(19)
(11)EP 2 732 133 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
26.06.2019 Bulletin 2019/26

(21)Application number: 12830986.1

(22)Date of filing:  31.08.2012
(51)International Patent Classification (IPC): 
G01V 1/46(2006.01)
(86)International application number:
PCT/US2012/053269
(87)International publication number:
WO 2013/039712 (21.03.2013 Gazette  2013/12)

(54)

ACOUSTIC LOGGING WHILE DRILLING TOOL WITH ACTIVE CONTROL OF SOURCE ORIENTATION

AKUSTISCHE BOHRLOCHMESSUNG WÄHREND DES BOHRENS MIT AKTIVER STEUERUNG DER QUELLENORIENTIERUNG

OUTIL DE DIAGRAPHIE ACOUSTIQUE EN COURS DE FORAGE ÉQUIPÉ D'UNE COMMANDE ACTIVE DE L'ORIENTATION DE LA SOURCE


(84)Designated Contracting States:
AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

(30)Priority: 14.09.2011 US 201113232419

(43)Date of publication of application:
21.05.2014 Bulletin 2014/21

(73)Proprietors:
  • Services Pétroliers Schlumberger
    75007 Paris (FR)
    Designated Contracting States:
    FR 
  • Schlumberger Holdings Limited
    Road Town, Tortola 1110 (VG)
    Designated Contracting States:
    GB NL 
  • Schlumberger Technology B.V.
    2514 JG The Hague (NL)
    Designated Contracting States:
    AL AT BG CH CY CZ DE DK GR HR HU IE IT LI LT NO PL RO SI SK TR 
  • Prad Research And Development Limited
    Tortola 1110 (VG)
    Designated Contracting States:
    BE EE ES FI IS LU LV MC MK MT PT RS SE SM 

(72)Inventor:
  • PABON, Jahir
    Newton, Massachusetts 02460 (US)

(74)Representative: Schlumberger Intellectual Property Department 
Parkstraat 83
2514 JG Den Haag
2514 JG Den Haag (NL)


(56)References cited: : 
EP-A2- 0 837 217
WO-A1-99/35490
US-A1- 2007 268 782
US-A1- 2009 205 899
WO-A1-98/48140
US-A1- 2004 158 997
US-A1- 2008 170 466
US-B1- 6 366 531
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    Field



    [0001] The subject disclosure generally relates to formation evaluation. More particularly, the subject disclosure relates to sonic measurements while drilling or wireline sonic logging.

    Background



    [0002] A downhole acoustic logging tool generally contains one or a plurality of acoustic sources and an array of acoustic receivers. The one or a plurality of acoustic sources can be of a multi-pole nature (generally monopole, dipole and quadrupole). Both US 6 366 531 and US 2009/205899 disclose an acoustic borehole logging while drilling (LWD) tool. with a multi-pole capable acoustic source. A multi-pole source is made up of two more elements placed at the same axial location on the tool and generally equally spaced around the circumference. At least two source elements are needed for an acoustic dipole field and at least four are needed for a quadrupole field. The array of acoustic receivers is decided so as to capture the multi-pole nature of the propagating acoustic field. In general 4-12 acoustic receivers are placed along the tool axis; with each receiver comprising one or more acoustic sensing elements distributed along the tool circumference (at least two are needed to capture dipole and at least four are needed to capture quadrupole).

    [0003] A logging event consists of firing the one or more individual elements of an acoustic source to generate a desired acoustic field in the borehole (generally monopole, dipole or quadrupole); and recording the acoustic (pressure) signal at each of the receivers' sensing elements, as it propagates along the wellbore. The recorded traces are processed, first to extract the different acoustic field components (monopole, dipole or quadrupole). Each of those field components is further processed to extract acoustic properties of the formation being traversed by the wellbore.

    [0004] It is widely known that in acoustic logging while drilling, because of the generally strong acoustic noise generated by the drilling operation, there is a need to stack (add up) the traces recorded by several individual logging events (typically 16-64 traces) in order to enhance the signal to noise ratio. The basic idea is that the signal being excited by repeated firings of the acoustic source will be nicely correlated and therefore will add up. In contrast, the signal from a drilling noise will be largely uncorrelated and therefore will tend to cancel out. The stacking then improves the quality of the subsequent processing.

    [0005] Stacking works well when the tool is not rotating between source firings or the formation being traversed by the wellbore exhibits acoustic isotropic behavior around the wellbore axis i.e. if the acoustic field generated in the wellbore by the firing of a multi-pole source is the same independent of the orientation of the source as the tool rotates. However, more often than not, this is not the case, particularly when drilling highly deviated wells. In this situation, the stacking will tend to average out important information about the anisotropic properties of the formation.

