Reservoir Sandbody Prediction Combined Pre-stack With Post-stack Inversion Methods In The Saertu Layer Of The Northern Part Of Daqing Oilfield

In the exploration and development of oil and gas resolution is one of the important seismic inversion factors.It greatly affects the quality of reservoir classification in the study area because of the limitation of the seismic bandwidth.The inversion results are needed to establish the range of sandbody in horizontal direction,but also divide the layers to predict sandybody in vertical direction with enough resolution.Therefore,how to improve the seismic resolution in practical application becomes so significant.The pre-stack seismic inversion result can effectively reflect the underground reservoir lithology and fluid nature,but can not identify the thin interbedded reservoir because of the limitation of the seismic resolution.The post-stack seismic inversion can better use the information like gamma,resistivity and density parameters on distinguishing sandstone and mudstone in vertical direction.However,it can not accurately predict the distribution of sand body in horizontal direction with uncertainty and multiple solutions.So it needs the use of post-stack geostatistical statistics inversion to improve the resolution of the inversion based on the result of the pre-stack elasticity inversion.Firstly,S1 and S2 thin layer of Saertu oil layer in the northern part of Daqing Oilfield was considered as the intended interval,using the known data of compressional wave velocity,density,porosity and shale content combined with the Xu-White method and logging constrained inversion,the shear-wave logging curve is constructied in a situation without shear-wave slowness curve in study area.Also it can provide the reliable data of shear-wave velocity for the petrophysical analysis.Next,geostatistical framework model is built with logging elasticity parameters like the P-Impedance,S-Impedance,density and the poisson's ratio as a constraint in vertical direction.Another geostatistical framework model is built with the result of the pre-stack elasticity inversion as the result of the pre-stack elasticity inversion as a constraint in horizontal direction.Then,it combines pre-stack seismic inversion with post-stack seismic inversion by ensuring the lateral resolution of the inversion results and improving the vertical resolution.At last the inversion result shows that sandbody prediction can be better combined with the seismic attributions because of the increase of seismic resolution and the distribution of sedimentary microfacies also can be established in the study area.