Acoustic Anisotropy and Imaging by Means of High Resolution Azimuthal Sampling
AssigneeHalliburton Energy Services, Inc.
InventorsJennifer Anne Market, Gary Althoff
Life of this patent
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Abstract
In an acoustic logging system utilizing one or more acoustic sources, each with a specified radiation pattern around a source orientation, an acoustic signal is transmitted into a formation with a source oriented in a first source orientation. An acoustic waveform is received in response with a receiver oriented in a first direction. The slowness of the formation in the first direction is calculated using the received acoustic waveform.
Claims20
A method for determining an acoustic anisotropy of a subterranean formation, the method comprising:
- (a) rotating an acoustic logging while drilling tool in a borehole, the tool including at least one acoustic transmitter and a linear array of longitudinally spaced acoustic receivers longitudinally spaced apart from the transmitter;
- (b) measuring an acoustic wave slowness of the formation at three or more toolface angles while rotating the tool in (a);
- (c) fitting the acoustic wave slownesses measured in (b) to a mathematical model to obtain a maximum slowness and a minimum slowness;
- and
- (d) processing the maximum slowness and the minimum slowness obtained in (c) to determine the acoustic anisotropy of the subterranean formation.
A method for determining shear anisotropy in a subterranean formation, the method comprising:
- (a) rotating an acoustic logging while drilling tool in a borehole, the tool including at least one acoustic transmitter and a linear array of longitudinally spaced acoustic receivers longitudinally spaced apart from the transmitter;
- (b) measuring guided wave slownesses at three or more toolface angles while rotating the tool in (a);
- (c) fitting the guided wave slownesses measured in (b) to a mathematical model to obtain a maximum guided wave slowness and a minimum guided wave slowness;
- (d) applying dispersion corrections to the maximum and minimum guided wave slownesses to obtain maximum and minimum shear wave slownesses;
- and (e) processing the maximum and minimum shear wave slownesses to determine the shear anisotropy of the subterranean formation.
A method for determining a shear anisotropy of a subterranean formation, the method comprising:
- (a) rotating an acoustic logging while drilling tool in a borehole, the tool including at least one unipole acoustic transmitter and a linear array of longitudinally spaced unipole acoustic receivers longitudinally spaced apart from the transmitter;
- (b) measuring guided wave slownesses at three or more toolface angles while rotating the tool in (a);
- (c) applying dispersion corrections to the guided wave slownesses measured in (b) to obtain corresponding shear slownesses;
- (d) fitting the shear slownesses obtain in (c) to a mathematical model to obtain a maximum shear slowness and a minimum shear slowness;
- and
- (e) processing the maximum and the minimum shear slownesses to determine the shear anisotropy of the subterranean formation.
Dependencies are inferred from the claim text.