Research and test for shut-in after fracturing of volume fracturing technology in Sulige low pressure tight gas

Shut-in after fracturing has become an important supporting technology for volume fracturing in unconventional oil and gas wells, which is helpful for gas and water imbibition replacement to increase single well production. In this paper, the hydraulic pressure, capillary pressure and osmotic pressure, the three main forces that affect well production, are calculated and compared in the Sulige tight sandstone gas field and Fuling shale gas field. The results show that the total forces affecting well production in the Sulige gas field are similar to those in the Fuling shale gas field, and it has the potential to exhibit shut-in after fracturing. For the characteristics of “low pressure” and “water blocking risk” in Sulige gas field, it is suggested that:(1)injecting N2 or CO2 during hydraulic fracturing and reasonably controlling the shut-in time after fracturing, such as shut-in for approximately 30 h, can ensure effective natural fluid flowback while replenishing energy to the formation and reduce the damage caused by water blocking and (2)the waterproof lock slickwater is used in the test wells, and the result shows that slickwater can reduce the reservoir damage and increase well production when compared with guanidine gum fracturing fluid. This research can provide some basis and reference for the field test of shut-in after fracturing in the Sulige tight sandstone gas field.