Amoco Corporation

Martin L Smith

Carl H Sondergeld

Paul R Gutowski

A sonic well logging system and apparatus for determination of seismic wave velocities from a seismic wave propagating in a subterranean formation about a wellbore. The system includes the process of imparting a seismic wave into the subterranean formation about the wellbore, and receiving the seismic wave after it has interacted with the subterranean formation at a plurality of semismic receivers positioned in the wellbore. The seismic waves are transformed at each of the seismic receivers into a seismic signal and these signals nonlinearly staked for a selected position in the wellbore to generate a velocity spectrum of seismic wave velocities. Coherency peaks are then selected from the velocity spectrum with each coherency peak having associated therewith a unique seismic wave velocity, such as P-wave, S-wave, tube wave and the like.

Sonic logging system

A borehole logging method and system are provided for obtaining a measure of formation anisotropy in formations adjacent the borehole. The system comprises an elongated housing for suspension within the borehole. First and second asymmetric pressure wave sources for generating shear waves directly within formations adjacent the borehole are mounted with the housing. Additionally, first and second sets of receivers are mounted with the housing for recording first and second signals representative of the earth's response to the first and second shear waves propagating in the formations adjacent the borehole, respectively. The first set of receivers have an orientation matching the first source, and the second set of receivers have an orientation matching the second source. The system further includes a processor for determining a measure of formation anisotropy from the first and second recorded signals. With a first set of source/receiver pairs having matched polarizations and azimuthal orientations, first signals, representative of the imparted acoustic shear wave energy after propagation through a portion of the formations adjacent the borehole, are recorded. With a second set of source/receiver pairs having matched polarizations and azimuthal orientations different from the first set of source/receiver pairs, second signals, representative of the imparted acoustic shear wave energy after propagation through a portion of the formations adjacent the borehole, are recorded. The first and second recorded signals can be processed for events representative of first and second shear wavefront arrivals of the imparted acoustic shear wave energy. Formation anisotropy can be characterized with measures of the events representative of the first and second shear wave arrivals in the first and second recorded signals.

Acoustic well logging method and system for obtaining a measure of

A sonic well logging system and apparatus for determination of seismic wave velocities from a seismic wave propagating in a subterranean formation about a wellbore. The system includes the process of imparting a seismic wave into the subterranean formation about the wellbore, and receiving the seismic wave after it has interacted with the subterranean formation at a plurality of seismic receivers positioned in the wellbore. The seismic waves are transformed at each of the seismic receivers into a seismic signal and these signals nonlinearly stacked for a selected position in the wellbore to generate a velocity spectrum of seismic wave velocities. Coherency peaks are then selected from the velocity spectrum with each coherency peak having associated therewith a unique seismic wave velocity, such as P-wave, S-wave, tube wave and the like.

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Broken Arrow, OK, United States of America

Martin L Smith