Study on the Variogram Analysis Methods of 3D Geological Modeling for Sandstone Reservoirs

Abstract

Variogram analysis is a necessary step for 3D stochastic modeling. Different variogram settings will directly affect the final distribution characteristics of model attributes. Setting the variogram parameters on the optimization results of sedimentary types of sub-units has become a key step in geological modeling. In this paper, the influence of variogram parameters on the simulation results of reservoir properties is studied to improve the analysis method of the variogram. This paper is for typical river-delta sedimentary reservoirs, specifically taking the SII7+8 layers as the research object. Multiple sedimentary microfacies types, including river, abandoned river, floodplain, natural dyke, coexist and show highly heterogeneous in the SII7+8 layers. On this basis, the reservoir is divided into 3 types of sand bodies and 11 kinds of sedimentary microfacies according to the effective thickness, sedimentary conditions, scale and shape of main sand bodies to study the distribution characteristics and extension scale of different sedimentary types in plane, so as to determine the variogram parameters of different sand body types, and accurately simulate the reservoir property distributions. The process in variogram analysis methods can further improving the accuracy of 3D geological modeling.