Production prediction method for pseudo steady period of fractured well in low-permeability Sulige Gas Field

At present, the computing model for dynamic prediction of fractured gas well production is mostly for steady state seepage or for unsteady state seepage of infinite formation, and rarely involved in production dynamic prediction method during pseudo steady flow period. For this reason, according to seeping process of gas in formations of fractured gas well, first based on the fact that, in pseudo steady flow period derived from mirror reflection principle controlled by boundary, there is a vertical fracture of finite conductivity capacity in the gas reservoir in the well, this paper presents a method for dynamic prediction of fractured gas well production in pseudo steady flow period based on a general expression of dimensionless pressure solution, and then gives the method for determining the time when pseudo steady flow begins to occur in rectangular bounded gas reservoir. The calculation results show that the fractured wells in Sulige low-permeability gas field are in boundary-controlled pseudo steady seepage period in two to four months after being put into production, and the conductivity capacity required by single wing fracture length of 150 m is about 30 D·cm. The method for dynamic prediction of production presented in this paper can also be used to optimize the hydraulic fracture parameters and fracturing size in other low permeability gas fields.