Karst fractured-vuggy units are the main type of carbonate reservoirs and have strong heterogeneity;thus,it is difficult to accomplish quantitative prediction.Conventional seismic inversion methods are suitable for quantitative prediction of clastic res-ervoirs with weak heterogeneity.However,quantitative karst reservoir prediction with high precision is a much tougher problem.The idea of facies-controlled inversion is a plausible solution.By using discontinuity attributes,such as amplitude curvature,to iden-tify carbonate reservoirs qualitatively,a low-frequency model is established to constrain the inversion process.The inversion results can further improve the resolution of the fracture-cavern reservoirs.On this basis,a deterministic facies-controlled inversion meth-od based on gradient structure tensor is proposed.The method includes three steps.Firstly,based on the gradient structure tensor,reservoir facies and non-reservoir facies are divided to reflect the contour of the carbonate fractured-vuggy units.Secondly,a low-frequency model is established with seismic facies as the constraints.Finally,the low-frequency model is applied to the inversion process to obtain seismic attributes sensitive to reservoir properties and realize quantitative prediction of heterogeneous carbonate reservoirs.The results of model tests and a field application to Area M in the Tarim Basin show that the method is feasible for res-ervoir prediction with strong heterogeneity,as it pinpoints different types of carbonate reservoirs and predicts inter-cavity connec-tivity.Seismic prediction agrees with well drilling results and production performance.It lays the foundation for systematic quanti-tative study of carbonate reservoirs.
维普
万方数据