    [0006] It is possible to have sensors in the tool that measure and record the instantaneous tool face angle (i.e. the instantaneous orientation as the tool rotates) that goes along with each logging event. The stacking can then be done on logging events that correspond to similar (or equivalent) instantaneous tool orientations. However, the stacked events will generally extend over an appreciable number of tool revolutions, and the tool might have moved appreciably (because of the drilling operation) during that time. The stacking will tend to average out variations in the rock properties along the wellbore.

    [0007] Therefore, a better solution is desired to improve the quality of acoustic logging while drilling when the formation exhibits acoustic anisotropy.

    Summary



    [0008] This summary is provided to introduce a selection of concepts that are further described below in the detailed description. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used as an aid in limiting the scope of the claimed subject matter.

    [0009] An acoustic borehole logging while drilling tool according to claim 1 is disclosed.

    [0010] A method according to claim 9 of acoustic borehole logging with a logging while drilling tool is disclosed.

    [0011] Further features and advantages of the subject disclosure will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings.

    Brief Description of the Drawings



    [0012] The subject disclosure is further described in the detailed description which follows, in reference to the noted plurality of drawings by way of non-limiting examples of embodiments of the subject disclosure, in which like reference numerals represent similar parts throughout the several views of the drawings, and wherein:

    FIG. 1 depicts a wellsite system in which the subject disclosure may be employed;

    FIG. 2 depicts a sonic logging-while-drilling tool;

    FIG. 3 depicts a logging while drilling acoustic tool with active source orientation control;

    FIG. 4 depict an alternate embodiment of a logging while drilling acoustic tool with active source orientation control;

    FIG. 5 depicts a cross section of a logging while drilling tool through the acoustic source;

    FIG. 6 depicts a flow diagram of the independent control of each source element;

    FIG. 7 depicts a flow diagram of the independent recording of each sensing element; and

    FIG. 8 depicts an alternate embodiment of the subject disclosure.


    Detailed Description



    [0013] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the subject disclosure only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the subject disclosure. In this regard, no attempt is made to show structural details in more detail than is necessary for the fundamental understanding of the subject disclosure, the description taken with the drawings making apparent to those skilled in the art how the several forms of the subject disclosure may be embodied in practice. Furthermore, like reference numbers and designations in the various drawings indicate like elements.

    [0014] Figure. 1 illustrates a wellsite system in which the subject disclosure can be employed. The wellsite can be onshore or offshore. In this exemplary system, a borehole 11 is formed in subsurface formations by rotary drilling in a manner that is well known. Embodiments of the subject disclosure can also use directional drilling, as will be described hereinafter.

    [0015] A drill string 12 is suspended within the borehole 11 and has a bottom hole assembly 100 which includes a drill bit 105 at its lower end. The surface system includes platform and derrick assembly 10 positioned over the borehole 11, the assembly 10 including a rotary table 16, kelly 17, hook 18 and rotary swivel 19. The drill string 12 is rotated by the rotary table 16, energized by means not shown, which engages the kelly 17 at the upper end of the drill string. The drill string 12 is suspended from a hook 18, attached to a traveling block (also not shown), through the kelly 17 and a rotary swivel 19 which permits rotation of the drill string relative to the hook. As is well known, a top drive system could alternatively be used.

    [0016] In the example of this embodiment, the surface system further includes drilling fluid or mud 26 stored in a pit 27 formed at the well site. A pump 29 delivers the drilling fluid 26 to the interior of the drill string 12 via a port in the swivel 19, causing the drilling fluid to flow downwardly through the drill string 12 as indicated by the directional arrow 8. The drilling fluid exits the drill string 12 via ports in the drill bit 105, and then circulates upwardly through the annulus region between the outside of the drill string and the wall of the borehole, as indicated by the directional arrows 9. In this well known manner, the drilling fluid lubricates the drill bit 105 and carries formation cuttings up to the surface as it is returned to the pit 27 for recirculation.

    [0017] The bottom hole assembly 100 of the illustrated embodiment has a logging-while-drilling (LWD) module 120, a measuring-while-drilling (MWD) module 130, a roto-steerable system and motor, and drill bit 105.

    [0018] The LWD module 120 is housed in a special type of drill collar, as is known in the art, and can contain one or a plurality of known types of logging tools. It will also be understood that more than one LWD and/or MWD module can be employed, e.g. as represented at 120A. (References, throughout, to a module at the position of 120 can alternatively mean a module at the position of 120A as well.) The LWD module includes capabilities for measuring, processing, and storing information, as well as for communicating with the surface equipment. In the present embodiment, the LWD module includes a sonic measuring device.

