Enhancing Condensate Production by 29%, Through Thermal Gas Injection from a Retrograde Gas Condensate Reservoir - With an Operational Case Study in the Western Desert of Egypt

Abstract In retrograde gas condensate reservoirs, the accumulation of liquid from natural gas below the dew-point pressure leads to condensate blockage, a significant issue in reservoir damage. Although most of this liquid doesn't reach the level required for production, it hinders the flow of natural gas, affecting its production. This study focuses on the impact of gas injection methods (like methane, carbon dioxide, and nitrogen) and high-temperature steam on an Egyptian retrograde gas condensate reservoir. Various scenarios were tested, involving different temperatures, enthalpy levels, types of injection gases (CO2, N2, CH4), and injection rates. The findings revealed that neither conventional nor thermal gas injection methods significantly increased cumulative gas production compared to simply depleting the reservoir. However, non-thermal gas injection methods boosted cumulative condensate production by 8.6%. Notably, thermal CO2 injection showed a substantial increase, enhancing condensate production by 28.9%. The study found that thermal gas injection does not vaporize condensate more effectively than conventional injection methods under similar reservoir pressure trends. Instead, the primary benefit of thermal injection is in enhancing condensate mobility. Therefore, thermal injection is most suitable for depleted retrograde reservoirs, where a significant amount of non-producible liquid has already accumulated. The research also explored the operational aspects of implementing thermal gas injection in retrograde gas condensate reservoirs. This includes considerations for carbon dioxide recovery units, compressors, storage tanks, corrosion-resistant pipelines and tubing strings, as well as corrosion inhibitors and downhole gas heaters.