CO2 Huff-n-Puff Process in a Light Oil Shallow Shelf Carbonate Reservoir

Abstract

The principal objective of the Sundown Slaughter Unit (SSU) CO2 Huff- n- Puff (H- n- P) project is to determine the feasibility and practicality of the technology in a waterflooded shallow shelf carbonate environment. Sundown Slaughter Unit is the second demonstration site associated with this project, following the unsuccessful test at Central Vacuum Unit. The ultimate goal will be to develop guidelines based on commonly available data that other operators in the industry can use to investigate the applicability of the process within other fields. The technology transfer objective of the project is to disseminate the knowledge gained through an innovative plan in support of the Department of Energy's (DOE) objective of increasing domestic oil production and deferring the abandonment of shallow shelf carbonate (SSC) reservoirs. Tasks associated with this objective are carried out in what is a timely effort for near- term goals. The goal of this Sundown Slaughter Unit Project is to demonstrate the CO2 Huff- n- Puff process in a waterflooded, light oil, shallow shelf carbonate reservoir within the Permian Basin. The CO2 Huff- n- Puff process is a proven enhanced oil recovery technology for Louisiana- Texas gulf coast sandstone reservoirs. The reader is referred to three Society of Petroleum Engineer (SPE) papers, No. 15502, No. 16720 & No. 20208 for a review of the theory, mechanics of the process, and several case histories. The process has even been shown to be moderately effective in conjunction with steam on heavy California crude oils. Although the technology is proven in gulf coast sandstones, it continues to be a very underutilized enhanced recovery option for carbonates. The goal of this technology demonstration is to gain an overall understanding of the reservoir qualities that influence CO2 Huff- n- Puff production responses within a heterogeneous reservoir such as the shallow shelf carbonate environment of the Sundown Slaughter Unit. A generalized reservoir model was developed and used to determine the importance of various geological and operational influences upon the CO2 Huff- n- Puff process at CVU. The findings at CVU would be applied to the demonstration site at SSU without further simulation studies being conducted at SSU.