Numerical Simulation Study on Gravel Packing Parameters of Horizontal Wells in Natural Gas Hydrate Reservoirs

To address the high risk associated with gravel packing operations in horizontal wells located in shallow soft formations of natural gas hydrates in the sea, and the challenges in optimizing process parameters, we developed a numerical model using the CFD-DEM coupling method. This model takes into account the inter-particle and particle-wall interactions of ceramic particles, as well as the transport and settlement laws of the proppant particles in the screen and casing ring. By simulating and visually calculating the macroscopic flow pattern changes of the sand-carrying fluid under different process parameters, we were able to gain insights into the gravel packing process in horizontal wells. The simulation results indicate that in the long horizontal section gravel packing process of shallow soft hydrate reservoirs, using lightweight ceramsite for construction is safer. As the density of ceramsite increases from 1.07 g/cm3 to 1.80 g/cm3, the gravel packing rate decreases from 93.36% to 90.73%. Increasing the viscosity of the sand-carrying liquid is beneficial for gravel packing construction. With an increase in viscosity from 5 mPa·s to 10 mPa·s, the gravel packing rate rises from 93.36% to 94.38%. Controlling the gravel concentration appropriately promotes denser packing. As the gravel concentration increases from 10% to 20%, the gravel packing rate decreases from 93.36% to 90.44%. Pumping at a high displacement is advantageous for improving the packing rate. When the displacement of the sand-carrying liquid decreases from 1.0 m3/min to 0.6 m3/min, the packing rate decreases from 93.36% to 91.09%. The packing effectiveness is most significantly affected by liquid filtration loss. When the filtration loss rate reduces from 30% to 10%, the packing rate decreases from 93.36% to 89.71%.