摘要：Faults can act as barriers to fluid flow in sedimentarybasins, hindering the migration of buoyant fluids in the subsurface,trapping them in reservoirs, and facilitating the build-up of vertical fluidcolumns. The maximum height of these columns is reliant on the retentionpotential of the sealing fault with regards to the trapped fluid. Severaldifferent approaches for the calculation of maximum supported column heightexist for hydrocarbon systems. Here, we translate these approaches to thetrapping of carbon dioxide by faults and assess the impact of uncertaintiesin (i) the wettability properties of the fault rock, (ii) fault rockcomposition, and (iii) reservoir depth on retention potential. As withhydrocarbon systems, uncertainties associated with the wettability of aCO2–brine–fault rock system for a given reservoir have less of animpact on column heights than uncertainties of fault rock composition. Incontrast to hydrocarbon systems, higher phyllosilicate entrainment into thefault rock may reduce the amount of carbon dioxide that can be securelyretained due a preferred CO2 wettability of clay minerals. Thewettability of the carbon dioxide system is highly sensitive to depth, witha large variation in possible column height predicted at 1000 and 2000 mof depth, which is the likely depth range for carbon storage sites. Our results showthat if approaches developed for fault seals in hydrocarbon systems aretranslated, without modification, to carbon dioxide systems the capacity ofcarbon storage sites will be inaccurate and the predicted security ofstorage sites erroneous.
