Optimizing the Benefits of Conversion of Depleted Oil Reservoirs for Underground Natural Gas Storage in Nigeria

Abstract

Underground natural gas storage in depleted oil reservoir was examined with reservoir Z-16T located onshore in Nigeria. The geological information and the production history of the reservoir were gathered, which aided in the computation of the storage capacity at a given pressure as well as at various pressures. The plot of well flowing pressure, Pwf against flow rate, Q shows the deliverability of the reservoir at various pressures. The study which its objectives are to check the suitability of reservoir Z-16T for underground gas storage and to determine the benefits of operating the reservoir as a storage system, shows that the reservoir is ideal for the purpose. The benefits which were derived from the process of operating the storage system include: (1) utilization of the abandoned oil wells of known production histories; (2) recovery of substantial quantities of oil that otherwise might not have been recovered; (3) converting partially depleted oil reservoirs to total depletion types; (4) secondary recovery practice through continuous gas repressuring and repeated gas cycling; (5) producing vaporized oil as natural gas liquids or condensates; (6) preventing the huge wastage of gas through flaring; (7) stopping the greenhouse emission and attracted penalty; (8) utilising already existing facilities

Keywords: Natural gas, depleted reservoir, storage, deliverability, leakage, injection, pressure, benefits, secondary recovery, gas flaring