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Numerical study of reservoir permeability effects on gravity changes associated with CO 2 geological storage: implications for gravimetric monitoring feasibility
Author(s) -
Goto Hiroki,
Ishido Tsuneo,
Sorai Masao
Publication year - 2020
Publication title -
greenhouse gases: science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.45
H-Index - 32
ISSN - 2152-3878
DOI - 10.1002/ghg.1974
Subject(s) - gravimetric analysis , permeability (electromagnetism) , plume , buoyancy , geology , petroleum engineering , injection well , soil science , mechanics , geotechnical engineering , chemistry , thermodynamics , physics , biochemistry , organic chemistry , membrane
Gravimetric methods are used for monitoring the migration of CO 2 stored in the reservoir. Reservoir permeability is crucial for injectivity and potentially important for gravity changes associated with CO 2 storage. Nevertheless, its effects on gravity changes have not been investigated systematically. After conducting numerical simulations of CO 2 injection and storage using models with varying permeability conditions (50–1000 mD), we calculated surface gravity changes. Results show that two mechanisms affect gravity decrease, related to differences in CO 2 density and in CO 2 spatial patterns. Under low‐permeability conditions, gravity decrease is minimal during injection because of increases in pressure and the resulting relative high density of CO 2 . Gravity decrease is enhanced after injection ceases because of the pressure release and resulting CO 2 expansion. These effects are strong at shallow depths, at which CO 2 is near the critical point and highly compressible. Under higher permeability conditions, rapid spreading of the CO 2 plume causes smaller gravity reduction rate after some decades of injection. After injection ceases, upward CO 2 migration because of buoyancy and plume spreading increase gravity above the injection zone. The time required for gravity change detection depends on permeability. Detection during injection can be made earlier under higher permeability conditions and under lower permeability conditions after injection ceases. These points suggest that permeability affects the feasibility of gravimetric methods. Moreover, designing monitoring programs based on permeability and depth conditions is necessary for successful monitoring. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.