Evaluation of the First Cycle of Steam Stimulation in North Kuwait Heavy Oil Thermal Pilots

摘要

There are two ongoing steamflood pilots with inverted five-spot, 5-acre and 10-acre spacing patterns in North Kuwait heavy oil field. KOC determined that performing two or three Cycle Steam Stimulation (CSS) cycles followed by steamflood is required to achieve the production target from a multi-layer reservoir with two vertically separated heavy oil zones. A previous reservoir simulation study identified two possible completion strategies. One completion strategy for simultaneous steaming in the 5-acre spacing pattern and the other completion strategy for steaming one zone at a time in the 10-acre well spacing pattern. In this paper, we discuss for the two pilots, operational and monitoring challenges and the substantial difference in the performance after first CSS cycle for the two well completion strategies. The Steamflood pilots are currently at the pre-flood stage and the first cycle of the Cyclic Steam Stimulation (CSS) has been finalized. A comprehensive reservoir and well surveillance program is being conducted to monitor and gather data necessary to better understand the reservoir and well performance in the pilots. One of the goals of the pilots is to use the acquired reservoir understanding to determine a completion strategy for commercial development of the field from two options identified in the reservoir simulation study. This paper presents insights on the difference in the performance with the two well completion strategies. The first CSS cycle in the wells with 10-acre spacing and the completion strategy for steaming one zone at a time demonstrated relatively better performance compared to the wells in the 5-acre pilot with a completion strategy for simultaneous steaming where more challenges were observed. The reservoir properties and field surveillance data were used to explain this performance difference for the two well completion strategies after first cycle of CSS. The recommendations and conclusions in this paper are based on actual field data in a multi-layered heavy oil reservoir after the first CSS cycle. Future papers will present the results after further CSS cycles and steam flooding.