Adaptive anti-dispersion block space-time bivariable reverse time migration method

Abstract

The invention relates to an adaptive anti-dispersion block space-time bivariable reverse time migration method, which comprises the following steps: 1) carrying out variable mesh division on a calculation area covered by an observation system to obtain space meshes; 2) carrying out variable processing on the space meshes through a variable mesh method, and meanwhile, considering change of time step; 3) processing wave field values of edge points in a variable mesh transition region through a Lanczos filtering method; 4) carrying out positive extrapolation of a source wave field on the calculation area covered by the observation system by utilizing a block space-time bivariable algorithm and according to a reverse time migration process and storing the source wave field; 5) carrying out reverse extrapolation of a detection wave field on the calculation area by utilizing the same block space-time bivariable algorithm and storing the detection wave field; and 6) based on a cross-correlation imaging condition, carrying out relevant imaging on the extrapolated source wave field and the detection wave field, and carrying out post-stack data processing of conventional stacking and Laplacefiltering and the like on the imaging results to obtain a final reverse time migration result.

Description

technical field [0001] The invention relates to a reverse time migration method, in particular to an adaptive anti-dispersion block time-space double-variable reverse time migration method. Background technique [0002] The general finite-difference seismic reverse time migration method is based on a regular grid in a Cartesian coordinate system and is an effective method for dealing with inhomogeneous media. However, with the social industry's increasing demand for oil and gas resources, the geological conditions faced by seismic exploration are becoming more and more complex, including areas with strong vertical and horizontal velocity changes, low velocity zones, complex structural areas, and small pores, fractures, and caves in carbonate reservoirs. When processing the seismic data in these areas, in order to ensure the calculation accuracy and stability, the grid spacing must be made very small, which will lead to an increase in the storage capacity and calculation amou...

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Problems solved by technology

For example, there may be a near-surface low-velocity zone and a deep underground low-velocity body at the same time. At this time, if the unified variable mesh algorithm is still used, it will cause oversampling of the high-speed area between the low-velocity bodies, reducing the simulation efficiency; and, When the speeds of two low-velocity bodies are different, different grid change multiples are required, and the uniform variable grid needs to determine the variable grid multiples according to the lower-velocity low-velocity body, which will cause another low-velocity volume oversampling

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