Effects of Impurities on Carbon Dioxide Storage Processes

Successful engineered impure carbon dioxide storage in geological reservoirs integrates both the ability to identify an appropriate reservoir and forecast their long-term integrity. As many pilot-scale CCS projects are ongoing successfully, very little attention has been focus on what quality of carbon dioxide is required for a specific geological reservoir of interest to maximize storage mechanisms and security. In this research, I report my findings on (1) reservoir fluid characterization using an equation of state based programme, and (3) a fully compositional, three dimensional reservoir simulation model using ECLIPSE compositional simulator to investigate the feasibility of injecting carbon dioxide rich gases captured using Post, Pre or Oxy fuel combustion capture technologies on two important aspects of large scale geological storage of carbon dioxide: well injectivity and enhanced gas recovery in a depleted gas reservoir. The simulation results shows that, the effectiveness of enhanced gas recovery process using impure carbon dioxide depends on the degree of mixing stability and mobility ratio. Until 10 % carbon dioxide produced, Pure CO2 and Post CO2 produced 62.2 MSm3 of methane gas compared to 61.5 MSm3 for Pre CO2 and 60.9 MSm3 Oxy CO2 . The well injectivity until original pressure of reservoir was attained (346 bar) using Pure CO2 and Post CO2 were 36.5 BSm3 compared to 36.0 BSm3 for Pre CO2 and 35.7 BSm3 for Oxy CO2. The model predicts that Post CO2 appeared to be the most desirable, as separation cost would probably be cheaper than Pure CO2 since both have the same compositional changes at typical reservoir conditions. Nevertheless, Oxy CO2 is least desirable to Pre CO2 but they will be very suitable candidates for shallow reservoirs with very low pressure and temperature gradients. The procedure and findings developed in this research can be used as guidelines for designing and implementing any future large scale CCS project in a gas reservoir.