Assessing the Effect of Natural and Induced Fractures on Long-Term CO2 Storage in the Northern Appalachian Basin Using Thermo-Hydro-Mechanical Modeling
Abstract
Natural and induced fractures in a caprock could allow CO2 to migrate out of the intended storage reservoirs in the CO2 sequestration process. We evaluate, through the use of coupled hydro-mechanical numerical modeling, the effectiveness of the Cambrian-Ordovician caprock system in the northern Appalachian Basin for providing long-term containment of CO2 in the presence of existing and induced fractures. Resistivity image and acoustic image logs from wells in the study area were used characterize natural fractures in the caprock zone. The logs showed no compelling evidence of pervasive natural fracturing of the caprock; however, limited natural fractures occur in small isolated patches. Therefore, we modeled natural fractures as isolated features of limited size using the dual-porosity method. The modeling results show that the caprock is effective at preventing CO2 breakthrough in the presence of a natural fracture that partially penetrates the caprock; however, the caprock would be ineffective for containing CO2 if the fracture fully penetrates caprock. To assess induced fractures, coupled fluid-flow, geomechanical, and fracture mechanics modeling was conducted to model the effect of an induced fracture on the sealing integrity of the caprock. First, a fracture mechanics model was used to generate the injection-induced hydraulic fracture and calculate its dimensions (height, length, width). Then, a fluid-flow model was used to evaluate the impacts of the fracture on caprock sealing effectiveness. A significant observation is that the hydraulic fracture was confined to the reservoir (Rose Run sandstone) and did not extend upward into the caprock because the reservoir has the lower minimum horizontal stress. Our study shows that both natural and induced fractures can affect long term CO2 storage depending on size of natural fracture zone, geological and geomechanical properties of reservoir and caprock formations as well as injection parameters.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.H23A1636R
- Keywords:
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- 1822 Geomechanics;
- HYDROLOGY;
- 1847 Modeling;
- HYDROLOGY;
- 1858 Rocks: chemical properties;
- HYDROLOGY;
- 1895 Instruments and techniques: monitoring;
- HYDROLOGY