Variable-offset VSP data time difference correction method

Abstract

The invention provides a variable-offset VSP data time difference correction method and belongs to the field of earthquake data processing. The method includes the following steps: (1) decompiling acquired original variable-offset VSP data so that three-component wave field data is obtained; (2) inputting a shallow replacement speed V<replacement> and an earthquake processing base level elevation Z<base level>, which are used in processing of ground earthquake data of an area which a VSP observation well is in; (3) picking up first-arrival times of direct waves on vertical components z of offsets so that time-depth data T<0> (n, L<K>) is obtained; (4) calculating a time difference in a single offset; (5) calculating inter-offset time differences; (6) correcting a total time difference; (7) analyzing correction error; (8)ending. The method improves the original wave field quality of the variable-offset VSP data and provides accurate basic data for further effective application of the variable-offset VSP data.

Description

technical field [0001] The invention belongs to the field of seismic data processing, and in particular relates to a method for correcting time difference of variable offset VSP data. Background technique [0002] The actual non-zero offset VSP observation is limited by the number of receiving geophones in the well, and the VSP observation needs to upgrade the geophone multiple times and complete the observation of the entire well section by group shot excitation. Multiple (variable) offset distance VSP data are obtained by excitation with explosive source and multi-well group shots. Influenced by factors such as the elevation of the well and the offset of the excitation well, there is a time difference at each depth point of the receiving wave field; Large, there is a time difference between the wave fields at different offsets. Due to many geological and non-geological factors, no time difference correction or insufficient time difference correction accuracy for variable...

AI Technical Summary

Problems solved by technology

Due to many geological and non-geological factors, no time difference correction or insufficient time difference correction accuracy for variable offset VSP data will distort the original wave field information to varying degrees, which will affect the subsequent variable offset VSP wave field. The effective use of information such as reflected waves and converted waves affects the reliability of identifying structural details around the wellbore and reservoir problems

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