Mineral precipitation is ubiquitous in natural and engineered environments, such as carbon mineralization, contaminant remediation, and oil recovery in unconventional reservoirs. The precipitation process continuously alters the medium permeability, thereby influencing fluid transport and subsequent reaction kinetics. The diversity of preferential precipitation zones controls flow and transport efficiency as well as the capacity of mineral sequestration and immobilization. Taking barite precipitation as an example, previous studies have examined this process in porous and/or fractured media, but pore-scale mechanisms under varying flowing and geochemical conditions remain unexplored. In this study, we conducted real-rock microfluidic experiments to investigate the precipitation dynamics within a fractured porous system. Direct observations of the evolution of the porous structure and flow channel and quantifications of barite precipitation dynamics using X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), revealed two distinct precipitation regimes: precipitation on the fracture surface (regime I) and precipitation in the alteration zone (regime II). Through theoretical analysis of the rate of advection and nucleation, we defined a dimensionless number Da above which regime I occurs and regime II prevails otherwise. At the large Da number, when the precipitation rate is large compared with the flow rate, precipitation on the fracture surface is favored. As the precipitation regimes are expected to impact differently the permeability of the fractured porous media, the mass transfer across matrix and fractures, and the spatial distributions of coprecipitated contaminants, our work sheds light on accurately modeling reactive transport in fractured porous media across diverse applications.

The Hydraulic Fracturing Test Site 1 (HFTS-1) was a field study performed in the Wolfcamp Formation in the West Texas Permian (Midland) Basin, USA, with a focus on improving the efficiency of hydraulic fracturing. Investigating site-specific rock-fluid geochemical interactions during hydraulic fracturing is an important step to understanding the impact on formation shale porosity, permeability, and long-term shale gas production. During field operations in this region, hydraulic fracturing fluid (HFF) injection usually starts with a concentrated acid spearhead for rapid rock dissolution, followed by the injection of near-neutral pH slickwater containing chemicals and proppants. A multistep sequential injection approach was used to investigate different stages of rock-fluid interactions. The carbonate content in the host rock is important when acid spearhead is considered, as carbonate mineral dissolution is rapid and can result in porosity and permeability changes in the shale matrix. In this study, we designed flow-through experiments using fractured carbonate-rich and clay-rich Wolfcamp shale cores with (1) a short-time acid soaking step and (2) a long-term slickwater flow-through step to simulate the injection method used at HFTS-1. The fluid chemistry was analyzed. A thorough mineralogical progression [e.g., Calcium (Ca) dissolution and iron (Fe) redox progression] in the cores during HFF injection was also characterized and imaged by synchrotron microprobe. Reactive transport modeling was performed based on the experimental setup. The results showed that the acid spearhead is a crucial step in creating a reaction front by mineral dissolution, especially in carbonate-rich shales. A slight layer of ferrihydrite precipitated during the slickwater flow-through period. This study provides insights into potential geochemical impact due to hydraulic fracturing operations in the Permian Basin.

Fluid–rock interactions involving chemical dissolution, mechanical erosion, and multiphase flow are central to a wide range of geological and engineering processes, yet they remain poorly understood due to the lack of integrated in situ observation tools. Existing methods often compromise between spatial resolution and temporal dynamics. Here, we develop a real-rock microfluidic platform that enables simultaneous visualization and quantification of erosion dynamics in multiphase reactive systems. The platform integrates fluorescence microscopy, micro-particle image velocimetry, and ion chromatography to monitor the coupled evolution of solid–liquid–gas interfaces and flow velocity fields at micrometer-scale resolution. Microfluidic chips fabricated directly from limestone preserve natural mineral heterogeneity, and the platform enables direct observation of rock surface evolution and multiphase flow behavior. This facilitates decoupled analysis of chemical dissolution and mechanical erosion—two processes often difficult to isolate in traditional systems. Using this system, we investigate erosion during acid–rock interactions and identify a transition between two regimes—transport-limited and reaction-limited—controlled by CO2 bubble mobility. In the transport-limited regime, immobile bubbles confine flow to thin films, enhancing dissolution and particle detachment. In the reaction-limited regime, surface-adhered bubbles shield reactive areas and reduce shear stress, suppressing erosion. We derive scaling laws that distinguish chemical and mechanical erosion rates and validate a theoretical model for the critical Péclet number marking the regime transition. This study advances understanding of erosion under multiphase flow and introduces a versatile experimental framework for probing pore-scale reactive transport. The platform can be extended to other rock types and fluids, offering a powerful tool for studying geochemical, physical, and biological processes in complex subsurface environments.

