Composite Confining Systems: Rethinking Petroleum Seals for CO2 Storage

April 19, 2024 9:00 AM


Alex Bump, Ph.D.
Research Scientist Associate IV
Bureau of Economic Geology
Jackson School of Geoscience
The University of Texas at Austin


Petroleum accumulations prove the capability of geologic reservoirs, traps, and seals to store buoyant fluids safely, securely, and permanently.  That experience suggests targeting similar systems to sequester CO2 emissions in the quest to mitigate climate change.  Indeed, every storage project to date has done just that, and there is no question that petroleum-type reservoirs and seals work equally well for CO2.  However, the goal of permanent sequestration is fundamentally different from the familiar goal of petroleum production.  Injected CO2 need not remain concentrated, mobile, or recoverable.  In fact, it is more secure if it is none of those, which raises the possibility of rethinking the inherited wisdom.  This talk will explore composite confining systems, which we define as a multi-layer system of barriers with no a priori requirements for lateral continuity or maximum capillary entry pressure, but which create very long, tortuous flow paths for vertical migration.  The result is a system that disperses CO2 laterally and attenuates the mobile fraction through dissolution, residual trapping, local capillary trapping and small buoyant traps.  In petroleum, it would be called migration loss.  In climate change mitigation, it offers ultra-secure storage.

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