireline logging device which is designed for being lowered into an existing borehole for collec­ting data and removed afterwards. Furthermore, document E6 does not contain any indications on how the tool is to be adap­ted for being used as a measurement-while-drilling tool, in par­ticular how it is to be incor­po­rat­ed into a drill string. Just like in the case of document E5 (see point 2.2.3 above) some of the (im­plied) at­tributes of the tool according to the second embodiment of E6 (non-con­ductive housing; weight 27 for controlling the orienta­tion of the coils) do not appear to be compatible with the harsh MWD operating environ­ment­ and the drill string's rotation under high torque conditions. Hence, document E6 does not disclose a measure­ment-while-drilling tool in an enabling manner. Con­sequently, this document is not considered the clos­est state of the art as it is not conceived for the same purpose as the claimed inven­tion, namely for pro­viding a geo-steering method.

3.2.2 On the other hand, document E11 discloses - as detailed below - subject-matter that is conceived for the same purpose as the claimed inven­tion and has the most relevant technical features in common with it. There­fore, the board agrees with the former respondent in regarding document E11 as the closest state of the art.

3.3 Distinguishing features

3.3.1 Document E11 discloses (see column 6, line 44 - column 7, line 11; Figures 1 and 2) a logging tool 10 sus­pend­ed in an earth borehole 12 on a string of drill pipe 14 from the earth's surface, such drill string including one or more drill collars 11. A transmitter section with transmitters 16, 18 and 20 is spaced along the length of the logging tool 10 from a receiver section 22 which includes a pair of receivers R1 and R2. The transmitters 16, 18 and 20 and the receivers R1 and R2 are covered with a non-conductive material. The body of tool 10 is made of steel in order to prevent the tool 10 from becoming a weak link in the drill string 14. Typically, one or more drill collars 24 with drill bits are connected to a lower end of the logging tool 10. The logging tool 10 also has the requisite electronic circuitry for processing the signals received by the receiver section 22, thereby converting the received signals into a log or another indication of formation resistivity.

3.3.2 Using the wording of claim 1 document E11 discloses therefore a geosteering method that comprises:

(A) transmitting an electromagnetic wave from a trans­mitter antenna (one of transmitters 16, 18 and 20) into a formation, wherein the transmitter antenna is mounted on a downhole tool (logging tool 10) disposed in a plane oriented at a first angle with respect to the longitudinal axis of the tool, wherein the tool (logging tool 10) connects to a drilling apparatus (drill pipe 14);

(B)' receiving an electromagnetic wave response from the formation with a receiver antenna (one of receivers R1 and R2) spaced apart from said transmitter antenna along the tool axis;

(D)' using a processor (electronic circuitry) in the downhole tool to convert the received signals into an indication of formation resistivity.

The subject-matter of claim 1 differs from the method of document D11 in

(B)'' the receiver antenna being mounted on the tool disposed in a plane oriented at a second angle with respect to the tool axis, wherein the first and second angles have different magnitudes;

(C) generating an orientation signal representative of the orientation of the tool with respect to a refer­ence direction using a rotational position indica­tor attached to said tool;

(D)'' using the processor to corre­late the received electromagnetic wave response with the orientation signal from the rotational position indicator and to determine a bed boundary indication based on the received electromagnetic wave; and

(E) controlling a direction of the drilling apparatus based on the bed boundary indication."

3.4 Objective technical problem

In accordance with the indications in the patent speci­fication (see paragraph [0014]) it is the objective technical problem of the invention to provide an im­proved method for steering a downhole apparatus during a directional drilling operation in order to maintain the borehole within a desired earth formation.

3.5 Obviousness

3.5.1 Document E4 belongs to the state of the art according to Article 54(3) EPC and is therefore not to be con­sidered in deciding whether there has been an inventive step (Article 56 EPC 1973).

3.5.2 Neither document E5 nor document E6 discloses a mea­sure­­ment-while-drilling tool and a corresponding method in an enabling manner (see points 2.2.3 and 3.2.1 above). Hence, these docu­ments do not provide the skilled person with a solution to the posed technical problem of im­proving the stee­ring of a downhole appa­ratus during a direc­tio­nal dril­ling operation in order to maintain the bore­hole within a desired earth formation.

Moreover, neither the oppo­si­tion division nor the for­mer respondent had advanced any arguments that the ma­jor adaptations necessary for transforming the wireline logging methods disclosed in documents E5 and E6 into measurement-while-drilling methods were obvious for the skilled person in view of its common general knowledge. The board does not see any reasons for believing that this is the case, either.

3.5.3 Therefore, the subject-matter of claim 1 and dependent claims 2 to 4 involves an inventive step (Article 52(1) EPC and Article 56 EPC 1973).

4. Conclusion

For the above reasons the board is of the opinion that the patent - in the version according to the appel­lant's sole request - and the invention to which it relates meet the requirements of the EPC. Hence, the patent is to be maintained as amended in that version (Article 101(3)(a) EPC and Article 111(1) EPC 1973).