Swelling-induced self-sealing mechanism in fractured cap rock: Implications for carbon geosequestration

Document Type

Journal Article

Publication Title

AAPG Bulletin

Publisher

American Association of Petroleum Geologists

School

School of Engineering

RAS ID

62038

Comments

Yu, H., Zhang, Y., Lebedev, M., Meng, K., Chen, S., Verrall, M., . . . Iglauer, S. (2023). Swelling-induced self-sealing mechanism in fractured cap rock: Implications for carbon geosequestration. AAPG Bulletin, 107(7), 1091-1104. https://doi.org/10.1306/09232219136

Abstract

Carbon geosequestration (CGS) in geological formations is a technology that can drastically reduce anthropogenic greenhouse gas emissions. The CO2 injected into such storage formations is trapped beneath a cap rock, and it is thus obvious that cap rock sealing efficiency is an essential factor for secure CO2 storage. However, the exact effect of supercritical CO2 exposure to microfractured, clay-rich shale cap rock-note that shale cap rock commonly contains microfractures-is poorly understood. We imaged fractured cap rock shale samples before and after supercritical CO2 injection via x-ray micro computed tomography at high resolution in three dimensions (3.43 m3) and representative reservoir conditions (i.e., a high pressure of 15 MPa and an elevated temperature of 50°C). Clearly, the fractures closed when flooded with supercritical CO2, which was most likely induced by clay swelling. As a consequence, the fracture permeability dramatically decreased, significantly increasing containment security and derisking CGS projects. © 2023. The American Association of Petroleum Geologists. All rights reserved.

DOI

10.1306/09232219136

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