Method of approximating layer displacing static correct

Abstract

The invention relates to approximation layer replacing static correction method used to correct earthquake collected data in oil gas, coalfield etc. It replaces actual inhomogeneous medium by homogeneous medium close to surface structure, removes high frequency component effected superposition imaging, and keeps seismic wave field of earth surface observation to reduce the static correction influence to the minimum. It includes the following steps: collecting recorded earthquake data by general seismic prospecting; investigating and recording close earth surface structure and speed physical quantity by conventional method; calculating smooth earth surface altitude; calculating smooth low decelerating layer speed; peeling off and filling communication; finishing excursion imaging based on altitude surface and time depth conversion after section interpretation by conventional method. The invention can remove seismic wave unequal quantities time delay caused by inhomogeneous medium close to earth surface to satisfy the demand for earthquake data processing and interpretation.

Description

technical field [0001] The present invention relates to the seismic exploration technology of oil and gas, coal fields, etc., and specifically corrects the data collected by seismic data, and eliminates the unequal time delay of seismic waves caused by the near-surface heterogeneous medium, so as to meet the requirements of seismic data processing and interpretation. Replace statics method. Background technique [0002] At present, the two-step method used for the static correction processing of the acquired seismic data decomposes the base level static correction into high-frequency components and low-frequency components, which are applied in pre-stack and post-stack respectively. In this way, there are two datum planes in the processed seismic section: one is the time zero line finally corrected; the other is the common midpoint (CMP) reference plane. The time zero line represents a datum that actually exists in space and has an exact elevation. Since the low-frequency c...

AI Technical Summary

Problems solved by technology

But the CMP reference plane is a time reference plane, and there is no exact elevation in space after turning deep

In addition, the time zero line has an exact elevation but the datum plane of the velocity field does not correspond to it; the CMP reference plane corresponds to the datum plane of the velocity field but has no exact elevation

[0003] In actual work, there are two methods of depth conversion: 1. Starting from the CMP reference plane, it is considered that the CMP reference plane is the smooth surface of the earth's surface. After deepening, replace the CMP reference plane with the smooth surface of the earth's surface, or directly multiply the low-frequency component by the fill speed, the resulting errors have a greater impact on high-precision exploration and the search for low-amplitude structures

2. Go deep on the zero line of time, and correct the velocity field to the same datum plane at the same time. After doing so, the actual depth difference will be larger. The main problem lies in the conversion of the speed field datum plane, because the number of times the shallow layer is covered Low, low signal-to-noise ratio, it is difficult to analyze the velocity accurately, resulting in errors in the velocity field

The CMP reference surface is a time correction quantity affected by the comprehensive influence of the surface model, which not only includes the influence of the surface elevation, but also includes the influence of the lateral change of the velocity of the low-velocity zone and the change of the bottom boundary of the low-velocity zone. It is irreversible, so the existing method cannot accurately calculate the corresponding elevation

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