Pressure Transient Simulation of a Single Horizontal Well with 3D Multifracture System: A Semi-Analytical Approach

Summary In recent years, multistage fractured horizontal well (MFHW) technology has been widely used in the development of unconventional oil and gas resources. Following the fracturing construction, complex fractures are generated around the wellbore. A proper understanding of the fracture characteristics can significantly influence fracturing evaluation and production estimation. To enhance this situation, we developed a semi-analytical model for the interpretation of fracture parameters and formation parameters in 3D space. First, we constructed the coupling between the three systems of reservoir, fracture, and well. Then, we proposed a methodology based on the connectivity matrix for identifying the longitudinal intersection of fractures and the corresponding grid division method. After that, we conducted model verification and sensitivity analysis. Finally, we classified the fracture networks into different types and carried out evaluations. The results indicate that the pressure derivative curve for 3D flow exhibits greater complexity compared with that of 2D flow. Fracture networks have the capacity to supply hydraulic fractures, and different types of fracture networks possess distinct characteristics on the pressure derivative curve. Furthermore, the disparity between vertical and horizontal permeability exerts a notable influence on vertical flow behavior. The pseudoradial flow in the vertical direction appears as a horizontal straightline segment on the pressure derivative curve, serving as an indicator that the fracture does not penetrate the entire formation. This work provides a theoretical basis for fracture evaluation and production prediction.