Method for eliminating orientation uncertainty of geologic body outside well based on eccentric measurement of dipole acoustic logging instrument

Abstract

The invention discloses a method for eliminating out-of-well geologic body orientation uncertainty based on eccentric measurement of a dipole acoustic logging instrument, and the method mainly comprises the steps: carrying out the eccentric measurement of an orthogonal dipole acoustic logging instrument in a well, separating out an out-of-well reflection signal from collected four-component data, and carrying out the migration imaging; forming a synthetic signal SH transmitted and received in the phi direction by using the four-component reflected signals, and changing the phi value to obtain an angle phi0 when the SH reaches the maximum amplitude; synthesizing signals Ns1 and Ns2 by using the four-component reflection data, and comparing phase differences of the signals Ns1 and Ns2; establishing a law chart that the phase difference between the Ns1 and the Ns2 changes along with the orientation of the reflector; judging the real orientation of the reflector and converting the real orientation to a fixed coordinate system; and carrying out migration imaging on the maximum amplitude signal SH (phi0), and determining the distance from the reflector to the well. According to the method, the azimuth 180-degree uncertainty in dipole transverse wave far detection is eliminated through eccentric measurement of an existing instrument, and the economical efficiency and the practicability are high; and the amplitude and phase information in the four-component reflection signal is comprehensively utilized, so that the processing result is more accurate.

Description

technical field [0001] The invention belongs to the field of applied geophysical acoustic logging. Specifically, the present invention proposes a method for measuring the amplitude and phase of a four-component reflected signal according to the eccentricity by placing the existing orthogonal dipole acoustic logging tool eccentrically in the well. The method of accurately detecting the position of the geological body outside the well effectively eliminates the azimuth 180° uncertainty existing in the dipole shear wave far detection. Background technique [0002] Dipole shear wave remote detection technology is one of the important progresses in the field of oil and gas exploration and development in recent years. This technology radiates shear waves to the formation through the dipole sound source in the liquid-filled well, and receives the shear waves reflected back by the geological body outside the well. Zhou Xingxiang (Tang, X.M., 2004, Imaging near-borehole structure usi...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a method based on the eccentric measurement of the dipole acoustic logging tool to eliminate the uncertainty of the orientation of the geological body outside the well, so as to solve the problem of not changing the internal structure of the existing orthogonal dipole acoustic logging tool. Only through eccentricity measurement, the method of accurately detecting the position of the geological structure outside the well according to the amplitude and phase characteristics of the four-component reflection signal can economically and effectively solve the technical problem of 180° uncertainty in the azimuth in the long-distance detection of dipole shear waves

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