The effect of CO2-induced dissolution on flow properties in Indiana Limestone: An in situ synchrotron X-ray micro-tomography study

Abstract

The injection of CO 2-rich fluids in carbonate rocks results in an evolution of the pore space, with consequent changes in the hydraulic properties of the reservoir; how these properties evolve, particularly for parameters relevant to multiphase flow e.g. P c (s), remains a topic of active research despite several decades of study. We have carried out an in situ synchrotron X-ray microtomography experiment to monitor pore structure evolution during dissolution of an Indiana Limestone core; the experiment involved flowing CO 2-saturated water through the core for 36 hours and resulted in 10 volumes corresponding to different temporal stages of the dissolution process. The injection parameters corresponded to the flow velocities expected near the well-bore region of a shallow aqueous CO 2 injection; fast flow rates with high reactant availability. Analysis of the tomographic data shows flow-enhanced dissolution i.e. channeling, and provides a timeresolved map of pore space alteration. Using the resulting 4D pore space volume, we modeled the evolution of capillary-pressure curves; this exercise demonstrates how pore structure evolution could impact the invasion and remobilization of non-wetting fluids, dramatically decreasing the entry pressure and the P C in some parts of the sample. The modeling of permeability, using a Stokes solver approach, quantified the relationship of porosity vs. permeability; we found that a modest increase in porosity, especially when the channeling system is more developed, greatly affects permeability. These results demonstrate how movement of CO 2 saturated brine near injected plumes might alter drainage dynamics near the plume boundary, thus leading to mobilization across subtle capillary barriers.

Porosity‐Permeability Evolution During Simultaneous Mineral Dissolution and Precipitation

“…Permeability evolution, however, cannot be as easily predicted. Previous literature has observed that an increase in porosity can result in an increase (Harbert et al., 2020; Luquot & Gouze, 2009; Voltolini & Ajo‐Franklin, 2019), decrease (Garing et al., 2015; Khather et al., 2018; Ma et al., 2019; Xiong et al., 2016) or no significant change in permeability (Harbert et al., 2020; Rötting et al., 2015) where the spatial distribution of reactions has a significant influence on the relationship between porosity and permeability (Beckingham et al., 2017; Bensinger & Beckingham, 2020; Crandell et al., 2012; Min et al., 2016; Noiriel et al., 2016; Steinwinder & Beckingham, 2019; Tenthorey & Scholz, 2002; Yoon et al., 2019). This is often related to flow and reaction conditions in terms of the dimensionless Peclet and Damköhler numbers, as summarized in Lichtner et al.…”

Homogenization of Dissolution and Enhanced Precipitation Induced by Bubbles in Multiphase Flow Systems

“…We now have temporally and 3‐D spatially resolved observations of mineral dissolution patterns in porous materials that have revealed the evolution of capillary pressure properties (Krevor et al, ; Voltolini & Ajo‐Franklin, ) and reaction rates (Menke et al, ), and in fractured materials, there are real‐time observations of dissolution leading to channelization (Deng et al, ), heterogeneous reaction (Noiriel et al, ), and the interplay between shear fracture, aperture, shear displacement, and permeability (Frash et al, , ). Microfluidics, a widely used technique, only recently has been applied at geological conditions through the development of high‐pressure/temperature capable systems (Campbell & Orr, ; Jiménez‐Martínez et al, ) and through the use of actual geologic materials as micromodels, which has allowed the investigation of wettability, matrix porosity, and mineral heterogeneity and thus greater fidelity of observations into subsurface processes (Ciceri & Allanore, ; Porter et al, ; Singh et al, ; Song et al, ).…”

From Fluid Flow to Coupled Processes in Fractured Rock: Recent Advances and New Frontiers

“…With time, instrumentation has improved through the application of industrial scanners (tens of μm), micro‐focus CTs (ones of μm), and high‐flux and synchrotron sources (tens of nm to ones of μm). In general, higher resolution comes at the cost of reduced specimen sizes: industrial CT works with several cm diameter specimens and synchrotron studies at a resolution of 1–7 μm operate on specimens of 3–9 mm (e.g., Godinho et al., 2019; McBeck et al., 2019; Renard et al., 2018; Voltolini & Ajo‐Franklin, 2019).…”