Coupling simulation of multistage pulse conflagration compression fracturing

Abstract

Due to the transient and multi-field coupling complexity of the multistage pulse conflagration compression fracturing, the coupling solution method for it was established, and the simulation calculation and field application analysis was conducted. The whole process of conflagration compression fracturing was divided into five subsystems: propellants conflagration loading, piezoresistive liquid column movement, perforation discharge, fracture initiation and dynamic extension. Based on the given assumptions, the kinetic model of each subsystem was built, and the coupling solution method of multistage pulse deflagration compression fracturing process was obtained using the node system analysis method. With the coupling solution method, a reasonable range of propellants charge can be calculated and the dynamic prediction of the conflagration pressure and fracture shape can be realized. Through simulation calculation, the changes of propellants conflagration pressure, piezoresistive gas-liquid interface displacement and fracture length were analyzed, and the whole process was divided into five phases by the time. The field application results indicate that the multistage pulse conflagration compression fracturing conducted based on the coupling solution method can fracture the reservoir successfully and reduce the breakdown pressure, making sure that the follow-up measures are carried out smoothly. Key words: multistage pulse conflagration compression fracturing, high energy gas fracturing, breakdown pressure, fracture, dynamic model