Geomechanical characterization and reservoir Simulation of a carbon storage project in e-m depleted Gas field in South Africa
| Autor: | Saffou, Eric |
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| Jazyk: | angličtina |
| Rok vydání: | 2020 |
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| Popis: | Philosophiae Doctor - PhD Geomechanical analysis and integrity assessment of hydrocarbon reservoirs upon depletion and injection are crucial to ensure that CO2 storage projects can be safely implemented. The Bredasdorp Basin in South Africa has great potential for CO2 storage, given its hugely available exploration data. However, there has not been any geomechanical characterization carried out on this basin to determine its integrity issues. This study aims to investigate the feasibility of a carbon storage project in the E-M depleted gas field. The preliminary geological assessment demonstrates that Zone 2 and Zone 3 display acceptable injectivity for CO2 injection of the E-M gas field. Seismic lines display faults that could affect the caprock's integrity during depletion and carbon storage. Geomechanical characterization provides a guideline as to how geomechanical analysis of depleted fields can be done for a safe CO2 sequestration practice. The geomechanical model constructed at a depth of 2570 m indicated that the magnitudes of the principal vertical, minimum, and maximum horizontal stresses in the field are respectively 57 MPa, 41 MPa, and 42-46 MPa. Fault and fracture stabilities were examined before and after depletion. It was found that faults and fractures in compartments C1 and C2 of the reservoir are stable before and after depletion, while normal faults (FNS8 and FNS9) in compartment C3 dipping SW were critically stressed. The minimum sustainable pressure of the reservoir determined by simulating depletion is 6 MPa. Below that, pressure depletion causes normal faulting in reservoir compartments C1 and C2. The maximum sustainable pressure, on the other hand, was found to be 25 MPa. The geomechanical studies also reveal that it is possible that the reservoir experienced compaction of 8 cm during depletion and will experience an uplift of 3.2 cm during 71 years of injection. The economic model of a CO2-enhanced gas recovery project in E-M gas field, the annual expenses (Aexp) of carbon capture and storage range between Zar20 3.31 × 109 and Zar20 4.10 × 109. The annual revenues (RA) were estimated to be Zar20 1.42 × 1010. The cash flow analysis derived from Aexp and RA confirms that enhanced gas recovery could partially offset the cost of CO2 storage if a minimum of 5 % of CO2 fraction is allowed in the natural gas recovered. Geological and geomechanical studies have demonstrated that carbon storage is physically feasible in the E-M gas field. However, the project's completion lies in the among the gas recovered to balance the cost of CO2. http |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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