Carbonate Cement Dissolution during a Cyclic CO ₂ Enhanced Oil Recovery Treatment

Geological sequestration of CO 2 in the subsurface: lessons from CO 2 injection enhanced oil recovery projects in oilfields

“…Thus although dissolution and dissociation of CO 2 should lead to the generation of both aqueous bicarbonate and acidity, the hydrogen ions must be involved (used) in other geochemical processes (for example R2b). Smith et al (1991) and Smith (1993Smith ( , 1998 observed similar patterns of increased calcium and magnesium concentrations in water produced in four other cyclic CO 2 injection projects, although geochemical analyses were insufficiently detailed to examine correlations with other parameters. The dataset in Smith (1998) is more thorough than others published since it includes aqueous silica and aluminium.…”

“…However, adding CO 2 to subsurface brines will lead to dissolution and then dissociation to form an acidic solution (R2a 8,: b) 1983;Shuler et al 1989;Bowker 8,: Shuler 1991;Smith 1998) reveal the clearest picture of what will happen when CO 2 is injected into the subsurface as a means of disposal or storage. All three field-based case studies explored above lead to the conclusion that carbonate mineral dissolution is the predominant result of injecting CO 2 into rocks that contain carbonate minerals.…”

“…This was also observed during a cyclic-CO 2 treatment conducted at Cole Creek field, Wyoming USA. In that example, the downhole pump scaled so badly that it was completely destroyed within a matter of a few weeks (Smith 1993(Smith , 1998Smith et al 1991). It is likely that the injected CO 2 initially dissolved carbonate minerals in the reservoir thus increasing both the aqueous calcium and bicarbonate concentrations.…”

“…1) into Cretaceous and Carboniferous reservoir sandstones in Wyoming, USA (Table 1), were published by Smith et al (1991) and Smith (1993Smith ( , 1998.…”

“…Smith et al (1991) and Smith (1993Smith ( , 1998 observed similar patterns of increased calcium and magnesium concentrations in water produced in four other cyclic CO 2 injection projects, although geochemical analyses were insufficiently detailed to examine correlations with other parameters. The dataset in Smith (1998) is more thorough than others published since it includes aqueous silica and aluminium. Aqueous silica increased following CO 2 injection and then proceeded to decrease in the same way as aqueous calcium and magnesium (Fig.…”