Numerical simulation on oil rim impact on underground gas storage injection and production

A large number of underground gas storage operating experience shows: the oil rim has a great impact on gas injection and production. Here, the underground gas storage in the Dagang Oilfield (G393) was taken as an example to study the oil rim impact mechanism. Firstly, the G393 gas reservoir developmental history was simulated, based thereon, the equations governing the distribution of gas, oil, and water in the reservoir before building the storage injection and production equipment was established. Then, the oil rim impact mechanism on the gas seepage of underground gas storage operation was studied using numerical simulation method and the factors affecting oil recovery from the oil rim for the gas diffusion were outlined. The result shows that oil rim may prevent seepage of gas, resulting in a one-way gas onrush, thus affecting the smooth operation of underground gas storage. In addition, crude oil recovery in the oil rim may affect the gas well's production capacity, the lower the degree of recovery of crude oil, the harder for the underground gas storage to run quickly and smoothly. Finally, the most appropriate injection wells for the G393 fault-block gas storage were designed, by which process the oil production period was shortened to 8 years, ensuring stable and efficient operation of the underground gas storage.