Multidirectional tomographic velocity modeling method within common offset and common azimuth domains

Abstract

The invention provides a multidirectional tomographic velocity modeling method within common offset and common azimuth domains, and belongs to the technical field of oil exploration fracture prediction. The method comprises the following steps: performing conventional processing on seismic data in a work area to establish an initial velocity model; performing pre-stack migration on the common offset and common azimuth domains by using the initial velocity model, wherein azimuth information exists in migrated CRP (Common Reflection Point) gathers; determining a position partition scheme according to a development direction of a main fracture in the work area, and segmenting the CRP gathers into n groups of sub-CRP gathers according to the azimuth information in the CRP gathers; respectively performing residual moveout (RMO) pick-up on each sub-CRP gather; uniformly performing ray tracing and tomographic inversion on all position RMO picking values to obtain an updated amount of the velocity model; using the updated amount to update the initial velocity model to obtain a new velocity model; performing a new round of pre-stack depth migration velocity model iteration till the velocity model can meet requirements.

Description

technical field [0001] The invention relates to a multi-azimuth tomographic velocity modeling method in the domain of common offset and common azimuth, and belongs to the technical field of petroleum exploration seismic data processing. Background technique [0002] Prestack depth migration velocity modeling is the core of prestack depth migration processing. At present, the most mature and widely used velocity modeling process in the industry is based on the flattening degree of the migrated CRP gather, using ray-tracing tomography to invert the remaining time difference, so as to update the velocity model, and then use the new velocity Do a new round of pre-stack depth migration until the CRP gathers are flattened. However, since the conventional prestack depth migration is performed in the common offset domain, the directionality of the offset is not considered, so the CRP gathers generated by it for velocity iterative inversion must also have no directionality. All off...

AI Technical Summary

Problems solved by technology

This scheme is indeed feasible, but the potential problem is that if the number of coverage in the sector is limited, the imaging will often be poor. If the sector is expanded, the azimuth anisotropy analysis will be inaccurate. If the binning is expanded to form a super gather, the accuracy will be affected.

It has high requirements on the original collected data, and the workload of sub-azimuth migration is huge, so the practical application is greatly limited

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