Measurement-while-drilling acoustic system employing multiple, segmented transmitters and receivers
First Claim
1. A measurement-while-drilling (MWD) tool conveyed on a drilling tubular for use during drilling of a wellbore in a formation, comprising:
- (a) a tool body;
(b) at least one transmitter array carried by the tool body, said at least one transmitter array including a first plurality of spaced apart transmitter elements circumferentially disposed about the tool body, each said transmitter element adapted to propagate acoustic into the formation;
(c) at least one receiver array containing a second plurality of circumferentially disposed receiver elements, said at least one receiver array carried by the tool body and axially spaced apart from the at least one transmitter array;
(d) a processor adapted for selectively activating a subset of the plurality of transmitter elements simultaneously at at least one time to excite said acoustic waves in the formation and processing the response of at least one receiver element on the at least one receiver array to said acoustic waves to determine a parameter of interest, wherein said acoustic waves have a mode that is at least one of the group consisting of;
a compressional (“
P”
) wave excited in a dipole mode, a shear (“
S”
) wave excited in a dipole mode, a P wave excited in a quadrupole mode, an S wave excited in a quadrupole mode, a P wave excited in an octupole mode, and an S wave excited in an octupole mode.
1 Assignment
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Accused Products
Abstract
An acoustic MWD system comprises at least one transmitter array and at least one receiver array spaced axially along an essentially tubular downhole subassembly. Each transmitter and receiver array includes a plurality of elements circumferentially disposed on the outside of the assembly. The downhole subassembly also comprises a processor, data storage, telemetry elements, power supplies and control circuits as well as other types of sensors. In one embodiment of the invention, the transmitters are operated as a quadrupole in orthogonal orientations and signals from two receiver elements processed to attenuate common modes (including body waves through the tool, monopole waves and Stoneley waves). In another embodiment, the transmitters are used as crossed dipoles and signals received by cross-dipole receivers may be used to determine shear wave birefringence in the formation. In yet another embodiment, the transmitters are used as crossed dipoles and a single dipole receiver produces information relating to the birefringence: rotation of the drillstring makes it possible to operate the transmitters in two orthogonal orientations.
125 Citations
28 Claims
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1. A measurement-while-drilling (MWD) tool conveyed on a drilling tubular for use during drilling of a wellbore in a formation, comprising:
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(a) a tool body;
(b) at least one transmitter array carried by the tool body, said at least one transmitter array including a first plurality of spaced apart transmitter elements circumferentially disposed about the tool body, each said transmitter element adapted to propagate acoustic into the formation;
(c) at least one receiver array containing a second plurality of circumferentially disposed receiver elements, said at least one receiver array carried by the tool body and axially spaced apart from the at least one transmitter array;
(d) a processor adapted for selectively activating a subset of the plurality of transmitter elements simultaneously at at least one time to excite said acoustic waves in the formation and processing the response of at least one receiver element on the at least one receiver array to said acoustic waves to determine a parameter of interest, wherein said acoustic waves have a mode that is at least one of the group consisting of;
a compressional (“
P”
) wave excited in a dipole mode, a shear (“
S”
) wave excited in a dipole mode, a P wave excited in a quadrupole mode, an S wave excited in a quadrupole mode, a P wave excited in an octupole mode, and an S wave excited in an octupole mode.- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A method of determining a parameter of interest of a subsurface formation during drilling of a wellbore by a drill bit carried on a drilling tubular in the formation, comprising:
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(a) conveying a measurement-while-drilling (MWD) device on the drilling tubular into the borehole;
(b) using at least one transmitter array carried by the tool body, said at least one transmitter array including a first plurality of spaced apart transmitter elements circumferentially disposed about the tool body, for propagating seismic waves into the formation;
(c) using at least one receiver array axially spaced apart from the at least one transmitter array, said at least one receiver array containing a second plurality of circumferentially disposed receiver elements, for receiving a portion of said seismic waves and providing signals indicative thereof; and
(d) using a processor for activating a subset of the plurality of transmitter elements simultaneously at at least one time and processing said signals to determine a parameter of interest, wherein said seismic waves have a mode that is at least one of the group consisting of;
a compressional (“
P”
) wave excited in a dipole mode, a shear (“
S”
) wave excited in a dipole mode, a P wave excited in a quadrupole mode, an S wave excited in a quadrupole mode, a P wave excited in an octupole mode, and an S wave excited in an octupole mode.- View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27)
(i) operating a first of the pair of crossed transmitter dipoles at a first time at a first azimuthal orientation of the MWD tool, (ii) operating a second of the pair of crossed transmitter at a second time at a second azimuthal orientation of the tool substantially equal to the first azimuthal orientation of the tool, (iii) rotating the MWD tool on the drilling tubular and operating a first pair of the pair of crossed transmitter dipoles at a third time at a third azimuthal orientation of the MWD tool substantially orthogonal to the first and second azimuthal orientations, and (iv) operating a second of the pair of crossed transmitter at a fourth time at a fourth azimuthal orientation of the tool substantially equal to the third azimuthal orientation of the tool.
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27. The method of claim 26 further comprising:
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(A) using an orientation sensor on the MWD tool to determine an orientation thereof and providing a signal indicative of said orientation, and (B) using the processor to operate the pair of transmitter dipoles at said first, second, third and fourth times in response to said signal.
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28. A measurement-while-drilling (MWD) tool for use during drilling of a wellbore having a longitudinal axis in a formation having a reflecting interface, comprising:
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(a) a tool body;
(b) a plurality of spaced apart transmitter arrays carried by the tool body, each said transmitter array containing a plurality of spaced apart transmitter elements circumferentially disposed about the tool body, each said transmitter element adapted to propagate acoustic energy into a formation surrounding the wellbore;
(c) at least one receiver axially spaced apart from the plurality of transmitter arrays on the tool body, said receiver detecting acoustic energy traveling through the formation in response to the acoustic energy transmitted by said transmitter elements; and
(d) a processor including a model of at least one of (i) response characteristics of said at least one receiver, and, (ii) data defining a target formation of interest;
said processor selectively activating a plurality of the transmitter elements to focus acoustic energy into the formation in a selected direction towards the reflecting interface and processing the responses of the at least one receiver using said model to determine a parameter of interest.
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Specification