Computational estimation of transport properties in poorly-consolidated formations for geological CO2 storage

Accurate estimation of physical properties of prospective formations is essential for the successful geological CO2 storage. Important physical properties such as porosity, permeability and electrical resistivity are typically obtained through laboratory measurements on core plugs or well-log data. When prospective formations for geological CO2 storage are poorly-consolidated, core recovery and well logging are very difficult and the estimation of physical properties becomes the main obstacle to evaluating the prospective formation. In this paper, we present a new approach to estimating physical properties of poorly-consolidated formation, which consists of acquiring undisturbed samples with epoxy impregnation, obtaining pore microstructures by X-ray CT, and numerically estimating physical properties using pore-scale simulations. To verify the reliability and applicability of the proposed method, we applied the method to a poorly-consolidated sample from a prospective formation in Korea. We also chose two more samples for comparison, one unconsolidated and one consolidated whose properties are known. Results showed that the computational estimation agrees well with the laboratory measurements for two comparative samples, and that for the test sample with unknown properties also lies in the expected ranges. This implies that the estimated properties of poorly-consolidated formation are reliable enough to use for the initial characterization of CO2 storage formations. We also performed two-phase flow simulations, which mimics the CO2 injection at the pore scale. From the simulations, we can roughly estimate the change in transport properties as a function of CO2 saturation. In conclusion, the proposed method can be a good tool to estimate transport properties for poorly-consolidated formations for geological CO2 storage.