Enhanced oil recovery simulation study for Citronelle field, Alabama

The world is on the verge of an energy crisis due to rising demand for fossil fuel to meet both domestic and industrial energy requirements. In order to meet this rising fossil fuel need, it is important that enhanced oil recovery (EOR) schemes, which are more efficient hydrocarbon recovery techniques than primary and secondary recovery methods, are used to recover conventional oil reserves from already discovered fields. Continuous CO2 and the Water Alternating Gas (WAG) injection schemes are two basic EOR techniques for gasflooding reservoirs. The primary objective of this research project focuses on enhancing oil recovery from a very small pilot area of Citronelle oil field using CO2 miscible flooding. The miscible flood performance of carefully targeted CO2 injection was modeled using a fine-scale open source compositional simulator nSpyres. The simulation runs were performed using regular grids with a total of 8.2 million cells. The CO2 injection pilot did not result in any new recovery. However, it helped identify many crucial characteristics for consideration in a comprehensive CO2 project for entire Citronelle field, such as non-workability of WAG scheme due to loss of injectivity after converting back to water injection, presence of natural and induced fractures that affects flood performance, as well as operational issues - down-hole pumps, well integrity, and difficulties with data collection due to the mixing of "power oil" with produced oil - which will need thorough consideration.