عنوان مقاله [English]
Sand production, which is a critical phenomenon in the oil and gas well walls, is numerically investigated in this research. The main goal is to study the particulate mechanism of sand production in unbonded assemblies and examine the effects of stress level and pressure drawdown on the model. Discrete Element Method (DEM) in combination with the Lattice-Boltzmann Method (LBM) is selected to simulate the fluid flow through porous media. The Immersed Moving Boundary method is used to couple the DEM and LBM methods. After developing a computer program, a 2D model of sand production is simulated under radial flow. The simulation results show that as the confining stress increases, the number of produced particles and sand production rate increases. After the initiation of sand production, the sanding rate decreases in all models due to the formation of sand arches around the central hole. These sand arches are weak and usually unstable, and after the collapse of every arch, the new arch is formed and replaces the previous one with a larger diameter. The results also show that the pressure drawdown has a negligible effect on sand production at low stress levels. However, at high stress levels, the increase of pressure drawdown significantly increases the number of produced particles (a 50% increase in pressure led to more than twice produced particles). It is also found that the 2D coupled DEM-LBM is a promising tool to predict the mechanism that governs sand production and its main influencing factors.