Techno-Economic Feasibility of Ethane Based Enhanced Oil Recovery in Nigeria (CASE Study: Niger Delta)

Abstract

Increasing oil recovery has been one of the issues enlisted for attention in oil producing countries around the world for past decades. So many forms of oil recovery techniques have been considered; infill drilling of new wells, production and injection control, pressure control, water flooding and other methods of Enhanced Oil Recovery (EOR), most of which have been implemented in other parts of the world. Nigeria as an oil producing country has not taken interest in EOR techniques solely because of the abundant occurrence of its conventional oil. Even though infill drilling and water flooding have been implemented to increase the productivity on some producing fields, a more viable and profitable method of EOR that can curb waste and reduce pollution should be applied in the field. This study therefore aims at examining the technical and economic feasibility of Ethane-based EOR in Nigeria. This is a hydrocarbon gas injection process where ethane is injected into the reservoir to improve the oil recovery. A Niger Delta field was characterized and the model is used to simulate ethane gas injection. Of all the different injection cases simulated ranging from water injection, ethane gas injection and ethane water-alternating gas (WAG) injection, the ethane WAG injection simulation shows more incremental recovery as the injected water sweeps out the oil bypassed by the gas. Since ethane can be extracted from the natural gas routinely flared in Nigeria, economics of the study shows that having a natural gas processing plant for the extraction of ethane gas to be injected is more economically attractive than procuring the gas from external sources. This study shows that operation of ethane WAG for 25 years yields 14 years of payback of capital investment with substantial revenue generated in subsequent years from oil production.