STUDY ON THE MECHANISM OF DRAWDOWN MANAGEMENT OF SHALE GAS HORIZONTAL WELL CONSIDERING CREEP EFFECT

Considering the characteristics of shale reservoirs such as the low matrix permeability and complex natural fracture development, shale gas is mainly developed by multi-stage fracturing horizontal wells. The production of shale gas wells adopts the two modes: pressure relief production and pressure control production. Currently, scholars generally believe that pressure control production can improve the EUR of shale gas wells, and stress sensitivity is the main reason why the effect of pressure relief production is worse than that of the pressure control production. In this study, besides the stress sensitivity of matrix and fracture, the creep effect of matrix is also considered, and embedded discrete fracture models under the influence of creep are established. The results show that pressure relief production is better than pressure control production when only stress sensitivity is considered, and pressure control production is better than pressure relief production only when creep effect is considered. In addition, inhibiting the creep effect of shale is one of the mechanisms of improving the EUR of shale gas wells through pressure control production. With the increase of pressure control time, the gas well EUR shows a trend of increasing first and then decreasing, and there is an optimal value for pressure control production; The larger the matrix creep parameter, the higher the conductivity of the artificial fracture, the smaller the matrix permeability, the smaller the adsorption volume, and the better the effect of pressure control on gas production This study explains the production increase mechanism through pressure control production, laying a foundation for the optimization of shale gas well production system.