Assessment model for estimating CO₂ commercial storage capacity in saline formations: A case study in Taiwan

The Commercial Storage Capacity is the storage capacity with geology, engineering, and economic considerations, and the estimate of the Commercial Storage Capacity is critical to carbon capture and storage project.In this study, an assessment model and calculation procedures for estimating Commercial Storage Capacity was proposed. Two modules, Capacity Module and Economic Module, were designed in the assessment model to evaluate the Commercial Storage Capacity. Capacity Module was used for generating an injection profile for an injection scenario, and Economic Module was used for analyzing the Commercial Storage Capacity and the corresponding net present value (NPV) for an injection scenario.A case study in Taiwan for estimating Commercial Storage Capacity in a saline formation was presented to illustrate and verify the assessment model and calculation procedures we proposed. After the calculation of the Capacity and Economic Modules, the Commercial Storage Capacity for CO₂ stored in Y-Sandstone formation in the Y-Gas field, northwestern Taiwan, was determined from total 60 injection scenarios. A linear relationship between Commercial Storage Capacity and the NPV was found, and that can be used to determine the optimal injection strategies to have the best Commercial Storage Capacity estimate or the highest NPV. Sensitivity analyses estimating the Commercial Storage Capacity and the NPV were done. We found that the carbon tax and the capture cost were the most sensitive economic parameters on the estimates of the NPV, and the discount rate was sensitive to the histogram of the Commercial Storage Capacity estimates.