    [0019] The MWD module 130 is also housed in a special type of drill collar, as is known in the art, and can contain one or more devices for measuring characteristics of the drill string and drill bit. The MWD tool further includes an apparatus (not shown) for generating electrical power to the downhole system. This may typically include a mud turbine generator powered by the flow of the drilling fluid, it being understood that other power and/or battery systems may be employed. In the present embodiment, the MWD module includes one or more of the following types of measuring devices: a weight-on-bit measuring device, a torque measuring device, a vibration measuring device, a shock measuring device, a stick slip measuring device, a direction measuring device, and an inclination measuring device.

    [0020] Figure 2 illustrates a sonic logging-while-drilling tool which can be the LWD tool 120, or can be a part of an LWD tool suite 120A of the type described in U.S. Patent No. 6,308,137. FIG. 2 illustrates selected components of a sonic logging while drilling tool 120 schematically according to embodiments of the subject disclosure. A pipe portion (203) defines a mud channel (205) and distributed on the pipe portion (203) are one or a plurality of transmitters (201) capable of at least monopole, dipole and quadrupole firings. A receiver (207) or a plurality of receivers (207) and receiver electronics (211) are distributed on the pipe portion (203). A processing system controls the firing of the transmitters (201) and the receiver electronics (211). The processing facility can be located in one or more locations at the wellsite. According to some embodiments, the processing and interpretation of the data from the tools is performed at one or more locations remote from the wellsite. The processing facility may include one or more central processing units, storage system, communications and input/output modules, a user display and a user input system.

    [0021] According to some embodiments an acoustic LWD tool is disclosed. The tool comprises at least one acoustic source with multiple source elements distributed around a drill collar, each source element independently controlled so that the acoustic source as a whole can generate acoustic signals of multi-pole nature along different orientations with respect to the tool body. The tool also has one or more sensors that are used to determine the instantaneous tool face angle or collar orientation as the tool rotates. According to some embodiments, the one or more sensors may be a combination of an accelerometer, a gyro and/or a magnetometer.

    [0022] The tool also includes an array of acoustic receivers. Each receiver is made of multiple acoustic sensing elements distributed around the collar wall. Each sensing element in the receiver is independently recorded, so that by appropriate weighting of the recorded signals, the different multi-pole components of the acoustic signal propagating along the well along any desired orientation may be extracted.

    [0023] The tool also includes source firing electronics that uses the measured instantaneous tool face (collar orientation) to control the firing of the individual source elements so that the direction of the multi-pole acoustic signal generated by the acoustic source as a whole has one or more predetermined orientations. Firing at two orthogonal orientations (90° angle between orientations for dipole, 45° for quadrupole) may be used to facilitate processing that leads to extraction of anisotropic rock properties. See United States Patent No.: 7,623,412, entitled "Anisotropy measurement while drilling".

    [0024] According to some embodiments, as the tool rotates, the one or two directions of the multi-pole acoustic signal generated by the source are to be kept geo-stationary to facilitate the stacking of the multiple individual logging events associated with each of the source directions. This is to enhance signal to noise ratio as explained above, without averaging out the anisotropic properties of the formation.

    [0025] According to some embodiments, to allow appropriate control of the direction of the multi-pole acoustic field, a plurality of source elements is necessary. In non-limiting examples, for a dipole the number of source elements is at least four, in other examples, the number of source elements is at least eight for a dipole or a quadrupole, and in other non-limiting examples, the number of source elements is at least 16, for a source that, as a whole can excite dipole and quadrupole acoustic fields at arbitrary orientations around the tool axis.

    [0026] FIG. 3 depicts an embodiment of a logging while drilling (LWD) acoustic tool (309) with active source orientation control. FIG. 3 illustrates selected components of the LWD tool (309) schematically according to one embodiment. The drill string (12) of FIG. 1 includes a plurality of drill collars. The LWD tool (309) may comprise the same general shape as one or more of the drill collars, including a pipe portion (313). The pipe portion (313) defines a mud channel (315). The LWD tool (309) has at least one acoustic source (305) with multiple source elements distributed around the collar circumference, each source element independently controlled so that the acoustic source (305) as a whole can generate signals of multi-pole nature, including monopole, dipole and quadrupole, along different orientations with respect to the tool body. The LWD tool (309) also has one or a plurality of sensors (301) that are used to determine the instantaneous tool face angle i.e. the collar orientation as the collar rotates. The plurality of sensors (301) may comprise a combination of an accelerometer, gyro and/or magnetometer. The LWD tool (309) further comprises an array of acoustic receivers or acoustic sensors (307). Each acoustic receiver (307) is made up of multiple acoustic sensing elements distributed around the collar wall (311). Each acoustic sensing element in the acoustic receiver is independently recorded, so that by appropriate weighting of the recorded signals, the different multi-pole components of the acoustic signal propagating along the well along any desired orientation can be extracted.

