Effects of Solubility Modeling on Fluid Flow in Natural Gas Fields with Presence of Aquifers

Summary This study investigates the effects of gas solubility on reservoir performance in multi-layered gas-water systems, focusing on two distinct models: one incorporating gas dissolution in the aqueous phase and the other treating water as an immiscible phase. Using a fully implicit, compositional reservoir simulator, the models analyze gas production rates, reservoir pressure maintenance, and recovery factors. The solubility model, where gas dissolves in water, demonstrated higher sustained production rates, improved pressure maintenance, and enhanced overall recovery compared to the immiscible model. This is attributed to gas dissolution acting as a pressure buffer, allowing gas to be released more gradually over time, thereby supporting a prolonged production period and reducing rapid depletion. The non-soluble model exhibited faster pressure drops and reduced gas recovery. Additionally, the study highlights the increased computational complexity introduced by the solubility model, although efficient convergence was achieved. The findings show the importance of incorporating gas solubility in reservoir modeling to optimize gas recovery strategies, particularly in high-pressure, water-bearing reservoirs, and support future applications of solubility-based approaches in multi-phase flow simulation.