四川东部高陡构造的归位处理研究

ON MIGRATION FOR SEISMIC DATA OBTAINED FROM STEEP STRUCTURE , EASTERN SICHUAN PROVINCE

四川东部高陡构造由于地表和地下地层陡峻、断层众多和速度横向变化急剧,造成在叠加剖面上的复杂面貌。正确的归位处理则是搞准构造形态的关键。横向变速∫-k偏移和层速度时深转换两步归位处理的效果,主要取于所建立的偏移速度模型和时深转换速度模型的正确、合理性。波组分离校正偏移是针对f-k偏移局限性而提出的一种改进设想。射线变速深度偏移是基于射线理论以选代方式在深度域完成偏移归位的一种方法,应用于高陡构造的归位处理中见到较好效果。以横向变速f-k偏移和层速度时深转换为主,结合射线变速深度偏移和模型正演的多种归位处理方法综合应用,是进一步搞准高陡构造形态的必要措施,在四川东部大池干井构造上已见到明显效果。

Owing to the strata of the structures in eastern Sichuan Province are very steep,either outcropping or hidding,and many of them were developed with faults and great changes could be seen lateraly in velocity, along these lines, the stacked section is, in general , very complicated. In order to make clear the intrinsic shapes and positions of structures, the correct migration is ,apparently, of great importance. The effect of lateral variant velocity f-k migration and time-depth conversion by using interval velocity is mainly dependent on whether the velocity model used for migration and time-depth conversion is practical and correct. Ray-tracing depth migration with variable velocity is performed and completed in depth domain which is based OP the ray-theory and is conducted in the way of iteration. Fairly good result is achieved by applying the technique recommended to the steep structure migration. With the lateral variant velocity f-k migration and the interval velocity time-depth conversion as the main, the variant velocity ray-tracing depth migration and the forward modelling as the subsidiary, satisfactory achievements were obtained in the Dachi Gnnjing structure in the eastern part of Sichuan Province.