Numerical modeling of CO2 injection scenarios in petroleum reservoirs: Application to CO2 sequestration and EOR

• Different scenarios for CO2 injection have been studied.
• The role of injection rate in the performance of CO2 injection have been studied.
• The role of miscibility condition in the performance of CO2 injection have been studied.

CO2 injection is a most promising method for enhancing oil recovery from petroleum reservoirs especially from depleted one. CO2 injection can be employed as secondary and tertiary enhanced oil recovery (EOR) methods. The most prominent advantage of CO2 injection is reducing greenhouse gases in the atmosphere and consequently reducing environmental problems. Different approaches have been employed to study the performance of CO2 in increasing oil production including miscible/immiscible injection, carbonated water injection (CWI) and CO2 injection into aquifer. In these methods different parameters can effect such as minimum miscible pressure (MMP), injection rate and so forth. Therefore, the main goal of this paper is to study of different CO2 injection methods and the effect of operational factors on the performance of each method by a numerical simulation model. In this study, a synthetic reservoir is considered for numerical simulation of CO2 injection process. To assess this goal, three different CO2 injection strategies including CO2 injection into the bottom aquifer, CO2 injection into oil column (pay-zone) and simultaneous CO2 injection into aquifer and pay-zone are defined. Based on the results obtained from three aforementioned injection scenarios, simultaneous CO2 injection into aquifer and pay-zone leads to higher oil recovery factor in comparison with other scenarios. Critical injection rate for each scenario was determined and employed in the case of simultaneous CO2 injection into aquifer and pay-zone. Moreover, at the same CO2 injection rate, injection into aquifer leads to produce more oil compared to CO2 injection into the pay-zone.

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