    [0027] The LWD tool (309) may also comprise source firing electronics (303) that uses the measured instantaneous tool face (collar orientation) to control the firing of the individual source elements so that the direction of the multi-pole acoustic signal generated by the acoustic source (305) as a whole has one or more predetermined orientations.

    [0028] FIG. 4 depicts an alternate embodiment of a logging while drilling (LWD) acoustic tool (409) with active source orientation control. The acoustic sensing elements are placed in axial grooves (411) disposed in an outer surface of the LWD tool. Other methods of disposing the acoustic sensing elements on the LWD tool are contemplated, for example, each acoustic sensing element may be a blank hole machined on the LWD tool collar. The LWD tool (409) has source electronics (403), collar orientation sensors (405), acoustic sensors (407) and one or more multipole acoustic source(s) (401) similar to the LWD tool (309) of FIG. 3.

    [0029] Figure 5 shows a cross section of a multipole acoustic source (515), which in this non-limiting example is made up of 16 individually controlled source elements (501) which form the multipole acoustic source (515) transmitter. The individually controlled source elements (501) are embedded in grooves disposed in an insulating material (507) in a drill collar (505). A protective shield (511) surrounds and protects the individually controlled source elements (501). In one non-limiting example this protective shield (511) is steel. A mud channel (503) of the drill collar (505) is also present. The firing of each source element (501) is independently controlled. To allow appropriate control of the direction of the multi-pole acoustic field, the number of source elements (501) is at least eight. In other non-limiting embodiments the number of source elements (501) is at least four for dipole and eight for dipole and quadrupole. This is for an acoustic source which as a whole can excite dipole and quadrupole acoustic fields at arbitrary orientations around the tool axis.

    [0030] Figure 6 is a simple flow diagram of some embodiments of the subject disclosure. Figure 6 depicts a process to follow when firing the source. The modulated amplitudes of the individual source elements are to be based on the desired multi-pole nature of the acoustic field to be excited, the desired orientation of that field in geostationary coordinates, and the relative orientation of each individual element with respect to the desired multi-pole source orientation. A typical expression for the amplitude of each source element is as follows:


    where A is a parameter representing the strength of the source as a whole; n indicates the type of acoustic field to be generated (0 for monopole, 1 for dipole, 2 for quadrupole); θt is the instantaneous tool face orientation measured by the one or more tool face orientation sensors in the tool; θi is the orientation of the individual source element with respect to the reference tool face; θs is the desired orientation of the multi-pole acoustic field to be generated by the source as whole; and Ai is the strength of the signal applied to the ith source element. Both θt and θs are measured with respect to a geostationary coordinate system (typically θs = 0 and indicates "up", 90° → east, 180° → down, 270° → west).

    [0031] By keeping a constant geostationary direction of the multi-pole acoustic field excited by the source in between consecutive individual logging events (even as the tool rotates), those events can be stacked to enhance signal to noise without averaging out the anisotropic properties of the rock.

    [0032] Referring to FIG. 6 the process for firing the acoustic source comprises a first step (601) of sensing instantaneously a tool face angle. The second step (603) is modulating the amplitude of firing signals for each active element in the source array according to the instantaneous tool orientation and the orientation of individual sensors using Equation 1 above. The third step (605) is the firing of a plurality of signals (605) in each of the individual source elements (606).

    [0033] Fig. 7 is a flow diagram illustrating the capturing of the traces in all acoustic receivers associated with a logging event. The process of extracting the different multi-pole components of the field and the subsequent process of extracting acoustic rock properties from the recorded data, including anisotropic properties has been described in U.S. Patent No.: 4,594,691, entitled "Sonic Well Logging", and U.S. Patent No.: 7,623,412, entitled "Anisotropy measurement while drilling".

    [0034] Referring to FIG. 7 the first step in the flow diagram is the instantaneous sensing of a tool face angle (701). In non-limiting examples, this step (701) is the same step as the step (601), or in other examples, the step (601) and the step (701) are carried out simultaneously. The next step (703) is the step of storing the amplitude of sensing signals from each sensing element (705) in each receiver as well as the instantaneous tool face angle so that the different propagating borehole modes can be computed or extracted.

