Near-surface modeling method using tomography inversion of two-step method

Abstract

The invention relates to a near-surface modeling method using tomography inversion of a two-step method. The near-surface modeling method specifically comprises the following steps of: (1) picking and inputting short-refraction first-break; (2) carrying out tomography inversion on the short-refraction first-break and outputting explanation results capable of reflecting fine velocity change in an extremely shallow stratum as shown in picture 2; (3) picking a big shot and recording first-break time; (4) interpolating short-refraction inversion results in combination with explanation results of a microlog in a work area by using a kriging method and building near-surface velocity body of the extremely shadow stratum; (5) meshing and constraining inversion initial-velocity modeling, replacing a near-surface velocity body at the extremely shallow stratum obtained in the last step into the shallow stratum part of the initial model generated at the big-shot first-break, replenishing the velocity loss of the extremely shallow stratum resulting from the excessive minimum offset distance of the big shot; (6) constraining generation of a weight field; and (7) inversing the near-surface velocity model by using a constrained chromatography method, picking the top interface of a high-speed layer on the basis of a velocity-depth model obtained by tomography inversion, and calculating static correcting values of a shot point and a geophone position.

Description

technical field [0001] The invention belongs to the technical field of seismic data processing and interpretation in petroleum seismic exploration, and specifically relates to a two-step tomographic inversion near-surface modeling method for obtaining surface velocity by a two-step tomographic inversion near-method. Background technique [0002] In the field of petroleum seismic exploration, the existence of the near-surface low-velocity zone causes the problem of static correction, which leads to the inability of the seismic profile to accurately reflect the shape of the underground geological structure. Therefore, it is necessary to eliminate the low-velocity zone during seismic data processing. Statics problem. [0003] In order to solve the problem of static correction, it is necessary to obtain the near-surface depth-velocity model, which is mainly obtained by two methods, one is obtained by the small refraction method of field investigation, and the other is obtained b...

AI Technical Summary

Problems solved by technology

The method provided by the invention combines the advantages of different methods, improves the accuracy of near-surface modeling and the rationality of the obtained static correction, and solves the problem of fine near-surface modeling under complex surface conditions, effectively improving the accuracy of complex surface modeling. The imaging quality of seismic sections under topographic conditions ensures the reliability of structural forms

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