Fracture Dynamic Propagation Model of High-Energy Gas Fracturing for Casing Perforated Well

Abstract

The onshore oil and natural gas industries of China have started a large-scale development when crude oil reserves have been difficult to recover. The stratum fracture modification is an indispensable measure to efficiently develop oil and gas fields. Hydraulic fracturing is the most important reservoir stimulation technique, but it is still faced with various problems such as the failure to fracture the target reservoir, long fracturing duration, and short efficient length of the fracture. High Energy Gas Fracturing (HEGF) can easily break down the high-fracture-pressure oil reservoir and generate multiple fractures free of in-situ stress. Moreover, HEGF entails no large-scale devices, and this method is strongly adaptable to the environment without causing environmental pollution. After combining the two technologies (HEGF and the other), then they can complement each other with their strengths. That is, both of them decrease the fracture initiation pressure of (or caused by) hydraulic fracturing on the one hand, and to extend, gather, and support multiple radial fractures of gas fracturing on the other hand. Thus, a fracture zone with a large radius is finally formed, and the percolating resistance of the fluid is significantly decreased.Moreover, in this study, a dynamic model related to the drainage flow of the perforated holes in a gas well, fluid pressure distribution in the fracture, fluid seepage on the fracture wall, fracture initiation criterion, and fracture propagation velocity during the HEGF process has been presented. Consequently, a gas/liquid/solid coupling fracture dynamic propagation model during the HEGF process can be built to provide a theoretical basis for the accurate simulation of the fracture form changes during this process.