Quadrupole acoustic shear wave logging while drilling
AssigneeSchlumberger Technology Corporation
InventorsChaur-Jian Hsu, Jahir A. Pabon, Bikash K. Sinha, Sergey Asvadurov
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Abstract
A tool generates signals indicative a shear wave slowness of the formation surrounding a borehole. The tool comprises a collar portion adapted for mounting in a drill string, a quadrupole sonic transmitter mounted to the collar portion, and a quadrupole sonic receiver array mounted to the collar spaced apart from the transmitter. A method determines shear wave slowness of the formation. The method includes propagating quadrupole wave energy into the formation and detecting quadrupole dispersive waveform received at a second location. Formation shear wave slowness is calculated using dispersive slowness time coherence processing.
Claims28
A tool for generating signals indicative of shear wave slowness of the formation surrounding a borehole containing a fluid and a drill string, the tool adapted for use with a drill string having a plurality of drill collars jointed together, the tool comprising:
- a collar portion defining an axis and adapted for mounting in a drill string;
- a sonic transmitter mounted to the collar portion at a first location, wherein said transmitter excites quadrupole signals as well as other order modes;
- and
- a sonic receiver array mounted to the collar portion at a second location, the second location spaced apart from the first location, wherein said receiver is capable of distinguishing quadrupole signals from other order modes.
A quadrupole sonic receiver, for use in a tool for generating signals indicative of shear wave slowness of the formation surrounding a borehole containing a fluid and a drill string, the tool adapted for use in a drill string having a plurality of drill collars jointed together, said tool having a collar portion defining an axis, said quadrupole sonic receiver having an azimuthal array of four equally spaced transducer quadrants, each quadrant including at least one electro-acoustical transducer element, wherein said receiver is capable of distinguishing quadrupole signals from other order modes.
A system for determining shear wave slowness of the formation surrounding a borehole, the borehole containing a fluid, the system comprising:
- a tool for generating signals indicative of formation shear wave slowness, the tool having a collar portion defining an axis and adapted for mounting in a drill string, a sonic transmitter mounted to the collar portion at a first location, wherein said transmitter excites quadrupole signals as well as other modes, and a quadrupole sonic receiver array mounted to the collar portion at a second location, the second location spaced apart from the first location, wherein said receiver is capable of distinguishing quadrupole signals from other order modes;
- and
- computing means for calculating formation shear wave slowness from said signals.
A method for determining shear wave slowness of the formation surrounding a borehole containing a drill string and a fluid, the method comprising:
- propagating quadrupole wave energy into the formation from a first location on the drill string;
- detecting quadrupole dispersive waveforms and other order modes at a second location on the drill string at a distance from the first location to obtain digital data indicative of shear wave slowness of the formation;
- calculating formation shear wave slowness from said digital data, and
- storing said calculated data.
Dependencies are inferred from the claim text.