Well-constrained two-dimensional seismic variable velocity field nonlinear error correction method

Abstract

The invention discloses a well-constrained two-dimensional seismic variable velocity field nonlinear error correction method which comprises the following steps: 1, performing deduction and conversion to improve and correct stack velocities of a poor data quality section and a seismic data-free section in a two-dimensional work area, and performing polynomial fitting on all the stack velocities on grid points to establish an initial stack velocity field; 2, generating an average wellhead velocity; 3, constructing an error function, namely making an error curve of a well side stack velocity and the average wellhead velocity, and an error curve of the well side stack velocity and a non-well side seismic channel stack velocity; 4, performing error correction on the seismic stack velocities in the grid points to establish a more reasonable and more accurate variable velocity field by taking nonlinearly variable function values obtained in step 3 as correcting values; 5, performing time-depth conversion on an interpretation time horizon to realize variable velocity mapping by utilizing a corrected variable velocity average velocity model. According to the method, errors of the variable velocity field are favorably reduced, so that the variable velocity mapping accuracy is improved.

Description

technical field [0001] The invention belongs to the field of oil and gas exploration, and relates to a nonlinear error correction method for a well-constrained two-dimensional seismic variable velocity field. Background technique [0002] Seismic velocity is one of the most important parameters in seismic exploration. Establishing a variable velocity field and realizing the variable velocity mapping in the time-depth conversion is one of the important methods to obtain the final results of seismic exploration, and one of the important changes brought by the development of computer software and hardware technology to the structural mapping. In the traditional construction of graphs, in order to reduce the workload, a region often only uses a speed ruler (that is, all points use a time-depth conversion ruler) for time-depth conversion. Obviously, there are errors between the obtained results (stratum burial depth, etc.) and the actual situation. For areas with complex structu...

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Problems solved by technology

Since it is an interpolation, there are inevitable errors between the obtained results and the actual situation, especially for areas with complex structures, such as figure 2 As shown, due to the existence of these errors, the established variable velocity field will not match the actual situation, and the accuracy of the produced structural map will be affected, which is not conducive to further exploration.

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