A review on the influence of CO2/shale interaction on shale properties: Implications of CCS in shales

• Published in: Energies
• Main Authors: Fatah, Ahmed, Bennour, Ziad, Ben Mahmud, Hisham, Gholami, Raoof, Hossain, Mofazzal
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI 2020
• Subjects: Science & Technology; Technology; Energy & Fuels; shale gas; CO(2)injection; CO(2)sequestration; CO(2)storage capacity; CO2; shale interaction; CARBON-DIOXIDE STORAGE; SUPERCRITICAL CO2 SATURATION; TRACE-ELEMENT DISSOLUTION; ENHANCED GAS RECOVERY; LIFE-CYCLE ASSESSMENT; SPONTANEOUS IMBIBITION; MECHANICAL-PROPERTIES; PORE STRUCTURE; CAPACITY ESTIMATION; GEOLOGICAL STORAGE; Carbonic acid
• Online Access: https://hdl.handle.net/20.500.11937/81161; https://doi.org/10.3390/en13123200

© 2020 by the authors. Carbon capture and storage (CCS) is a developed technology to minimize CO2 emissions and reduce global climate change. Currently, shale gas formations are considered as a suitable target for CO2 sequestration projects predominantly due to their wide availability. Compared to conventional geological formations including saline aquifers and coal seams, depleted shale formations provide larger storage potential due to the high adsorption capacity of CO2 compared to methane in the shale formation. However, the injected CO2 causes possible geochemical interactions with the shale formation during storage applications and CO2 enhanced shale gas recovery (ESGR) processes. The CO2/shale interaction is a key factor for the efficiency of CO2 storage in shale formations, as it can significantly alter the shale properties. The formation of carbonic acid from CO2 dissolution is the main cause for the alterations in the physical, chemical and mechanical properties of the shale, which in return affects the storage capacity, pore properties, and fluid transport. Therefore, in this paper, the effect of CO2 exposure on shale properties is comprehensively reviewed, to gain an in-depth understanding of the impact of CO2/shale interaction on shale properties. This paper reviews the current knowledge of the CO2/shale interactions and describes the results achieved to date. The pore structure is one of the most affected properties by CO2/shale interactions; several scholars indicated that the differences in mineral composition for shales would result in wide variations in pore structure system. A noticeable reduction in specific surface area of shales was observed after CO2 treatment, which in the long-term could decrease CO2 adsorption capacity, affecting the CO2 storage efficiency. Other factors including shale sedimentary, pressure and temperature can also alter the pore system and decrease the shale "caprock"seal efficiency. Similarly, the alteration in shales' surface chemistry and functional species after ...