Comparative analysis on the impact of water saturation on the performance of in-situ combustion

The amount of oil together with the water Originally in Place (OIP), makes up the liquid phase in heavy oil reservoir systems. This amount of liquid present in the pores of the reservoir system, known as liquid saturation, plays a vital role in improving oil recovery through the In-Situ Combustion (ISC) process. The oil phase acts as a fuel in generating the thermal energy required for viscosity reduction and the water phase supports in the formation of an enlarged condensation zone that aids in the higher mobility of the low viscous oil. A numerical investigation is carried out to study the role of water saturation on the performance of in-situ combustion in a heavy oil reservoir. A finite-difference based numerical model is developed and validated for water recovery. The model is then used to carry out the impact of liquid saturation on the performance of the ISC, as it plays a vital role in screening criteria for the selection of ISC. The numerical results projected a significant effect on the thermal and production profile during the process. A comparison between the effect of variation in water and oil saturations projected a significant increase in reservoir temperatures with increased water saturation than the oil saturation. The highest reservoir temperatures are observed at the maximum liquid (oil and water together) saturation. Further, the additional water drive provided by increased water saturation is observed to contribute to early production rates.