168 / 2021-11-02 18:04:20

Factors influencing potential CO2 storage capacity in shales

CO2 storage capacity in shales,CO2 storage

This article aims at presenting research on the sorption of carbon dioxide on shales, which will allow to estimate the possibility of CO2 injection into the volume of shale rocks. The clay minerals such as kaolinite, illite, montmorillonite and chlorite in the shale rocks are known for their sorption properties. This allows to assume common statement that sorption occurs mostly on organic content of shale since part of the gas is sorbed in clay minerals this can lead to underestimation of amount of carbon dioxide which can be stored in shale reservoir.

In previous studies it has been established that the adsorption of carbon dioxide for a given sample of the material is always greater than that of methane (Heller and Zoback, 2014), moreover, carbon dioxide is the preferred gas if adsorption takes place in the presence of both gases (Cecilia et al., 2018). It is known that the greater the content of organic matter in shale, the greater its suitability as a source of shale gas and a carbon dioxide reservoir (Ortiz Cancino et al., 2017; Zhou et al., 2018). Also the common knowledge is that presence of clay minerals has a positive effect on the sorption capacity of shale, but its influence is strongly covered by the content of organic matter (Bi et al., 2016; Gasparik et al., 2014). When organic content is particularly low and is no more than 1% of mineral composition, then sorption occurs on clay minerals almost exclusively, although amounts of sorbed gas are significantly lower than with higher organic content (Luo et al., 2015; Wang and Yu, 2016).

The shale storage capacity for carbon dioxide allows to calculate the amount of gas, which can be injected into shale formation and trapped in pores and voids as well as with bonding surface mechanism in porous solid. The mechanism is not homogenous and can be considered as adsorption on rock surface, dissolution and other (in much lesser extent) phenomena (Kang et al., 2011). As shales present nearly negligible permeability appearing together with seal over the petroleum reservoirs they are considered as attractive place for carbon dioxide sequestration. Another advantage is preference in sorption CO₂ over the natural gas due to molecular swapping mechanism, which is promoting methane to desorb and staying in free phase while CO₂ is sorbed on pores surface.

This article aims at presenting research on the sorption of carbon dioxide on shales, which will allow to estimate the possibility of CO2 injection into the volume of shale rocks. The clay minerals such as kaolinite, illite, montmorillonite and chlorite in the shale rocks are known for their sorption properties. This allows to assume common statement that sorption occurs mostly on organic content of shale since part of the gas is sorbed in clay minerals this can lead to underestimation of amount of carbon dioxide which can be stored in shale reservoir.

In previous studies it has been established that the adsorption of carbon dioxide for a given sample of the material is always greater than that of methane (Heller and Zoback, 2014), moreover, carbon dioxide is the preferred gas if adsorption takes place in the presence of both gases (Cecilia et al., 2018). It is known that the greater the content of organic matter in shale, the greater its suitability as a source of shale gas and a carbon dioxide reservoir (Ortiz Cancino et al., 2017; Zhou et al., 2018). Also the common knowledge is that presence of clay minerals has a positive effect on the sorption capacity of shale, but its influence is strongly covered by the content of organic matter (Bi et al., 2016; Gasparik et al., 2014). When organic content is particularly low and is no more than 1% of mineral composition, then sorption occurs on clay minerals almost exclusively, although amounts of sorbed gas are significantly lower than with higher organic content (Luo et al., 2015; Wang and Yu, 2016).

The shale storage capacity for carbon dioxide allows to calculate the amount of gas, which can be injected into shale formation and trapped in pores and voids as well as with bonding surface mechanism in porous solid. The mechanism is not homogenous and can be considered as adsorption on rock surface, dissolution and other (in much lesser extent) phenomena (Kang et al., 2011). As shales present nearly negligible permeability appearing together with seal over the petroleum reservoirs they are considered as attractive place for carbon dioxide sequestration. Another advantage is preference in sorption CO₂ over the natural gas due to molecular swapping mechanism, which is promoting methane to desorb and staying in free phase while CO₂ is sorbed on pores surface.