Publications

Pure CO2 was injected to a depleted gas reservoir to increase gas recovery. The objective of this paper is to introduce a simple method from commercial simulator about the mechanism of CO2 injection to Enhance Gas Recovery (EGR) in depleted gas reservoir. This implementation can also decrease CO2 emissions to the atmosphere. It will usefull to prevent the incremental of green house gases due to oil and gas exploration activities.Five cases have been simulated, the first was comparing CH4 production using CO2 injection and without injection, the second was to inject CO2 at different perforation depth, the third was to inject CO2 at different reservoir condition, the fourth was to inject CO2 with several injection rate, and the fifth was to change bottom hole pressure at the production well. In this paper diffusion effect is neglected, the mixing of CO2 and CH4 will only depend on some features such as density, mobility ratio and solubility in water formation. In all cases, the project will be terminated when the concentration of CO2 in the produced gas stream reach 20% (breakthrough). Two injection of CO2 cases have been simulated for the five cases, the first was to inject CO2 at the beginning of gas production for pressure maintenance, and the second was to inject CO2 after years of production when the gas production rate started to decline.Higher methane recovery was achieved when injection of CO2 began when the gas production rate started to decline. At this case, 99,7% methane recovery was achieved at BHP was adjusted to 500 psi. Higher CO2 injection rate and lower production well bottom hole pressure, the breakthrough condition of CO2 become faster. The fastest breakthrough (64 days) was achieved when the CO2 injection rate flown at 1,000,000 ft3/day and production well BHP was 500 Psi. If CO2 injection rate became lower and production well BHP became higher, the production mass rate of methane became lower too. Methane production mass rate is tremendously higher when the perforation of injection well took at above of GWC. The sequestration of CO2 is effective at higher production well BHP and high CO2 injection rate to load more CO2 into depleted reservoir. Highest recovery rate that achieved at breakthrough time was performed when injector perforation took at aquifer zone which the production bottom hole pressure was 500 psi and CO2 injection rate was 100,000 ft3/day.