A Thorough Investigation of Newly Improved CO₂ Huff-and-Puff Injection for Storage and Enhancing Gas/Condensate Recovery.

Gas production is considered as an attractive alternative energy source to coal or oil to consolidate cleaner energy transition. CO₂-injection in gas condensate (GC) reservoirs can be beneficial both in terms of CO₂-storage, and GC-improved recovery. Several literatures reported conflicting findings on trends and level of CO₂-GC interactions, especially when an untuned equation of state (EOS) was used. These suggests a better understanding of CO₂-GC interactions. The benefits of a newly improved CO₂-Huff and Puff (HnP) injection method, compared to conventional-HnP method have recently been highlighted in our laboratory on high permeability core. This study investigates the combined multi-parameter-interactions effects between CO₂-GC fluid affecting their phase and flow behaviours in porous media. Coreflood simulations were first performed to history match the core flood experimental results whilst varying Corey-fitted relative permeability (kr) parameters, then larger reservoir scale was considered. The results indicated that using an EOS tuned to measured CO₂-GC PVT data improved GC-recovery by realistically capturing the CO₂/GC-interactions, and enhanced CO₂-injectivity. Also, adjusting the parameters of the Corey kr-model resulted in an improved CO₂/GC-match and the prediction processes. Overall, the new method ensured CO₂/GC- interactions at maximum condensate saturation with lower injected-CO₂, and resulted in improved GC-recovery, and higher CO₂-storage.