Alquimia v1.0 is a generic interface to geochemical solvers that facilitates development of multiphysics simulators by enabling code coupling, prototyping and benchmarking. The interface enforces the function arguments and their types for setting up, solving, serving up output data and carrying out other common auxiliary tasks while providing a set of structures for data transfer between the multiphysics code driving the simulation and the geochemical solver. Alquimia relies on a single-cell approach that permits operator splitting coupling and parallel computation. We describe the implementation in Alquimia of two widely used open-source codes that perform geochemical calculations: PFLOTRAN and CrunchFlow. We then exemplify its use for the implementation and simulation of reactive transport in porous media by two open-source flow and transport simulators: Amanzi and ParFlow. We also demonstrate its use for the simulation of coupled processes in novel multiphysics applications including the effect of multiphase flow on reaction rates at the pore scale with OpenFOAM, the role of complex biogeochemical processes in land surface models such as the E3SM Land Model (ELM) and the impact of surface–subsurface hydrological interactions on hydrogeochemical export from watersheds with the Advanced Terrestrial Simulator (ATS). These applications make it apparent that the availability of a well-defined yet flexible interface has the potential to improve the software development workflow, freeing up resources to focus on advances in process models and mechanistic understanding of coupled problems.

Geochemically driven alterations of fractures in multi-mineral media can create altered layers (ALs) at the fracture-matrix interface. Spatial variations in the AL significantly influence mass transfer across the interface, and the hydraulic and mechanical properties of the fractured medium. A real-rock based microfluidic experiment reported spatial variations in AL thickness despite the initially smooth fracture surface, suggesting potential effects of matrix heterogeneity on AL development. However, the respective contribution of structural and mineralogical characteristics is still poorly understood. Using the microfluidic experimental data and a micro-continuum reactive transport model, we systematically evaluated how micro-porosity and initial mineral texture impact AL development and thus the overall reactive transport behaviors. Our simulation results confirmed that the extent of AL spatial variations, mainly controlled by mineralogical texture, influences the evolution of reaction and permeability in different ways. Accounting for spatial heterogeneity in mineral distribution produces “channeling” structures in ALs and lower overall reaction (by up to 35.6%), but larger permeability increase (by up to 9.8%). The characteristic length of the reactive mineral cluster was observed to dominate the internal texture of ALs. Whereas the presence of micro-porosity can enhance mineral accessibility via improving connectivity for flow and transport, and lead to both higher bulk reaction, that is, thicker ALs, and permeability enhancement. Considerations of surface roughness with characteristic length on the same order of magnitude as mineral texture did not change the overall development of AL, which further highlights the importance of accounting for rock matrix properties in predicting long-term evolution of fractured media. The resulting spatial variations of ALs and their impacts on bulk properties, however, are expected to be further complicated by the coupling of chemical and mechanical processes, and may trigger matrix disaggregation, erosion and other mechanisms of fractured media alteration.

Enhanced weathering (EW) is a CO2 removal (CDR) and sequestration strategy that accelerates the natural reactions of minerals that can store carbon from the atmosphere and biotic reactions. One method of EW is to apply finely ground silicate rocks to agricultural lands. EW has been demonstrated in laboratory and field tests, but great uncertainty remains regarding the life-cycle of using locally available rocks on candidate soils. We evaluate the life-cycle impacts, job creation, and cost of scenarios where fines and rocks mined from quarries in Oregon and Northern California are transported by truck and tilled into agricultural soils. Candidate quarry dust samples were classified as dacite, andesite, and olivine-bearing rocks, with EW potentials ranging from 125 to 760 kg CO2/metric tonne rock. We determined the olivine-bearing rock from Southern Oregon could achieve a levelized cost of CDR under the DOE Earthshot target of $100/t CO2, as long as application rates are 25 t/ha or more. Even andesite and dacite materials reach lower costs than commercial direct air capture technologies, with reduction in fines purchase and transport costs critical for achieving the Earthshot target. The results suggest that low-cost EW can be achieved using natural quarry materials, with average removal up to 2.2 t CO2e per hectare per year.

