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Keywords

CO2 geological storage, injectivity impairment, clay-rich sandstone, fines migration, mineral dissolution

Document Type

Research Article

Abstract

Sustained injectivity is a controlling operational requirement for geological CO2 storage in deep saline aquifers because near-wellbore permeability loss can restrict injection rates, accelerate pressure build-up and reduce storage efficiency. In sandstone reservoirs containing reactive or mobile clay minerals, CO2-saturated brine may induce coupled geochemical and colloidal processes that cannot be interpreted through bulk porosity change alone. This review critically synthesises evidence on CO2-brine-rock interaction, clay mineral response, fines detachment, pore-throat restriction and injectivity impairment in sandstone systems. The reviewed literature indicates that mineral dissolution, secondary precipitation, salt precipitation, wettability alteration and fines migration can operate simultaneously, but their effects on permeability are not equivalent. Dissolution may locally enlarge pore space, whereas secondary products and mobilised particles can selectively block hydraulically critical pore throats. A central argument developed here is that, in clay-rich sandstone, rapid injectivity decline is more plausibly governed by the coupled sequence of CO2-induced acidification, clay-grain bond weakening, fines detachment, transport and redeposition than by extensive bulk mineral dissolution alone. The distinct contribution of this review is a diagnostic mechanism-ranking framework that separates the initiating geochemical trigger from the immediate hydraulic damage mechanism and links reservoir physicochemical conditions, clay stability, particle mobilisation, pore-throat retention and engineering-scale injectivity response. The synthesis also identifies key experimental gaps, particularly the limited number of studies integrating dynamic CO2-saturated brine flooding with effluent fines monitoring and pre-/post-flood X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) or micro-computed tomography (CT) characterisation. The framework is intended to support future laboratory designs and risk assessment for clay-bearing saline aquifers.

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Publication Date

30-6-2026

First Page

35

Last Page

49

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