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Method and apparatus for multipole acoustic wave borehole logging

Patent ·
OSTI ID:6681434
A method is described for determining the radial thickness of an invaded zone of an earth formation surrounding a borehole where a virgin earth formation surrounds the borehole and is separated from the borehole by the invaded zone. The method comprises: (a) transmitting a 2/sup n/-pole P-wave from a point in the borehole into the earth formation surrounding the borehole, n being an integer greater than zero; (b) measuring the P-wave velocity of a zone of the earth formation located at a first radial distance from the borehole by detecting the arrival of the 2/sup n/-pole P-wave at a first location and at a second location in the borehole spaced longitudinally along the borehole from the point of transmission and from each other. The second location is spaced farther from the point of transmission than is the first location, the time arrival between the detections of the 2/sup n/-pole P-wave arrival is measured at the first location and the second location; and (c) repeating the steps (a) and (b) with successively increased longitudinal spacings between the point of transmission and the first location and between the point of transmission and the second location to measure the P-wave velocities of zones of the earth formation located successively radially farther away from the borehole.
Assignee:
Exxon Production Research Co., Houston, TX
Patent Number(s):
US 4649526
OSTI ID:
6681434
Country of Publication:
United States
Language:
English