    [0035] A further application of the subject disclosure which will benefit from having active control of the orientation of the acoustic source is Borehole Acoustic Reflection (and/or refraction) Surveys while drilling (LWD BARS). The BARS tool allows reservoir features such as reflectors and fractures to be imaged. Additional information regarding sonic imaging in general and the BARS tool in general may be found in the following documents. Yamamoto et al., entitled "Borehole Acoustic Reflection Survey Experiments in Horizontal Wells for Accurate Well Positioning", SPE/Petroleum Society of CIM 65538 and United States Patent No.: 6,956,790 to Jakob Haldorsen, entitled "Borehole Sonic Data Processing Method". FIG. 8 depicts active control of the acoustic source orientation which may be used to clearly detect a location of a geological marker, in a non-limiting example, a layer boundary. As illustrated in FIG. 8 a wellbore (809) is depicted with a logging while drilling tool (800). Connected to the lower end of the drill string is a drill bit (813). An acoustic source (803), in one non-limiting example, a dipole source is fired and one or a plurality of acoustic receivers (807) are used to record any signal reflected (811) from a geological feature, in one non-limiting example a layer boundary (805). The dipole source in one non-limiting example comprises at least four independently controlled source elements and in other examples comprises eight or more independently controlled source elements. The orientation of the acoustic source (803) can initially be rotated, either as the tool rotates (815) or with the active control of orientation described above. Processing is performed to get an initial indication for the presence of a reflector, and a rough estimate of the orientation. The processing has previously been described. See Yamamoto et al., entitled "Borehole Acoustic Reflection Survey Experiments in Horizontal Wells for Accurate Well Positioning", SPE/Petroleum Society of CIM 65538 and United States Patent No.: 6,956,790 to Jakob Haldorsen, entitled "Borehole Sonic Data Processing Method". After processing, the orientation of the acoustic dipole source can be controlled to point in the direction where the reflector is expected or as the tool rotates independently of the tool rotation, as depicted in FIG. 8, and multiple firings may be performed to more clearly define the location (orientation and distance) of the reflector. The control of the acoustic dipole source has been described above.


    Claims

    1. An acoustic borehole logging while drilling tool comprising:

    at least one acoustic source (201, 305, 401, 515) comprising a plurality of source elements wherein each of the plurality of source elements (501) is independently controlled so that the at least one acoustic source can generate a multi-pole acoustic signal along different orientations with respect to the tool;

    at least one acoustic receiver (207, 307, 407) comprising a plurality of acoustic sensing elements (705);

    characterized by a plurality of sensors (301) configured for determining an instantaneous tool face angle while the tool is rotating in the borehole;

    a source firing control (303) configured to use the instantaneous tool face angle to control a firing of the plurality of source elements while the tool is rotating in the borehole, the control being such that a direction of the multi-pole acoustic signal generated by the at least one acoustic source is geostationary and has one or more predetermined geostationary directions; and

    receiver recording electronics (211) configured to record independently sensing signals from each of the plurality of acoustic sensing elements (705) together with the instantaneous tool face angle.


     
    2. The acoustic borehole logging while drilling tool of claim 1, wherein the plurality of source elements are distributed around a circumference of a tool collar.
     
    3. The acoustic borehole logging while drilling tool of claim 1 or claim 2, wherein the multi-pole acoustic signal is a monopole, dipole, or quadrupole signal.
     
    4. The acoustic borehole logging while drilling tool of any one of claims 1 to 3, wherein the plurality of sensors are a combination of accelerometer, gyro and magnetometer.
     
    5. The acoustic borehole logging while drilling tool of any one of claims 1 to 4 wherein the source firing control (303) is configured such that the one or more predetermined geostationary directions comprise two predetermined geostationary directions at 45° to each other and wherein the acoustic source is a quadrupole source.
     
    6. The acoustic borehole logging while drilling tool of any one of claims 1 to 4 wherein the source firing control (303) is configured such that the one or more predetermined geostationary directions comprises two predetermined geostationary directions at 90° to each other and wherein the acoustic source is a dipole source.
     
    7. The acoustic borehole logging while drilling tool of any one of claim 1 to 6, wherein the plurality of sensing elements are distributed around a collar wall of a collar housing of the tool.
     
    8. The acoustic borehole logging while drilling tool of any one of claims 1 to 7, wherein the number of source elements for each of the at least one acoustic sources is four or multiples of four and the acoustic signal is dipole.
     
