Reactive Transport Simulation of Silicate-Rich Shale Rocks when Exposed to CO2 Saturated Brine Under High Pressure and High Temperature

TL;DR

This paper uses reactive transport modeling to simulate chemo-mechanical interactions in silicate-rich shale rocks exposed to CO2 saturated brine at high pressure and temperature, assessing mineral reactions and porosity changes.

Contribution

It demonstrates the application of reactive transport models to replicate pore-scale reactions in shale rocks under CO2 storage conditions, providing insights without extensive experimental testing.

Findings

Significant mineral dissolution and precipitation observed

Porosity increase of approximately 1% after 14 and 28 days

Reactive transport modeling effectively captures chemo-mechanical interactions

Abstract

This study examines the feasibility of carbon dioxide storage in shale rocks and the reliability of reactive transport models in achieving accurate replication of the chemo-mechanical interactions and transport processes transpiring in these rocks when subjected to CO2 saturated brine. Owing to the heterogeneity of rocks, experimental testing for adequate deductions and findings, could be an expensive and time-intensive process. Therefore, this study proposes utilization of reactive transport modeling to replicate the pore-scale chemo-mechanical reactions and transport processes occurring in silicate-rich shale rocks in the presence of CO2 saturated brine under high pressure and high temperature. For this study, Crunch Tope has been adopted to simulate a one-dimensional reactive transport model of a Permian rock specimen exposed to the acidic brine at a temperature of 100 {\deg}C and pressure of 12.40 MPa (1800 psi) for a period of 14 and 28 days. The results demonstrated significant dissolution followed by precipitation of quartz rich phases, precipitation and swelling of clay rich phases, and dissolution of feldspar rich phases closer to the acidic brine-rock interface. Moreover, porosity against reaction depth curve showed nearly 1.00% mineral precipitation occur at 14 and 28 days, which is insufficient to completely fill the pore spaces.