Optimization of construction parameters for deep coal rock fracturing based on response surface methodology

In order to comprehensively improve the fracturing effect of deep coal and rock gas, the optimization research of deep coal and rock fracturing construction parameters based on response surface method is carried out with the perforation section length, injection displacement and cluster spacing as the design parameters and the transformation rate of coal and rock reservoir as the target response. Taking the formation parameters of the research block as the engineering background, Abaqus software is used to establish a fine numerical model including coal reservoir and roof and floor. Through single-parameter simulation analysis, the optimal Design range of the single parameter was selected, and multiparameter simulation analysis based on Box-Behnken method was carried out by Design-Expert 13 software. The significance level of the influence of design parameters on the target response was analyzed by F-test method, and the response surface analysis under the interaction of each parameter was obtained. The results show that the response surface contour is elliptical, and the interaction between the three parameters of perforation section length, injection displacement and cluster spacing is obvious and significant. The parameters optimized by response surface method are as follows: perforation section length 3m, injection displacement 19m³ /min and cluster spacing 22m. When the optimized construction parameters are applied to the target well, the reservoir reconstruction rate and daily gas production of the well are higher than that of adjacent Wells.