3D discrete network modeling of shale bedding fractures based on lithofacies characterization

Abstract

Taking the Upper Ordovician Wufeng-Lower Silurian Longmaxi shale gas field in the Jiaoshiba area in Sichuan Basin as an example, 3D discrete network modeling of shale bedding fractures based on lithofaices characterization was studied. The development of shale bedding fractures are controlled by shale lithofacies and shale bedding fractures in different lithofacies vary widely in development intensity, so this study developed a new methodology of 3D discrete network modeling of shale bedding fractures based on lithofaices characterization. This methodology constructs modes of shale lithofaices and shale bedding fractures by analyzing shale reservoir lithofacies and describing shale bedding fractures; builds shale bedding fracture index 3D model relying on 3D shale lithofaices model; builds development intensity 3D model of shale bedding fracture limited by 3D shale lithofaices model; and finally, builds 3D discrete network model. This methodology has been used to construct the 3D discrete network model of shale bedding fractures of Wufeng-Longmaxi shale reservoirs in Jiaoshiba area. The modeling results visualized the distribution, development scale of shale bedding fractures in main production layers in the study area and showed the variation of dip angle and azimuthal angle of each shale bedding fracture in the three-dimensional space, providing basic geological parameters for production simulation of the shale gas field later. Key words: shale lithofaices, shale bedding fracture, development index, development intensity, 3D discrete network model, Sichuan Basin, Upper Ordovician Wufeng Formation, Lower Silurian Longmaxi Formation