    9. A method of acoustic borehole logging with a logging while drilling tool comprising at least one acoustic source comprising a plurality of source elements (501) at least one acoustic receiver (207, 307, 407) comprising a plurality of acoustic sensing elements, and characterized by a plurality of sensors (301, 405) for determining an instantaneous tool face angle while the tool is rotating in the borehole, the method comprising:

    sensing (601, 701) an instantaneous tool face angle while the tool is rotating in the borehole;

    modulating (603) an amplitude of a firing signal for each source element in a plurality of source elements according to the instantaneous tool face angle so that a direction of the multi-pole acoustic signal generated by the at least one acoustic source is controlled to be geostationary and has one or more predetermined geostationary directions;

    firing (605) the acoustic signal; and

    recording (703) independently sensing signals from each of the plurality of acoustic sensing elements (705) together with the instantaneous tool face angle.


     
    10. The method of claim 9 wherein the one or more predetermined geostationary directions comprise two predetermined geostationary directions at 45° to each other and wherein the acoustic source is a quadrupole source.
     
    11. The method of claim 9 wherein the one or more predetermined geostationary directions comprise two predetermined geostationary directions at 90° to each other and wherein the at least one acoustic source is a dipole source.
     
    12. A method according to any one of claims 9 to 11 further comprising processing the recorded sensing signals to extract logging events associated with the predetermined source directions.
     
    13. A method according to any one of claims 9 to 12 further comprising making multiple firings of the at least one acoustic source and stacking a plurality of logging events associated with one or more predetermined directions.
     
    14. A method according to any one of claims 9 to 13 wherein the at least one receiver is used to record a return acoustic signal from a geological feature and the orientation of the at least one acoustic source is controlled to point in a direction where the return acoustic signal is expected.
     


    Ansprüche

    1. Akustisches Bohrloch-Logging-While-Drilling-Gerät mit:

    wenigstens einer Schallquelle (201, 305, 401, 515), mit mehreren Quellenelementen, wobei die mehreren Quellenelemente (501) jeweils unabhängig voneinander gesteuert werden, so dass die wenigstens eine Schallquelle ein akustisches Multipolsignal entlang verschiedener Orientierungen in Bezug auf das Gerät generieren kann;

    wenigstens einem Schallempfänger (207, 307, 407) mit mehreren Schallerfassungselementen (705);

    gekennzeichnet durch

    mehrere Sensoren (301), die dazu ausgelegt sind, einen momentanen Toolface-Winkel zu bestimmen, während das Gerät sich im Bohrloch dreht;

    eine Quellenabfeuerungssteuerung (303), die dazu ausgelegt ist, den momentanen Toolface-Winkel zum Steuern eines Abfeuerns der mehreren Quellenelemente zu verwenden, während das Gerät sich im Bohrloch dreht, wobei die Steuerung solcherart ist, dass eine Richtung des von der wenigstens einen Schallquelle generierten akustischen Multipolsignals geostationär ist und ein oder mehrere vorbestimmte geostationäre Richtungen aufweist; und

    Empfängeraufzeichnungselektronik (211), die dazu ausgelegt ist, unabhängig voneinander Erfassungssignale aus jedem der mehreren Schallerfassungselemente (705) zusammen mit dem momentanen Toolface-Winkel aufzuzeichnen.


     
    2. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach Anspruch 1, wobei die mehreren Quellenelemente um einen Umfang einer Geräte-Schwerstange verteilt sind.
     
    3. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach Anspruch 1 oder Anspruch 2, wobei das akustische Multipolsignal ein Monopol-, Dipol- oder Quadrupolsignal ist.
     
    4. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach einem der Ansprüche 1 bis 3, wobei die mehreren Sensoren eine Kombination aus Beschleunigungssensor, Kreiselkompass und Magnetometer sind.
     
    5. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach einem der Ansprüche 1 bis 4, wobei die Quellenabfeuerungssteuerung (303) so ausgelegt ist, dass die eine oder die mehreren vorbestimmten geostationären Richtungen zwei vorbestimmte geostationäre Richtungen in einem Winkel von 45° zueinander umfassen, und wobei die Schallquelle eine Quadrupolquelle ist.
     
    6. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach einem der Ansprüche 1 bis 4, wobei die Quellenabfeuerungssteuerung (303) so ausgelegt ist, dass die eine oder die mehreren vorbestimmten geostationären Richtungen zwei vorbestimmte geostationäre Richtungen in einem Winkel von 90° zueinander umfasst, und wobei die Schallquelle eine Dipolquelle ist.
     
