Selection method of sound source frequency in dipole transverse wave well logging of bushing well

Abstract

The present invention relates to a method for selecting sound source frequency, used in the cased-hole dipole shear wave acoustic log. Said invention is characterized by that said method includes the following steps: firstly, utilizing acoustic moveout curve to give out compressional wave velocity of said well: then utilizing velocity field equation under the column coordinate and boundarg connection condition under the condition of cased-hole and adopting three-dimensional velocity-stress finite difference method to numerically simulate the dipole acoustic all-wave wave field of oil-water well, then utilizing the quick and slow flexural waves obtained by means of numerical simulation under the condition of that the circumference of cased-hole has abonormal stress to make dispersion analysis; then utilizing the freguency of cross point of quick and slow flexural waves to define main frequency of sound source.

Description

Technical field: [0001] The invention relates to a method for selecting a sound source when using dipole shear wave logging in the field of oil field logging, in particular to a method for determining the frequency of sound source when performing dipole shear wave logging in a cased well a method of Background technique: [0002] At present, the casing damage of oil and water wells is a common concern of oilfields at home and abroad. Oilfields suffer great losses due to casing damage. Predicting and preventing casing damage has become a common concern in the fields of petroleum engineering and well logging. In recent years, the research on casing damage has found that, except casing mechanical damage and fluid corrosion caused by unpredictable downhole operations, casing damage caused by other reasons is related to abnormal stress changes around the well. key to loss forecasting. At present, the research on in-situ stress detection in oil and water wells at home and abroad...

AI Technical Summary

Problems solved by technology

[0003] In order to overcome the imperfections existing in the research on the abnormal ground stress detection in the existing cased well, that is, the inability to select the cross-dipole logging frequency under different surrounding rock conditions in the cased well, the present invention provides a The method is suitable for determining the cross-dipole shear wave logging parameters of cased wells. By applying this method, the cross-dipole logging frequency under different surrounding rock conditions in cased wells can be correctly selected, and it can also be used in cased wells. Non-destructive measurement of casing damage by inversion of abnormal ground stress around wellbore with cross-dipole acoustic logging data

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