Incorporating reaction-rate dependence in reaction-front models of wellbore-cement/carbonated-brine systems

Real Time 3D Observations of Portland Cement Carbonation at CO2 Storage Conditions

“…The volumetric growth rates of the carbonated and porous silica regions were found to be 2.5 × 10 –3 ± 8 × 10 –5 and 1 × 10 –3 ± 5 × 10 –5 mm 3 /min for the first flow phase and 7.0 × 10 –4 ± 1.1 × 10 –4 and 1.8 × 10 –3 ± 8 × 10 –5 mm 3 /min for the second flow phase, consistent with previous reports of cement alteration slowing with time. 14 , 19 This slowdown arises from a change in the properties of the cement during the course of experiment, in particular, the growth of the dense carbonated zone 14 , 44 with low permeability that hinders the transport of reactants into the unreacted cement. In addition, the distance of diffusion of the reactants from the channel to the unreacted cement increases with time, which also contributes to slowing down the carbonation processes.…”

“…It has been observed that fractures present in cement can either close (self-seal) or open upon carbonation. Self-sealing is usually caused by precipitation of CC̅ 17 , 18 but may also be a result of cement swelling 10 or cement deformation, 19 whereas fracture opening is typically caused by the dissolution of cement compounds 20 and/or stresses induced by crystal precipitation. 21 Several studies attempting to explain the sealing behavior of fractures have emphasized the importance of flow rate, either in terms of Darcy flux 22 or residence time.…”

“… 21 Several studies attempting to explain the sealing behavior of fractures have emphasized the importance of flow rate, either in terms of Darcy flux 22 or residence time. 12 , 19 , 23 In connected fractures running parallel to the wellbore, the CO 2 fluid can reach high flow rates driven by pressure gradients. 24 , 25 Newell et al stated that the potential leakage rates calculated from a natural CO 2 producer with a wellbore permeability between 1 and 10 mD (inferred over a single 3 m interval) are around 0.3–3 mL/h.…”

Remediation of Annular Gas Migration along Cemented Wellbores Using Reactive Mineral Fluids: Experimental Assessment of Sodium Bicarbonate and Sodium Silicate-Based Solutions

“…Conversely, however, if dissolution dominates, then reactive transport could conceivably lead to extensive cement degradation and self-enhanced seepage, with sealing integrity worsening over time [65]. Numerical models have shown that the conditions under which reactive transport is self-sealing vs. non-sealing can be circumscribed quite well in terms of the initial defect size and fluid residence time [52,60,61,[66][67][68][69]. Specifically, sufficient time will be required for dissolution of cement phases to neutralise the carbonic acid and buffer the CO 2 -rich fluid (initially in the pH 3-4 range [70]) to the more alkaline pH values required for carbonates to precipitate [48,66].…”

Acid Water–Rock–Cement Interaction and Multicomponent Reactive Transport Modeling

“…Portland cement is placed between the borehole steel casing and the surrounding rock at CO 2 injection sites to prevent gas or fluid leakage. During and after CO 2 injection, the resulting CO 2 -rich acid water may deteriorate the cement and favor undesired leaking (Walsh et al 2014;Iyer et al, 2017). Quantification of geochemical processes at the laboratory scale through MCRTM is therefore necessary to understand their occurrence under the reservoir/seal and wellbore conditions.…”