High-Precision Velocity Modeling Technology of Subsalt Structure and its Application in Deep Carbonate Imaging

Abstract

Summary Subsalt oil and gas reservoirs are mainly distributed in the Gulf of Mexico, West Africa Coast Basin, Beach Basin and other basins abroad, and are mainly distributed in the Tarim Basin, Sichuan Basin, Ordos Basin and other regions in western China, which have huge resource potential. Gypsum salt rocks are well developed in Chinese marine strata. Due to the large velocity difference between gypsum rock and surrounding rock, the seismic wave field is complex. At the same time, due to the dramatic lateral variation of gypsum-salt rock thickness, there is a large difference in the travel time of the, which make conventional pre-stack time migration imaging unable to reasonably solve and describe real geological phenomena. On the basis of wide-azimuth seismic data acquisition, through the development of multi-information constrained seismic velocity modeling technology, grid tomography velocity optimization technology, subsalt structural geological model constrained modeling technology and TTI anisotropic pre-stack depth migration technology, the distortion effect of gypsum-salt rock on underlying strata is well restored, the structural morphology of subsalt carbonate rock is restored, the imaging quality is significantly improved, and the well-seismic coincidence degree is higher, which provides high-quality data for the exploration and development of subsalt carbonate reservoirs.