    7. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach einem der Ansprüche 1 bis 6, wobei die mehreren Erfassungselemente um eine Schwerstangenwandung eines Schwerstangengehäuses des Gerätes verteilt sind.
     
    8. Akustisches Bohrloch-Logging-While-Drilling-Gerät nach einem der Ansprüche 1 bis 7, wobei die Anzahl von Quellenelementen für jede der wenigstens einen Schallquelle vier oder ein Vielfaches von vier beträgt, und das akustische Signal ein Dipolsignal ist.
     
    9. Verfahren zum akustischen Bohrloch-Logging mit einem Logging-While-Drilling-Gerät mit wenigstens einer Schallquelle mit mehreren Quellenelementen (501), wenigstens einem Schallempfänger (207, 307, 407) mit mehreren Schallerfassungselementen, und
    gekennzeichnet durch
    mehrere Sensoren (301, 405) zum Bestimmen eines momentanen Toolface-Winkels, während das Gerät sich im Bohrloch dreht, wobei das Verfahren umfasst:

    Erfassen (601, 701) eines momentanen Toolface-Winkels, während das Gerät sich im Bohrloch dreht;

    Modulieren (603) einer Amplitude eines Abfeuersignals für jedes Quellenelement in mehreren Quellenelementen gemäß des momentanen Toolface-Winkels, so dass eine Richtung des von der wenigstens einen Schallquelle generierten akustischen Multipolsignals dahingehend gesteuert wird, geostationär zu sein, und ein oder mehrere vorbestimmte geostationäre Richtungen aufweist;

    Abfeuern (605) des akustischen Signals; und

    unabhängig voneinander Aufzeichnen (703) von Erfassungssignalen aus jedem der mehreren Schallerfassungselemente (705) zusammen mit dem momentanen Toolface-Winkel.


     
    10. Verfahren nach Anspruch 9, wobei die eine oder die mehreren vorbestimmten geostationären Richtungen zwei vorbestimmte geostationäre Richtungen in einem Winkel von 45° zueinander umfassen, und wobei die Schallquelle eine Quadrupolquelle ist.
     
    11. Verfahren nach Anspruch 9, wobei die eine oder die mehreren vorbestimmten geostationären Richtungen zwei vorbestimmte geostationäre Richtungen in einem Winkel von 90° zueinander umfassen, und wobei die wenigstens eine Schallquelle eine Dipolquelle ist.
     
    12. Verfahren gemäß einem der Ansprüche 9 bis 11, das ferner ein Verarbeiten der aufgezeichneten Erfassungssignale umfasst, um den vorbestimmten Quellenrichtungen zugeordnete Logging-Ereignisse zu extrahieren.
     
    13. Verfahren gemäß einem der Ansprüche 9 bis 12, das ferner umfasst, mehrere Abfeuerungen der wenigstens einen Schallquelle vorzunehmen, und mehrere, einer oder mehreren vorbestimmten Richtungen zugeordnete Logging-Ereignisse zu stacken.
     
    14. Verfahren nach einem der Ansprüche 9 bis 13, wobei der wenigstens eine Empfänger dazu verwendet wird, ein Schallrücksignal aus einer geologischen Gegebenheit aufzuzeichnen, und die Orientierung der wenigstens einen Schallquelle dahingehend gesteuert wird, in eine Richtung zu weisen, in der das Schallrücksignal erwartet wird.
     


    Revendications

    1. Outil de diagraphie acoustique de sondage en cours de forage comprenant :

    au moins une source acoustique (201, 305, 401, 515) comprenant une pluralité d'éléments sources, dans lequel chacun de la pluralité d'éléments sources (501) est commandé indépendamment de telle sorte que la ou les sources acoustiques peuvent générer un signal acoustique multipolaire le long de différentes orientations par rapport à l'outil ;

    au moins un récepteur acoustique (207, 307, 407) comprenant une pluralité d'éléments de détection acoustique (705) ;

    caractérisé par une pluralité de capteurs (301) configurés pour déterminer un angle de face d'outil instantané pendant que l'outil est en rotation dans le trou de forage ;

    une commande de tir de sources (303) configurée pour utiliser l'angle de face d'outil instantané pour commander un tir de la pluralité d'éléments sources pendant que l'outil est en rotation dans le trou de forage, la commande étant telle qu'une direction du signal acoustique multipolaire généré par la source acoustique est géostationnaire et présente une ou plusieurs directions géostationnaires prédéterminées ; et

    une électronique d'enregistrement de récepteur (211) configurée pour enregistrer indépendamment des signaux de détection provenant de chacun de la pluralité d'éléments de détection acoustique (705) conjointement avec l'angle instantané de face de l'outil.


