Composite confining systems: Rethinking geologic seals for permanent CO2 sequestration

Bump, Alexander P.; Bakhshian, Sahar; Ni, Hailun; Hovorka, Susan; Olariu, Marianna I.; Dunlap, Dallas; Hosseini, Seyyed A.; Meckel, Timothy A.

doi:10.1016/j.ijggc.2023.103908

Cited by 14 publications

(11 citation statements)

References 45 publications

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“…The invasion of injected CO 2 through these barriers is impeded by the capillary pressure contrast between the sandbody and fine-grained facies 8 , 15 . Existing reservoir modelings, experimental studies, and field-scale observations distinctly confirm the effectiveness of capillary trapping in the confinement of CO 2 plume 5 , 6 , 16 – 19 . The trapping mechanism of CO 2 beneath the flow barriers is called capillary heterogeneity trapping induced by the capillary pressure contrast between the sandbody and fine-grained barriers 20 , 21 .…”

Section: Introductionmentioning

confidence: 76%

“…Log values were normalized to a range of −80 to +20 MV and a cutoff value of − 30 MV was employed to distinguish between sandy and muddy facies. The footprint of the hydrocarbon-water contacts was used to estimate the range of barrier lengths 5 .…”

Section: Methodsmentioning

confidence: 99%

“…Thus, those barriers can impact reservoir connectivity and control the migration pathway of fluids 2 – 4 . This multi-layer system of discontinuous stratigraphic barriers has been defined as a composite confining system by Bump et al 5 . In the context of CO 2 storage applications, flow barriers can act as impediments to the buoyancy-driven upward migration of CO 2 plume, redirecting its migration primarily in a lateral direction 6 – 11 .…”

Section: Introductionmentioning

confidence: 99%

“…The heterogeneity in the spatial distribution and lateral continuity of discontinuous shale barriers as well as sand/shale ratios are among the major uncertainty associated with the composite confining systems 5 , 25 . These stratigraphic heterogeneities cannot be resolved deterministically using seismic data.…”

Section: Introductionmentioning

confidence: 99%

“…The main intention of this study is to consider a wide range of lateral continuity and density of shale barriers in geologic models and investigate the impact of these architectures and their characteristics on the migration and confinement of CO 2 within these formations. To this end, we employed a stochastic modeling approach to generate heterogeneous facies models containing horizontal discontinuous shale barriers populated in sand bodies, controlled by the correlation length of barriers and sand/shale ratios as factors constrained by Spontaneous Potential (SP) well-log data and observations of producing hydrocarbon fields 5 .…”

Section: Introductionmentioning

confidence: 99%

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Assessing the potential of composite confining systems for secure and long-term CO2 retention in geosequestration

Bakhshian,

Bump,

Pandey

et al. 2023

Sci Rep

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A potential geologic target for CO2 storage should ensure secure containment of injected CO2. Traditionally, this objective has been achieved by targeting reservoirs with overlying seals-regionally extensive, low permeability units that have been proven capable of retaining buoyant fluid accumulations over geologic time. However, considering that the amount of CO2 is limited by a decadal injection period, vertical migration of CO2 can be effectively halted by a composite system of discontinuous shale/silt/mudstone barriers in bedded sedimentary rocks. Here, we studied the impact of depositional architectures in a composite confining system on CO2 migration and confinement at reservoir scale. We stochastically generated lithologically heterogeneous reservoir models containing discontinuous barriers consistent with statistical distributions of net-sand-to-gross-shale ratio (NTG) and horizontal correlation lengths derived from well log data and observations of producing hydrocarbon fields in Southern Louisiana. We then performed an extensive suite of reservoir simulations of CO2 injection and post-injection to evaluate the sensitivity of CO2 plume migration and pressure response of the composite system to a series of geologic and fluid parameters including the lateral continuity of barriers, NTG, permeability anisotropy within the sand body, and capillary pressure contrast between the sand and shale facies. The results indicate that lateral continuity of barriers and NTG are the dominant controls on CO2 plume geometry and pressure build-up in the reservoir, while the impact of NTG is particularly pronounced. The significance of intraformational barriers becomes apparent as they facilitate the local capillary trapping of CO2. Those barriers improve the pore space occupancy by promoting a more dispersed shape of the plume and ultimately retard the buoyancy-driven upward migration of the plume post injection.

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