Multiscale Assessment of Caprock Integrity for Geologic Carbon Storage in the Pennsylvanian Farnsworth Unit, Texas, USA

Leakage pathways through caprock lithologies for underground storage of CO2 and/or enhanced oil recovery (EOR) include intrusion into nano-pore mudstones, flow within fractures and faults, larger-scale sedimentary heterogeneity (e.g., stacked channel deposits). To assess multiscale sealing integrity the system that overlies Morrow B sandstone reservoir, Farnsworth Unit (FWU), Texas, USA, we combine pore-to-core observations, laboratory testing, well logging results, noble gas analysis. A cluster analysis combining gamma ray, compressional slowness, other logs was combined with caliper responses triaxial rock mechanics testing to define eleven lithologic classes across upper shale Thirteen Finger limestone units, estimations dynamic elastic moduli fracture breakdown pressures (minimum horizontal stress gradients) each class. Mercury porosimetry determinations column heights in formations yield values exceeding reservoir height. Noble profiles provide a “geologic time-integrated” assessment fluid reservoir-caprock system, measurements consistent decades-long EOR water-flooding, lower being long-term geohydrologic isolation. Together, these data suggest an excellent capacity FWU limits injection pressure increases accompanying carbon activities.