The Research Of Pre-stack Inversion Method Based On Core Driven

The geology of oil and gas exploration at home and abroad has become more complex and the development situation has become increasingly severe.The focus of oil and gas exploration is gradually transferred from structural trap to lithologic circle,and the focus of seismic exploration also turns to reservoir and even fluid.The study of rock physics is the basis of reservoir prediction,and seismic inversion is the core of reservoir prediction.Under the guidance of rock physics theory,the inversion of lithologic identification factor and reservoir type prediction can be realized by using pre stack seismic data.The extraction and analysis of reservoir sensitivity parameters based on core experiment is of guiding significance for seismic data inversion and reservoir prediction,which lays the rock physical data base for the exploration of oil and gas reservoirs and seismic data processing and interpretation in the study area.The reservoir of Dagang actual work area has the characteristics of thin thickness,large change,and seismic reflection of sand body and mudstone,which brings great difficulty to the identification and description of sand body.In view of the geophysical characteristics of the effective reservoir in Dagang Oilfield,the sensitive lithologic identification factor F of the reservoir is selected first from the core test measurement.Secondly,according to the seismic logging data of the study area,the elastic modulus of the dry rock skeleton is calculated by the Xu-White model,and then the Gassmann equation is used to calculate the volume modulus and shear modulus of the fluid saturated rock,and then the shear wave prediction is realized.Finally,the Zoeppritz equation is derived,and a new AVO approximation formula,which includes the sensitive identification factor F of the region,is obtained by reasonable approximation,and then the prestack inversion method based on the new AVO approximation is studied.At last,this sensitive factor F is used to identify the favorable reservoir from the prestack path set.Through the precision analysis,it is concluded that this method is feasible to use the anti performance sensitive lithology identification factor F to predict the initial reservoir in the range of error allowable.The prestack inversion method based on the sensitive lithology identification factor has taken into account the high noise resistance of the conventional elastic impedance inversion and the sensitivity of the lithologic identification factor to the reservoir,and the method of extracting the sensitive lithology identification factor F directly from prestack seismic data reduces the cumulative error of the indirect calculation band.It has good recognition effect in reservoir prediction of Qikou sag.