     
    2. Outil de diagraphie acoustique de sondage en cours de forage selon la revendication 1, dans lequel la pluralité d'éléments sources est répartie autour d'une circonférence de masse-tige d'outil.
     
    3. Outil de diagraphie acoustique de sondage en cours de forage selon la revendication 1 ou la revendication 2, dans lequel le signal acoustique multipolaire étant un signal unipolaire, dipôle ou quadripôle.
     
    4. Outil de diagraphie acoustique de sondage en cours de forage selon l'une quelconque des revendications 1 à 3, dans lequel la pluralité de capteurs est une combinaison d'accéléromètre, de gyroscope et de magnétomètre.
     
    5. Outil de diagraphie acoustique de sondage en cours de forage selon l'une quelconque des revendications 1 à 4, dans lequel la commande de tir de sources (303) est configurée de telle sorte que la ou les directions géostationnaires prédéterminées comprennent deux directions géostationnaires prédéterminées à 45° l'une par rapport à l'autre et la source acoustique est une source quadripôle.
     
    6. Outil de diagraphie acoustique de sondage en cours de forage selon l'une quelconque des revendications 1 à 4, dans lequel la commande de tir de sources (303) est configurée de telle sorte que la ou les directions géostationnaires prédéterminées comprennent deux directions géostationnaires prédéterminées à 90° l'une par rapport à l'autre et la source acoustique est une source dipôle.
     
    7. Outil de diagraphie acoustique de sondage en cours de forage selon l'une quelconque des revendications 1 à 6, dans lequel la pluralité d'éléments de détection est répartie autour de la paroi de masse-tige de logement de masse-tige de l'outil.
     
    8. Outil de diagraphie acoustique de sondage en cours de forage selon l'une quelconque des revendications 1 à 7, dans lequel le nombre d'éléments sources pour chacune de la ou des sources acoustiques est de quatre ou de multiples de quatre et le signal acoustique est dipôle.
     
    9. Procédé de diagraphie acoustique de sondage en cours de forage comprenant au moins une source acoustique comprenant une pluralité d'éléments sources (501 au moins un récepteur acoustique (207, 307, 407) comprenant une pluralité d'éléments de détection acoustique, et
    caractérisé par une pluralité de capteurs (301, 405) pour déterminer un angle de face d'outil instantané pendant que l'outil est en rotation dans le trou de forage, le procédé consistant à :

    capter (601,701) un angle de face d'outil instantané pendant que l'outil est en rotation dans le trou de forage ;

    moduler (603) une amplitude d'un signal de tir pour chaque élément source dans une pluralité d'éléments sources selon l'angle de face d'outil instantané de telle sorte que une direction du signal acoustique multipolaire généré par la source acoustique est commandée pour être géostationnaire et possède une ou plusieurs directions géostationnaires prédéterminées ;

    amorcer (605) le signal acoustique ; et

    enregistrer (703) indépendamment les signaux de détection provenant de chacun de la pluralité d'éléments de détection acoustique (705) conjointement avec l'angle instantané de face de l'outil.


     
    10. Procédé selon la revendication 9, dans lequel la ou les directions géostationnaires prédéterminées comprennent deux directions géostationnaires prédéterminées à 45° l'une par rapport à l'autre et dans lequel la source acoustique est une source quadripôle.
     
    11. Procédé selon la revendication 9, dans lequel la ou les directions géostationnaires prédéterminées comprennent deux directions géostationnaires prédéterminées à 90° l'une par rapport à l'autre et dans lequel la source acoustique est une source dipôle.
     
    12. Procédé selon l'une quelconque des revendications 9 à 11 comprenant en outre le traitement des signaux de détection enregistrés pour extraire des événements de diagraphie associés aux directions de source prédéterminées.
     
    13. Procédé selon l'une quelconque des revendications 9 à 12 comprenant en outre la réalisation de multiples tirs de la ou des sources acoustiques et l'empilement d'une pluralité d'événements de diagraphie associés à une ou plusieurs directions prédéterminées.
     
    14. Procédé selon l'une quelconque des revendications 9 à 13, dans lequel le ou les récepteurs servent à enregistrer un signal acoustique de retour provenant d'une caractéristique géologique et l'orientation de la ou les sources acoustiques est commandée pour pointer dans une direction dans laquelle le signal acoustique de retour est attendu.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description