Oil production may be accompanied by Sand Production (SP) in the weak sandstone reservoirs. Fluid flow is an important factor in transporting the separated grains and completing the SP mechanism. In this paper, the effect of fluid parameters, fluid flow, and fluid pressure on the SP is investigated by applying the Discrete element method (DEM). Parametric studies show that fluid velocity is reduced by increasing the fluid viscosity, leading to a drop in the SP. In the present study, for an accurate investigation and discovering the effects of viscosity and drag force, the boundary conditions were applied to retain the fluid velocity as a constant amount. The results showed that viscosity is directly related to SP. Moreover, we found that when the fluid velocity is high, there would be the possibility of catastrophic production in the reservoirs with a heavy oil fluid. The rock reservoir around the well will be loosened as soon as SP is initiated. The results also indicate that SP has a direct relation with fluid pressure, fluid velocity, and confining pressure.