Speaker
Description
Storing CO2 in geological formations is a crucial method for mitigating climate change. However, CO2 leakage poses a threat, with faults representing a significant concern. Accurately simulating fault at different scales is crucial to predict the consequences of CO2 injection and storage at the field-scale. However, this task can be challenging, particularly in the early stages of a storage project since 1) knowledge of the storage reservoir is limited, 2) Obtaining high-quality well logs, cores, and seismic data is expensive, and 3) Resolving the impact of fine-scale fault features on field-scale storage assessment is computationally expensive.
This study proposes a fast tool for CO2 leakage risk assessment that addresses these challenges at both the project screening stage and advanced stages of project planning. The tool uses a vertically integrated reservoir model coupled with an upscaled fault leakage function based on source/sink relations. The fault is conceptualized as an increased vertical permeability through the caprock (due to the fracture network in the fault damage zone) and a reduced horizontal permeability through the reservoir (due to fault throw and fault core). A steady-state flow approximation is used to estimate CO2 leakage along the fault. Certain fault properties are geomechanically constrained to reflect the impact of pressure changes within the reservoir-caprock system. Geomechanical effects on fluid flow are modeled by relating porosity, permeability amongst several other parameters to effective stress using constitutive relations.
This study presents results validating the fault leakage function using 3D reservoir simulations. Example simulations are also shown to illustrate 1) impact of fault leakage on storage capacity, 2) impact of geomechanically constrained fault parameters such as capillary entry pressure and permeability on fault leakage for an example storage site located within Malay Basin. The fast model presented in this study is a valuable tool for identifying uncertainties in key fault parameters and other constitutive relations that affect the behavior of the storage reservoir and potential fault leakage outcomes. By incorporating this tool into the site screening stage, stakeholders can quickly assess the risk of CO2 leakage and evaluate the feasibility of the storage site under wide range of injection conditions.
| Country | UK |
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