Effect of proppant settlement laws on the productivity of shale-gas horizontal wells after the fracturing

The productivity of shale gas wells is greatly in fluenced by proppant distribution and fracture morphology after the fracturing. To investigate the proppant settlement laws, the numerical reservoir model considering adsorption, desorption and pressure sensitivity of shale gas comprehensively was established. In this model, the method characterizing proppant settlement is developed.Then, parametric variables were compared and analyzed, e.g. perforation location, settlement degree, fracture conductivity, reservoir matrix permeability. The pressure distribution and productivity characteristics of shale gas reservoirs were studied in consideration of proppant settlement. And the main factors controlling the productivity of gas wells after proppant settlement were fi gured out. It is indicated that the productivity of gas wells is decreased greatly by proppant settlement. Considering the migration and settlement of proppant in the process of fracturing, perforation shall be carried out in the middle and lower parts of gas reservoirs. If the fracture conductivity of shale gas reservoirs is up to 4 μm²·cm, gas wells can be exploited effectively. The proppant of 40/70 mesh is selected for fracturing. It is recommended to create the main fractures preferentially. The productivity of gas wells is in fluenced more by proppant settlement as the matrix permeability is higher, so some measures shall be taken in high-permeability zones to prevent proppant settlement. This model takes into consideration the characteristics of proppant settlement, so it can be used as the important guide for the productivity prediction and on-site fracturing of shale gas wells.