Sensitivity of Reservoir and Operational Parameters on the Energy Extraction Performance of Combined CO 2 -EGR–CPG Systems

Justin Ezekiel, Diya Kumbhat, Anozie Ebigbo, Benjamin M. Adams and Martin O. Saar
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Justin Ezekiel: Geothermal Energy and Geofluids Group, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland
Diya Kumbhat: Geothermal Energy and Geofluids Group, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland
Anozie Ebigbo: Geothermal Energy and Geofluids Group, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland
Benjamin M. Adams: Geothermal Energy and Geofluids Group, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland
Martin O. Saar: Geothermal Energy and Geofluids Group, Department of Earth Sciences, ETH Zurich, Sonneggstrasse 5, 8092 Zurich, Switzerland

Energies, 2021, vol. 14, issue 19, 1-21

Abstract: There is a potential for synergy effects in utilizing CO 2 for both enhanced gas recovery (EGR) and geothermal energy extraction (CO 2 -plume geothermal, CPG) from natural gas reservoirs. In this study, we carried out reservoir simulations using TOUGH2 to evaluate the sensitivity of natural gas recovery, pressure buildup, and geothermal power generation performance of the combined CO 2 -EGR–CPG system to key reservoir and operational parameters. The reservoir parameters included horizontal permeability, permeability anisotropy, reservoir temperature, and pore-size-distribution index; while the operational parameters included wellbore diameter and ambient surface temperature. Using an example of a natural gas reservoir model, we also investigated the effects of different strategies of transitioning from the CO 2 -EGR stage to the CPG stage on the energy-recovery performance metrics and on the two-phase fluid-flow regime in the production well. The simulation results showed that overlapping the CO 2 -EGR and CPG stages, and having a relatively brief period of CO 2 injection, but no production (which we called the CO 2 -plume establishment stage) achieved the best overall energy (natural gas and geothermal) recovery performance. Permeability anisotropy and reservoir temperature were the parameters that the natural gas recovery performance of the combined system was most sensitive to. The geothermal power generation performance was most sensitive to the reservoir temperature and the production wellbore diameter. The results of this study pave the way for future CPG-based geothermal power-generation optimization studies. For a CO 2 -EGR–CPG project, the results can be a guide in terms of the required accuracy of the reservoir parameters during exploration and data acquisition.

Keywords: CO 2 -plume geothermal (CPG); enhanced gas recovery (EGR); combined CO 2 -EGR–CPG system; sensitivity analysis; reservoir simulation; geothermal power generation (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2021
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (5)

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