Connectivity evaluation for three‐dimensional fracture network in support‐based model: A case study in the Ordos Basin, China

Abstract

Abstract Connectivity is an effective indicator to describe the flow paths and mechanical behavior of reservoir fractured rock masses. The connectivity evaluation of fracture networks plays an important role in the design, assessment, and development of reservoirs in several important engineering applications, such as geothermal recovery and petroleum industry. Based on Allard's definition of a connectivity index, a 3D connectivity evaluation method is proposed in this study by building the connectivity functions of the supports. Meanwhile, different connectivity functions are built for different situations. In addition, a convex polygon is used to simulate the fracture to make the fracture network as real as possible. The accuracy of the generated fracture network was verified by comparing three parameters of fracture, and the results showed that the relative error was less than 5%. Some examples in the Ordos Basin, China, are given to verify the correctness of the program and method. Analysis results show that the 3D method is more realistic than the 2D connectivity evaluation, and the connectivity field of the fracture network is more reliable in the 3D method. Moreover, the proposed method can show the potential preferential flow path in a stereoscopic manner and thus greatly extends the function of connectivity analysis. This method provides important information for the prediction of paths and the evaluation of the connectivity of the fracture network and is important in evaluating the optimal location of geothermal recovery and petroleum industry.

Keywords

• connectivity
• connectivity evaluation
• connectivity functions
• connectivity index
• fracture networks