Application Of OVT Seismic Data Prestack Simultaneous Inversion

Gaoshiti subject to the north is an important area to replace Gaoshiti Dengying Formation exploration for its huge reserves.But the dolomite reservoir of Dengying Formation is a typical marine carbonate rocks reservoir.The reservoir of it is difficult to predicting for its strong heterogeneity,irregular shape distribution,various origin and complex reservoir.With the further deepening of the exploration degree in the area,the higher accuracy of the seismic inversion reservoir prediction is put forward.The poststack seismic inversion can only provide parameters such as the P-wave impedance of a single attribute,it is difficult to obtain the parameters of the geophysical characteristics of the reservoir,such as the aspect ratio,Poisson’s ratio.Obviously can not fully meet the requirements of the reservoir fine prediction.Pre-stack inversion reservoir prediction must be considered.And the quality of seismic data and logging data is directly related to the accuracy of pre-stack inversion prediction.In the pre-stack pre-stack reservoir prediction,the energy consistency of the pre-stack time-offset gather data is poor,the amplitude and AVO are poor,and the pre-stack inversion results are in good agreement with the well.In addition,some of the wells in the study area lack shear wave data,which must be subjected to shear wave prediction.How to improve the quality of pre-stack seismic data and the accuracy of shear wave prediction for prestack inversion is the main technical difficulty of reservoir prediction.In view of the technical difficulties of the fine prediction of the reservoir in the study area,the following research work is carried out:(1)The pre-stack simultaneous inversion method based on Fatti approximation can directly obtain the data of longitudinal wave impedance,shear wave impedance,density and so on.The reservoir lithology identification is more accurate and accurate,so this paper mainly uses the prestack longitudinal wave and simultaneous inversion of reservoir prediction technology to fine predict the reservoir.(2)After the OVT field migration of the prestack gathers in the study area,the gathers are more consistent with the conventional pre-stack offset gathers,the forward results and the wells are more matched,and the amplitude attributes of the gathers are better preserved And travel information,which is more favorable for prestack seismic inversion reservoir prediction.(3)Based on the particularity of reservoir lithology,fine rock physical modeling is carried out,and the Greenberg-Castagna empirical formula method and Gassmann fluid replacement technique are used to predict the shear wave in the study area.The results show that the comparison between the measured shear wave and the prediction curve through the partial well shows that the error of the prediction result is small,and the intersection wave velocity ratio can be used to distinguish the lithology.Through the pre-stack simultaneous inversion can quickly obtain the longitudinal and transverse velocity ratio,and then refer to the intersection plate to predict the thickness and plane distribution of the reservoir.The results of inversion data of prestack seismic data of OVT domain are higher than those of conventional prestack seismic data,and the reservoir prediction is more accurate and accurate.It can effectively guide the deployment of well location and improve the success rate of drilling.