Comprehensive Review of Property Alterations Induced by CO₂–Shale Interaction: Implications for CO₂ Sequestration in Shale

Abstract

CO2–shale interaction performs a crucial role in determining the capacity and leakage risk of CO2 storage in shale reservoirs. In this paper, the alterations of physical and chemical properties of shale triggered by CO2–shale interaction are reviewed, and then the implications for CO2 sequestration in shale formations are discussed. CO2–shale interaction induced the mineral alterations in shale and then further induced the pore structure alterations. The pore structure alterations are mainly controlled by mineral dissolution/precipitation and extraction and CO2 adsorption induced swelling in shale, which is closely related to the reservoir pressures and temperatures. Furthermore, the mineral and pore structure alterations may also influence the wetting behavior of shale. After CO2 exposure, the contact angle of shale increased, indicated the weakening in the hydrophilicity of the shale surface. The microscopic property alterations induced the macroscopic mechanical properties of shale to be weakened after CO2–shale interaction. The permeability variation of shale is significantly influenced by chemical–mechanical coupling effects including mineral dissolution/precipitation, adsorption induced swelling, wettability, and mechanical weakening induced by CO2–shale interaction. The shale property alterations will ultimately affect the CO2 storage capacity and security in shale. Future research needs to focus on the CO2–shale interaction covering multiple spatial and temporal scales at in situ conditions and considering the chemical–mechanical coupling effect on CO2 sequestration in shale.

Unconventional Reservoir Characterization of Patala Formation, Upper Indus Basin, Pakistan

“…Different types of porosity systems exist within organic-rich shales (e.g., kerogen pores, interparticle, intraparticle, and fracture-type pores). Permeability provides a direct estimate of shale gas potential and can be used to determine the productivity of shale gas reservoirs. − …”

“…Permeability provides a direct estimate of shale gas potential and can be used to determine the productivity of shale gas reservoirs. 21 − 23 …”

NMR Measurements for Gas Adsorption Characterization on Shale: State of the Art and Perspectives

“…The applications of NMR in underground resource utilization and the characterizations of shale gas adsorption have been comprehensively reviewed in other works, as listed in Table . The NMR technique was reviewed in the detection and characterization of the pore structure, , permeability of shale, methane diffusion, oil distribution, , and CO 2 –shale interaction . On the other hand, the reviews about shale gas adsorption focus on the traditional measurement method, , simulation method, and theoretical models; , the significance of NMR in adsorption measurement has not been comprehensively reviewed.…”

“…The NMR technique was reviewed in the detection and characterization of the pore structure, 21,23 permeability of shale, 21 methane diffusion, 15 oil distribution, 15,24 and CO 2 − shale interaction. 25 On the other hand, the reviews about shale gas adsorption focus on the traditional measurement method, 2,26 simulation method, 2 and theoretical models; 27,28 the significance of NMR in adsorption measurement has not been comprehensively reviewed. Here, we review the research on NMR measurements for shale gas adsorption characterization, including the basic understanding and peak spectrum recognition of NMR relaxometry results, the experimental method of NMR-based isothermal adsorption measurement, and the results obtained by different researchers.…”

Investigation on Capillary Force Recovery of Nanoparticle-Coated Shale after Supercritical CO2 Exposure: Implications for CO2 Sequestration

“…Storing carbon dioxide (CO 2 ) in the shale formations to realize carbon geo-sequestration (CGS) is believed to be one of the most promising means to cutting CO 2 emissions. − Basically, four trapping mechanisms deter sealed CO 2 from leakage to the atmosphere: structural trapping, , residual trapping, − dissolution trapping, , and mineral trapping. , The structural and residual trappings may take precedence over dissolution and mineral trappings in the first decade of the CGS program, , as the chemical reactions of the CO 2 –rock–brine system may take hundreds of years to be equilibrated . The capillary force, which is characterized by the following formula, is necessary for both structural trapping and residual trapping …”