Abstract
Understanding subsurface fluid flow behavior is essential for optimizing enhanced oil recovery (EOR) strategies in petroleum reservoirs. This study presents a comprehensive tracer-based diagnostic approach combining both aqueous- and gas-phase tracers to characterize pre-EOR water and gas movement in a synthetic reservoir model. Methanol, a conservative aqueous-phase tracer, and perfluoromethylcyclopentane (PMCP), an inert gas tracer, were employed in two separate simulations using the commercial software reservoir simulator. In the water-phase tracer study, methanol was injected to assess water flow dynamics. Tracer recovery ranged from 20% to 29% across four production wells, with water velocities between 0.35 and 0.41 m/d. Breakthrough times varied from 3092 to 4247 days, and mean residence times were estimated between 3900 and 4810 days. The calculated swept pore volume ranged from [Formula: see text] to [Formula: see text] [Formula: see text]. Production Well-2 showed the highest recovery and swept volume, indicating a stronger hydraulic connection with the injection well and making it a suitable candidate for targeted EOR operations. In the gas-phase tracer simulation, PMCP was injected into a gas injection well to evaluate gas flow behavior. Tracer concentration-time curves obtained from four production wells revealed that Production Well-1 exhibited the highest tracer recovery of 38% and the shortest breakthrough time of 796 days, signifying a direct flow path and strong connectivity. Conversely, other wells showed longer residence times up to 1736 days and lower recoveries between 19% and 21%, indicating more complex flow paths and lower sweep efficiency. Differences in swept pore volume among wells underscored the impact of reservoir heterogeneity on gas movement and distribution. The combined results demonstrate the utility of integrating conservative aqueous and inert gas tracers for detailed reservoir characterization. Such dual-phase tracer diagnostics enable identification of preferential flow paths, unswept zones, and inter-well connectivity, thereby facilitating more effective EOR planning and improved reservoir management.