Two-dimensional correction method for closing error of stacking velocity and root-mean-square velocity field

Abstract

The invention relates to a two-dimensional two-step correction method of a stacking velocity and a root-mean-square velocity field, which comprises the steps of: firstly, acquiring the time difference delta T of each measuring line before correcting a T0 curve surface and a T0 in a closing way; correcting the stacking velocity with the delta T on reference plane, wherein when the delta T is larger than 0, a correction velocity uses a ground surface filling velocity, and when the delta T is less than 0, the correction velocity uses a velocity on a velocity spectrum; and aiming at the root-mean-square velocity closing error caused by apparent dip when the stacking velocity is converted into the root-mean-square velocity, firstly obtaining the time gradient of the stacking profile of a main measuring line and a communication measuring line, acquiring the apparent dip and the root-mean-square velocity of the directions of the different measuring lines, calculating the weighting coefficient at the point of intersection, interpolating and normalizing the weighting coefficient at the point of intersection, and stacking the root-mean-square velocity of the main measuring line and the communication line in a weighting way to obtain a final root-mean-square velocity field with the weighting coefficient of the directions of the different measuring lines. The method scientifically and effectively eliminates the closing error of the velocity of the intersected measuring lines, and improves the precision of the velocity field of a two-dimensional earthquake work area.

Description

Technical field: [0001] The invention relates to a method for correcting superposition velocity and root mean square velocity field accuracy of two-dimensional seismic work area velocity field construction in low-amplitude structural trap petroleum seismic exploration. Background technique: [0002] In the data interpretation and variable-velocity mapping work in the 2D seismic work area, there are generally problems of time and velocity field closure gaps in the reflection layer at the intersection points of the survey lines. At present, the research on the time closure problem of the reflective layer at the intersection of survey lines is relatively in-depth, but the research on the velocity field closure problem is still rare. More representative ones are Zuo Longping et al. who proposed in 2000 to calculate the correction operator for different survey lines, and perform time-varying and space-varying time difference correction and waveform correction on the intersection ...

AI Technical Summary

Problems solved by technology

However, none of them started from the root cause of the poor closure to solve the problem, and there are inevitably limitations: ①The speed closure caused by various reasons is implemented across the board, and the accuracy is bound to be restricted by one-time correction; ②All use mathematics The method of curve fitting, the former uses a fitting function, the latter is a multi-segment fitting, which reduces the accuracy of the superposition (average) velocity, and also reduces the accuracy of the calculation of the closure difference; Correction of stacking velocity is only suitable for small formation dip angles; the latter method may cause velocity closure problems when fitting the velocity vertically in segments, and this method can only be used for large sets of formations, and the accuracy is limited

Previous studies did not start with the root cause of the velocity closure difference, trying to solve geophysical problems thoroughly by using purely mathematical methods, and there are inevitably various defects

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