Detection of potential leakage pathways from geological carbon storage by fluid pressure data assimilation

Abstract

One of the main concerns of geological carbon storage (GCS) systems is the risk of leakage through "weak" permeable areas of the sealing formation or caprock. Since the fluid pressure pulse travels faster than the carbon dioxide (CO 2) plume across the storage reservoir, the fluid overpressure transmitted into overlying permeable formations through caprock discontinuities is potentially detectable sooner than actual CO 2 leakage occurs. In this work, an inverse modeling method based on fluid pressure measurements collected in strata above the target CO 2 storage formation is proposed, which aims at identifying the presence, the location, and the extent of possible leakage pathways through the caprock. We combine a three-dimensional subsurface multiphase flow model with ensemble-based data assimilation algorithms to recognize potential caprock discontinuities that could undermine the long-term

Simulating seismic chimney structures as potential vertical migration pathways for CO2 in the Snøhvit area, SW Barents Sea: model challenges and outcomes

“…Uncertainty in porosity has less influence on CO2 mass migration than the uncertainty in formation permeability (Gonzalez-Nicolas et al 2012). Therefore, we focus on the variation of permeability.…”

“…CO2 migration was also very sensitive to the uncertainty from the permeability of fluid flow pathways and to the type of statistical distribution used to characterize it (Gonzalez-Nicolas et al 2012). Depending on the gravitational number the plume shape changes and the leakage rates are strongly affected.…”

“…This is because smaller porosity is expected to result in larger "leakage" rates (Gonzalez-Nicolas et al 2012). …”

“…This signifies that larger porosity causes shorter propagation of the pressure pulse and reduces the maximum overpressure, since the propagation of the overpressure pulse depends on porosity. Thus, in the case of larger porosity, the same amount of CO2 occupies a smaller region of the aquifer, hence retarding the attenuation of this pulse (Gonzalez-Nicolas et al 2012).…”

“…The shape of the plume also depends on porosity and lower porosity results in faster plume propagation and a higher likelihood of encountering "leaky" pathways (Gonzalez-Nicolas et al 2012). This is because smaller porosity is expected to result in larger "leakage" rates (Gonzalez-Nicolas et al 2012).…”