Effects of CO2-CH4 Co-injection on the Performance of a Coupled Carbon Storage and Enhanced Oil Recovery Process
Abstract
This study aims at developing compositional simulation models of co-injecting CO2 and CH4 during a water-alternating-gas (WAG) process for assessing the efficiency of carbon capture and storage coupled with enhanced oil recovery (CCS-EOR). In this study, the volume of gas injection is fixed at surface conditions for various cases. A three-phase hysteresis and Henry's models are used to simulate residual and solubility trapping during the WAG process that imbibition and drainage processes occur repeatedly. Since CH4 is less compressible than CO2, it occupies more reservoir pore volume and causes high reservoir pressure resulting in improved EOR performance at an early time. However, EOR performance finally becomes lower with CH4 addition because of reduced miscibility and sweep efficiency, and oil recovery with CH4 addition is lower than that of CO2 injection case. Decreased gas displacement and sweep efficiencies cause poor hysteresis effect for residual trapping performance. Although the reduced sweep efficiency, solubility trapping performance does not change because reservoir average pressure with CH4 addition is greater than that of the CO2 injection case due to the compressibility effect. To compare the carbon storage efficiency, the index considering global warming potential (GWP) has been compared with various CH4 concentration models. Because the GWP of CH4 is about 28 times that of CO2, the co-injection WAG can further reduce greenhouse gas emissions into the atmosphere compared to the CO2 WAG. The above results indicate the significance of the integrated analysis for accurate CO2 sequestration in depleted or depleting hydrocarbon reservoirs under EOR.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMGC0970006C
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 1009 Geochemical modeling;
- GEOCHEMISTRY;
- 1847 Modeling;
- HYDROLOGY;
- 3999 General or miscellaneous;
- MINERAL PHYSICS