Abstract:

The southeastern Sichuan region has large elevation differences, complex surface conditions, large stratum dip, and complex conditions underground, so that the accurate imaging is difficult. In the support of shale gas exploration and development, there are problems of inconsistent well seismic wave group occurrence, false faults and well seismic prediction errors for the pre-processed data in this area. Aiming at these problems, the well-control anisotropic pre-stack depth migration method is proposed and applied to the above three-dimensional work area. By improving the accuracy of the velocity model, the seismic imaging accuracy of the complex fold area is improved, and it plays an important role in guiding the later well position, and improving the high-quality shale drilling rate. In this paper, the accuracy of the migration velocity model is finely characterized from two aspects: isotropy and anisotropy. Through the deep research and practice of high-precision grid tomography velocity modeling, travel（TPT）and TTI（transverse isotropic media with axial inclined symmetry）, the key technology series of seismic precision imaging in southeast Sichuan is gradually improved to enhance the well seismic yield consistency, reduce the well earthquake depth prediction error, eliminate the fault illusion of seismic profile, and provide important technical support for subsequent exploration and development of shale gas deployment.

Key words: grid tomographic, anisotropy, TPT, TTI anisotropic imaging, Nanchuan area