Abstract

Thermal oil recovery m ethods could be an effective s olution to many crucial problems not only in hea vy/light oil reservoirs, but also in light oil reservoir. Steam flooding has proved it’s efficiency to change the reservoir and fluid properties in light oil reservoirs leading to higher oil displacement and sweep efficiency. The reservoir under study is the main pay/upper sandstone member in South Rumaila oil field located in Iraq. It is a mature oil field with around 58 years of production with 40 producing wells. The reservoir has an infinite acting aquifer located at the east and west flanks. The strength of this aquifer from the west flank is much larger than it’s in the east flank because the formation permeability at the eastern flank is less th an as at th e western one; therefore, 20 injection wells have been drilled at the east flank to maintain the aquifer water approaching to the reservoir. The formation depth is 10350 ft. sub-sea with a maximum vertical oil column of 350 ft. The average bubble point pressure of 2660 psi and the ave rage reservoir temperature is 210°F while oil density is 34°API. In this study, A comparative simulation study (Black oil and thermodynamic) has been done to investigate steam flooding feasibility improve oil recovery in comparison to two base cases of with and without water injection.

Two reservoir simulators, black oil (CMG-IMEX) & thermodynamic (CMG-STARS) have been applied to demonstrate the impact of steam flooding as heating agent to enhance the sweep efficiency through this heterogeneous reservoir. The steam injection has been done considering the current twenty injection wells with 10,000 stb/day per well. The results showed the co-impact of steam injection with simultaneously enhanced water drive from the aquifer to sweep the oil towards the reservoir crest. The cumulative oil production for steam flooding scenario has been compared with the outcome of the two base cases with and without water injection and demonstrated a significant incremental of oil recovery. The cumulative oil production for the two base cases at the final time step of 1 Feb. 2022 is equal to it's amount by steam flooding on 1 Oct. 2015.

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