The Variation Law of Fracture Conductivity of Shale Gas Reservoir Fracturing–Flowback Integration

Hydraulic fracturing is a commonly used technical tool in the extraction process of unconventional shale gas reservoirs. However, the damage caused by fracturing fluids to the proppant fracture inflow conductivity during the whole fracturing, reentry, and production process is very obvious, which affects the fracturing and production increase effect. Conventional proppant fracture inflow conductivity test experiments only use a single-phase fluid in the gas or liquid phase to complete the test and evaluation, and few scholars have paid attention to the change rule of inflow conductivity during the whole fracturing and re-discharge process. Therefore, combined with the characteristics of shale gas production, we simulated the whole fracturing–returning–production process, carried out three consecutive phases of proppant fracture inflow conductivity test experiments, and investigated the change rule of fracture inflow conductivity during the whole process. The results show that under the condition of closure pressure 35 MPa, after distilled water simulated fracturing, the damage to mineral sand flow-conducting capacity is as high as 81.55% due to the effect of shale hydration. During the simulated return discharge process, the gas-measured flow-conducting capacity experiments were carried out at 25%, 50%, 75%, and 100% of the initial gas-measured discharge, and the fracture flow conductivity kept rising, and its maximum recovery value was 54.67% of the original one; the experiments simulated the fluctuations caused by changes in the wellbore flow pressure on the closure pressure in the process of production as well as the influence of fracture flow-conducting capacity under the condition of long-term soaking of the proppant, and the results of this study are useful for the design of fracturing programs and high-efficiency fracturing of shale gas. The results of this study have certain reference significance for the design and efficient development of shale gas reservoir fracturing programs.