Pore matrix dissolution in carbonates: An in-situ experimental investigation of carbonated water injection

Carbon capture, utilization, and storage (CCUS) technology has shown rapid development in recent years as an important technology to reduce carbon emissions, of which CO 2 geological storage is an important part. Due to the complexity of CO 2 geological storage, especially the long period of mineralization storage, intensive studies have been conducted to reveal the mechanism of mineralization storage. This review presents a comprehensive understanding of the mineralization storage mechanism and its application prospects by introducing various experimental tools to deepen the characterization of pore-scale and core-scale changes during mineralization storage and promote the application of mineralization storage in large-scale carbon storage studies through geochemical simulations and field-scale demonstrations. This review summarizes representative multiscale studies of mineralization storage in typical reservoirs. The main findings are as follows: (1) For CO 2 −water−rock reactions, in addition to the influence of the inherent inhomogeneity of reservoir rocks (properties of mineral components, etc.), the environmental conditions of the reservoir (pH, temperature, pressure, etc.) have a strong influence on the dissolution and precipitation processes during mineralized storage. (2) The mineralization sealing process is accompanied by a complex evolution of pore-permeability properties. The mineral dissolution stage causes an increase in pore space and significantly improves the fluid injection capacity, while the mineral reprecipitation process causes problems such as pore throat blockage, which often affects the safety of sealing. (3) The modeling approach, combined with laboratory work, allows for large-scale and time-scale predictions. In addition, the current implementation of successful demonstration projects is summarized to promote the use of CO 2 storage in field engineering applications. Finally, directions for future development and research are proposed.

Section: Effects Of the Dissolution−precipitation Process Onmentioning

confidence: 99%

Section: Pore Scale Characteristics During Mineralization Storagementioning

confidence: 99%

Review on Multiscale CO₂ Mineralization and Geological Storage: Mechanisms, Characterization, Modeling, Applications and Perspectives

Sun,

Liu,

Cheng

et al. 2023

“…Increasing the flow rate, u, decreases the residence time, and a smaller residence time reduces the Da . Da ≫ 1 indicates that reaction kinetics are much faster than the transport rates over the core length under consideration, while Da < 1 indicates a transport-controlled process. , The residence time of the fluid during spontaneous imbibition is much longer than during the forced imbibition stage; hence, Da spontaneous imbibition ≫ Da forced imbibition . Therefore, the spontaneous imbibition stage was reaction-controlled and the forced imbibition stage was transport-controlled.…”

Section: Resultsmentioning

confidence: 99%

Geochemical Impact of High-Concentration Formate Solution Injection on Rock Wettability for Enhanced Oil Recovery and Geologic Carbon Storage

Oyenowo,

Wang,

Mirzaei-Paiaman

et al. 2024

This paper presents new data on core-scale wettability alteration of carbonate porous media with FM concentrations up to 30 wt % in NaCl brine. Experimental data from Amott tests, core floods, calcite dissolution experiments, and zeta potential measurements were analyzed to mechanistically understand the wettability alteration observed in the experiments. Static calcite dissolution tests showed that the degree of dissolution increased with increasing FM concentration in NaCl brine, even with an initially neutral pH. For example, the calcium concentration in the 30 wt % FM solution was 15.9 times greater than that in the NaCl brine with an initial pH of 7.0. Furthermore, reducing the initial solution pH from 7.0 to 6.1 for the 30 wt % FM solution caused the calcium ion concentration to increase by a factor of 3.2. Geochemical modeling and Raman analysis indicated that increased calcite dissolution was caused by interactions between calcium and FM ions. The 30 wt % FM solution with an initial pH of 6.1 yielded 4.7 times greater oil recovery than the NaCl brine in the spontaneous imbibition. The resulting Amott index indicated the wettability alteration to a water-wet state by the FM solution. The 30 wt % FM solution with an initial pH of 7.0 yielded only 30% greater oil recovery than the brine in the spontaneous imbibition; however, it reached nearly the same total oil recovery (spontaneous and forced) as the 30 wt % FM solution with an initial pH of 6.1. A numerical model was calibrated using core flood data, based on which the relative permeabilities indicated the core-scale wettability alteration by FM solutions. Results showed that increasing the FM concentration in the injection brine rendered the initially oil-wet core to a more water-wet state and that the in situ solution pH played an important role in wettability alteration by FM solution in carbonate media.

“…Therefore, understanding the mechanisms behind water flooding and carbon dioxide flooding is essential for developing and adjusting oil recovery strategies. In researching issues to improve ORR s, understanding the microscopic formation and distribution of residual oil, along with controlling factors, is the most crucial aspect, and of these factors, the pore structure of the reservoir plays a significant role. − …”

Section: Introductionmentioning

confidence: 99%

Flow Patterns and Pore Structure Effects on Residual Oil during Water and CO₂ Flooding: In Situ CT Scanning

Zhang,

Lin,

Ren

2023

Carbon dioxide (CO 2 ) enhanced oil recovery (EOR) is an important technology to achieve carbon neutrality by sequestering CO 2 underground while simultaneously recovering crude oil. Reservoir pore structure is a key factor influencing CO 2 EOR. In this study, we utilized advanced online in situ CT scanning and digital rock techniques to obtain, for the first time, evolution profiles of the finger area during water flooding and CO 2 flooding processes, quantitatively assessing the differences in fluid patterns. Additionally, we first introduced an innovative approach using advanced machine learning techniques, especially XGBoost and SHAP, to construct a predictive model of the relative change of oil phase occupancy (RCPOC) based on pore structure parameters and evaluated the importance of each pore structure parameter. Importantly, our results revealed that CO 2 can significantly increase the sweep efficiency area while substantially reducing residual oil saturation, in stark contrast to the relatively uniform water front observed during water flooding. Furthermore, we elucidated the critical role of capillary forces, demonstrating that water flooding primarily extracts trapped oil from small pores, while CO 2 flooding effectively extracts oil from larger pores. During CO 2 flooding, there is a positive correlation between coordination number, mean throat radius (MeanTR), and mean throat length (MeanTL) and the change in oil occupancy, whereas their influence during water flooding is limited. In summary, this study contributes to the understanding of flow patterns and pore structure effects on residual oil during water flooding and the CO 2 flooding processes. It also provides a novel approach based on pore structure parameters to predict RCPOC and assess the importance of influencing factors, thereby expanding our research perspective on this issue.