CO2 SEALING CAPACITY OF THE NEWARK RIFT BASIN MUDSTONES

Carbon Capture, Utilization, and Storage (CCUS) is an effective way to mitigate climate change by reducing anthropogenic CO₂ emissions. This study evaluates the sealing capacity of mudstones in the Newark Basin, one of the largest onshore sites in a series of Mesozoic rift basins in eastern North America considered for CCUS. The Newark Basin contains a cycle of reservoir and caprock layers needed to store and seal CO₂, which is essential for successful CCUS. The purpose of studying the Newark Basin for CCUS is to create an analogue for more ideal basins. The Newark Basin, while capable of storing CO₂, is not ideal due to the presence of faults and large population density in the region. This causes concern for leakage and fault reactivation. Mercury intrusion porosimetry (MICP) is used to determine the threshold capillary pressure for major caprocks in the basin, and to investigate its variability with lithology and other petrophysical properties. The maximum CO₂ retention column height is then evaluated using depth-dependent CO₂ density for various caprock layers in the basin. Given a wide range and significant uncertainty in CO₂ wettability and interfacial tension (IFT), we also perform a sensitivity analysis of the outcome to these parameters. Our results indicate that these Mesozoic rift basin mudstones represent good caprocks and are able to retain CO₂ column heights on the order of kilometers, which significantly exceeds an average reservoir thicknesses in the basin. Ideal basins may have reservoirs thick enough to store a useful amount of CO₂ but not thick enough as to cause pressure to break the overlying caprock. However, the uncertainty in available data on supercritical CO₂ (scCO₂) wettability, and in particular, on scCO₂ IFT, strongly affects the retention column height value, and the feasibility of CO₂ retention underground. Due to heterogeneity in rock mineral content, pore water salinity, pressure, and temperature there may be more uncertainty within these values. Overall, due to the cyclicity of reservoirs and caprock layers in the Newark Basin, there would be ample sealing capacity for CO₂ storage. Future work is needed in constraining CO₂ capillary parameters in order to reduce the uncertainty in critical CO₂ pressure.