CO2 sequestration in deep saline aquifers — Mt. Simon, Knox Group, and other Illinois Basin storage formations. Implications for mineral and pore space rights.
Get Your Free Mineral ValuationTL;DR Deep saline aquifers are the primary U.S. target for permanent geologic CO2 sequestration. Major formations include the Mt. Simon Sandstone (Illinois Basin), Knox Group, Frio Formation (Gulf Coast), Broom Creek (North Dakota), and Madison Formation (Wyoming). Saline aquifers are not productive of oil or gas, so traditional mineral rights typically do not address them; the relevant ownership concept is pore space, which most U.S. states allocate to the surface owner.
Deep saline aquifers are subsurface rock formations — typically sandstones or carbonates — that contain water with high dissolved salt content (brine), unsuitable for drinking, agriculture, or industrial use. These formations sit thousands of feet below the surface, separated from useful groundwater by impermeable confining layers.
Saline aquifers are the primary target for permanent geologic CO2 sequestration because they offer enormous storage capacity, reliable confinement, and minimal interference with productive zones above.
Mt. Simon Sandstone — Cambrian-age sandstone underlying the Illinois Basin (Illinois, Indiana, Kentucky); primary CCS target for Wabash Valley and other midwestern projects
Knox Group — Ordovician carbonates underlying the Mt. Simon
Salem Limestone — Mississippian carbonate; selectively used for storage in Illinois
Frio Formation — Gulf Coast Tertiary sandstone; Louisiana and East Texas CCS projects
Broom Creek Formation — North Dakota Permian sandstone; primary North Dakota Class VI storage
Madison Formation — Wyoming Mississippian carbonate; multiple Wyoming CCS projects
Saline aquifers are typically not productive of oil or gas — they contain brine, not hydrocarbons. The legal question is who owns the void space (pore space) in the formation: the mineral owner or the surface owner?
Most U.S. states allocate pore space to the surface owner, particularly in jurisdictions with explicit statutory frameworks (Indiana, North Dakota, Wyoming). This means CCS lease payments and 45Q-related revenue typically go to the surface owner, not the mineral owner.
Mineral owners may still benefit indirectly: CCS projects must respect existing mineral rights and cannot interfere with current or reasonably anticipated future oil and gas operations. Mineral owner consent or non-objection may be required during Class VI permitting.
Buckhead Energy buys mineral and royalty interests in saline-aquifer storage areas.
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