Taking the fractured gas constant volume body as the research unit, considering the boundary conditions such as the height of the constant volume body, the cross-sectional area of the constant volume body, the initial formation pressure, the initial bottom hole pressure and the initial overflow, a mathematical model of the average pressure of the fractured formation of the constant volume body varying with the overflow time is proposed; With the help of programming language, the model is solved. Taking well ST1 as an example, the results show that with the increase of fracture dip angle, the fracture width increases and the fracture permeability also increases; The permeability of fractured gas reservoir is most affected by matrix stress, followed by dip angle and fracture spacing. With the constant volume overflow, the overflow flow decreases rapidly in the initial stage, and then remains stable for a long time until it decreases again in the end; With the increase of throttle back pressure and gas influx, the annular gas holdup increases. The mathematical model of average pressure of fractured formation with constant volume can calculate the change value of average pressure with time, and can guide the design of kill fluid density and the loading of backpressure target value in the process of circulating exhaust.

以压裂气体定容体为研究单位，考虑定容体高度、定容体截面积、初始地层压力、初始井底压力和初始地层压力等边界条件。溢流，提出了等容体裂缝地层平均压力随溢流时间变化的数学模型；在编程语言的帮助下，模型得到了求解。以ST1井为例，结果表明随着裂缝倾角的增大，裂缝宽度增大，裂缝渗透率也增大；裂缝性气藏渗透率受基质应力影响最大，其次是倾角和裂缝间距。随着定容溢流，溢流流量在初期迅速减少，然后长期保持稳定，直到最后再次减少。随着节气门背压和气体流入量的增加，环形含气量增加。等容裂缝地层平均压力数学模型可以计算出平均压力随时间的变化值，可以指导压井液密度的设计和循环排气过程中背压目标值的加载。