CO₂ Diffusion and Dispersion in Porous Media: Review of Advances in Experimental Measurements and Mathematical Models

Abstract

CO 2 molecular diffusion in subsurface porous media is one of the key mechanisms in high-pressure−high-temperature CO 2 geosequestration and CO 2 -based enhanced oil recovery projects. The mass transfer rate of injected supercritical CO 2 and its dissolution in reservoir fluids are mainly described by the gas diffusion coefficient. Over the past decades, numerous efforts have been made to investigate the CO 2 molecular diffusion process in both hydrocarbon reservoirs and saline aquifers. However, various experimental methods and mathematical models with simplified assumptions were used to determine the CO 2 diffusivity, which sometimes led to inaccurate or contradicting results. Hence, it is essential to critically review and compare the CO 2 -diffusion-related literature for better application in geoscience, chemical, and petroleum engineering fields. In this review, we critically review the physics of CO 2 diffusion in porous and nanoporous media, including the diffusion theory, factors affecting the CO 2 diffusion coefficient in hydrocarbon reservoirs and saline aquifers, analysis of laboratory measurement methods, their advantages and disadvantages and limitations, and also evaluation of previously developed mathematical models and their uncertainties and empirical correlations, in detail. Additionally, we briefly discuss CO 2 dispersion in porous media from various aspects. Finally, potential research areas related to CO 2 diffusion in porous media are proposed.

Quantification of the Impact of Acidified Brine on Fracture-Matrix Transport in a Naturally Fractured Shale Using in Situ Imaging and Modeling

“…Published matrix tortuosity values at similar spatial scales are the most directly comparable as reviews of previous studies have observed scale dependence in field measurements, similar to the scale dependence observed for dispersion . At the laboratory scale, the typical approach for the quantification of diffusion relies on bulk measurements of gas diffusion into or through samples and corresponding analytical model fits. ,− The methods in this study are analogous to these approaches, with the exception that an analytical model can be applied to every voxel of the image-based data, as opposed to typical bulk sample-average measurements. This image-based method results in hundreds of measurements of the matrix tortuosity in a given sample.…”

Comprehensive Outlook into Critical Roles of Pressure, Volume, and Temperature (PVT) and Phase Behavior on the Exploration and Development of Shale Oil

“…78 The lack of consensus in predicting the phase behavior of shale oil via EOS makes further studies essential to improve understanding of these complex systems. 79 Energy & Fuels A brief overview of several empirical correlations and ML models for predicting the main PVT properties is provided in Table 1. Most of the correlations in this review do not use oil compositions as inputs; instead, they rely upon more general parameters such as specific gravity.…”

“…It was found that the bubble-point pressure in the bulk region increased slightly . The lack of consensus in predicting the phase behavior of shale oil via EOS makes further studies essential to improve understanding of these complex systems …”

Minireview of Microscopic CO2 Interactions with Fluids and Minerals in Shale: Advances and Outlook

“…Several recent reviews have discussed the advances of understanding phase behaviors, molecular diffusion, and miscibility during CO 2 -EOR in tight formations. These reviews provided rich information on CO 2 -EOR technologies but did not focus on microscopic interactions of CO 2 with fluids and minerals in shale.…”