A new applicable safety factor index (SFI) was developed to identify the impact of mechanical stresses and hydrodynamic forces on the potential sanding of a sandstone reservoir. The SFI is calculated by a fully numerically coupled analysis of the mechanical deformation and hydrocarbon fluid flow in the sandstone formation via FLAC3D software, Itasca Consulting Group, Minneapolis, USA. Sand production is commonly ascribed to mechanical failure while the influence of hydrodynamic forces on sandstone erosion is neglected or underestimated. However, the new SFI enables the designer to quantify the impact of mechanical and hydrodynamic forces separately on the future occurrence of sanding. Quantitative comparison is a beneficial tool to choose the most appropriate layout of the wellbore and perforations. The results demonstrated that hydrodynamic forces may have a more significant effect on sand production than mechanical stresses. Furthermore, the sanding process does not necessarily commence at the wellbore wall and may occur at any spot around the perforations with the highest stress state. The calculated SFI was effectively utilized to reduce the sand production, an intensely problematic issue in the oil field used here as a case study. The new SFI can be deployed to design the optimum wellbore and perforation configuration to decrease the sanding potential in a sandstone formation.