Pre-stack Seismic AVA Inversion Method Research And Application Of Sandstone Gas-bearing Reservoir

With the continuous exploration of oil and gas resources,the exploitation of oil and gas reservoirs has transitioned from tectonic type to hidden complex type,and seismic prediction technology has also transitioned from post-stack inversion of single inversion result parameters to pre-stack inversion of multiple inversion result parameters.AVA inversion is an effective pre-stack inversion technique,which uses the change information of seismic amplitude with incident angle / shot-off distance,inversion to obtain parameters such as vertical and horizontal wave velocity and density,and then to identify underground lithology and detect underground Oil and gas.The Zoeppritz equation is the basis of the forward theory of AVA inversion.The simple and easy-to-use Zoeppritz equation approximations are varied,but when the incident angle is large,the Zoeppritz equation approximation will be biased.In recent years,many gas fields have been discovered around the diapir zone and the periphery of the Yinggehai Basin,but there is still no major breakthrough in the exploration of the slope zone.Due to the special geological conditions and data basis,gravity flow sandstone reservoirs in this area urgently need to explore effective sandstone gas reservoirs.Layer prediction technology.Therefore,from the perspective of practical application,this article introduces the Zoeppritz equation and its approximate expressions,compares their accuracy,and derives a generalized linear pre-stack inversion algorithm based on the Zoeppritz equation under the Bayesian framework.Combined with the rock physics analysis technology,on the basis of the prediction of the space-time distribution of the sand body after the post-stack inversion,the pre-stack data analysis is carried out,and the pre-stack inversion method is used to invert the vertical and horizontal wave velocity and density,and the oil and gas sensitivity factors are optimized.To conduct fluid detection and predict the distribution of gas-bearing sandstones,which provides a basis for the region to select favorable exploration targets.