Porous materials in natural and engineered environments are subject to morphological changes resulting from interacting chemical and physical processes. The intricate nature of these coupled processes, occurring at various temporal and spatial scales, poses challenges in predicting alterations in porosity and permeability. Delineating the controls of mineral precipitation reactions is particularly challenging because it requires the implementation of nucleation criteria and growth mechanisms. By conducting pore-scale simulations, we investigated the impact of the amount and stochastic distribution of crystallites, controlled by nucleation, on pore geometry and permeability in two-dimensional porous structures. The observed relationships between porosity and permeability exhibit characteristics that differ from the ones that are typically applied in dissolving porous media because of the clogging effect. Additionally, we propose a stochastic framework that upscales the coevolution of permeability and porosity across length scales. This framework enables the upscaling of clogging behavior to continuum-scale simulations based on statistical probability distributions of permeability–porosity variations.

Understanding the complicated fluid dynamics and geochemistry coupling behaviors is the key to enhance CO2 storage efficiency and minimize the risks of leakage and mechanical failure in geologic CO2 storage (GCS) reservoirs. This review paper aims to discuss recent research advances associated with fluid dynamics and geochemistry coupling in GCS systems. Four research areas, i.e., flow-induced enhancement of mineral dissolution and precipitation, advanced imaging techniques based on digital core analysis techniques, advances in reactive transport modeling, and upscaling approaches from pore-scale to reservoir-scale, are covered by this review. Based on a comprehensive discussion on the research advances in the aforementioned research areas, current challenges and future research needs of fluid dynamics and geochemistry coupling in geologic CO2 storage are highlighted. Finally, this review discusses how the research in fluid dynamics and geochemistry coupling can help in developing sustainable geologic CO2 storage strategies that can contribute to achieving carbon neutrality goals.

Water scarcity and climate change are dual challenges that could potentially threaten energy security. Yet, integrated water–carbon management frameworks coupling diverse water- and carbon-mitigation technologies at high spatial heterogeneity are largely underdeveloped. Here we build a global unit-level framework to investigate the CO2 emission and energy penalty due to the deployment of dry cooling—a critical water mitigation strategy—together with alternative water sourcing and carbon capture and storage under climate scenarios. We find that CO2 emission and energy penalty for dry cooling units are location and climate specific (for example, 1–15% of power output), often demonstrating notably faster efficiency losses than rising temperature, especially under the high climate change scenario. Despite energy and CO2 penalties associated with alternative water treatment and carbon capture and storage utilization, increasing wastewater and brine water accessibility provide potential alternatives to dry cooling for water scarcity alleviation, whereas CO2 storage can help to mitigate dry cooling-associated CO2 emission tradeoffs when alternative water supply is insufficient. By demonstrating an integrative planning framework, our study highlights the importance of integrated power sector planning under interconnected dual water–carbon challenges.

Fluid-rock dissolution occurs ubiquitously in geological systems. Surface-volume scaling is central to predicting overall dissolution rate R involved in modeling dissolution processes. Previous works focused on single-phase environments but overlooked the multiphase-flow effect. Here, through limestone-based microfluidics experiments, we establish a fundamental link between dissolution regimes and scaling laws. In regime I (uniform), the scaling is consistent with classic law, and a satisfactory prediction of R can be obtained. However, the scaling for regime II (localized) deviates significantly from classic law. The underlying mechanism is that the reaction-induced gas phase forms a layer, acting as a barrier that hinders contact between the acid and rock. Consequently, the error between measurement and prediction continuously amplifies as dissolution proceeds; the predictability is poor. We propose a theoretical model that describes the regime transition, exhibiting excellent agreement with experimental results. This work offers guidance on the usage of scaling law in multiphase flow environments.