Application of Toe-to-Heel Air Injection (THAI) Process in Fractured Carbonate Systems: 3D Simulation of the Effect of Fractures Geometrical Properties, Reservoir and Operational Parameters

Abstract

Abstract Toe-to-Heel Air Injection (THAI) Technology, a new heavy oil recovery process to overcome Conventional Fire Flooding (CFF) defects, has been studied on non-fractured sandstone models and is found a promising Enhanced Oil Recovery (EOR) method for certain heavy oil reservoirs, but its applicability on fractured carbonate heavy oil reservoirs, such as those in Middle East, remained questionable. The objective of this paper was to evaluate the effect of fractures geometrical parameters such as fracture density, orientation and networking on the THAI process performance for a low permeable naturally fractured carbonate heavy oil reservoir in Persian Gulf coast namely "Kuh-E-Mond". To approach the problem, a combustion tube test using field crude oil and crushed carbonated rock performed and numerical model developed and validated according to the experimental results. Validated model modified to 3D to investigate the performance of THAI. THAI performance was studied in conventional and fractured models consisting fractures in Between Wells Region (BWR), Horizontal Well Region (HWR), vertical, horizontal and networked fractures. Ultimate oil recovery and recovery rate decreased in all fractured models as compared to the conventional case. Higher traversal fractures density reduced ultimate oil recovery. Near injector traversal fractures have less disastrous effect on the process performance. In the case of networked fractures (presence of both longitudinal and traversal fractures), accompany of longitudinal fractures enhanced the recovery achievable in the case of traversal fractures. Simulation results showed that THAI is more applicable on highly networked fractured reservoirs such as those occur in Middle East compare to lower density fractured reservoirs