Supercritical CO2 flow through a layered silica sand/calcite sand system: Experiment and modified maximal inscribed spheres analysis

Abstract

A core-scale experiment in which supercritical carbon dioxide (scCO 2 ) was flowed through a brine-saturated sample consisting of a layer of silica sand, a layer of calcite sand, and another layer of silica sand from inlet to outlet was performed, and compared to a similar experiment in which nitrogen was flowed through the same sample at the same orientation, effective stress, and temperature. The core-scale experiments were monitored using x-ray computed tomography to examine the flow paths of the fluids. Both nitrogen and scCO 2 showed gravity override, however both flowed through a very narrow pathway through the calcite sand, and a broader pathway through the silica sand. Synchrotron computed microtomography volumes were acquired for sub-samples of each type of sand and reconstructions of the sand samples were analyzed using the Maximal Inscribed Spheres method modified for mixed-wet conditions to estimate characteristic curves for a number of contact angles. These characteristic curves are used to explain and interpret the experimental results.

Next generation models of carbonate mineral growth and dissolution

“…Many factors affect the extent and rate of carbonate mineral trapping and its effect on both storage reservoirs and cap‐rocks. Physical or hydrological factors include the distribution and mixing of fluids within the host formation, heterogeneity, and wetting behavior of the carbon dioxide plume . Geochemical factors include the rate of dissolution of native minerals that provide the source of cations for carbonate mineral growth and the rate of precipitation of the carbonate minerals themselves .…”

“…In modeling these effects, physical intercalation of carbon dioxide at the pore scale is seemingly well‐understood, but other more intractable factors such as dealing with heterogeneity and long‐term effects are still topics of active research . For geochemical effects, reactive transport simulations represent the best possibility of coupling the physics of fluid flow and mixing in porous media with mineral reactivity.…”

“…Physical or hydrological factors include the distribution and mixing of fl uids within the host formation, heterogeneity, and wetting behavior of the carbon dioxide plume. [2][3][4][5] Geochemical factors include the rate of dissolution of native minerals that provide the source of cations for carbonate mineral growth and the rate of precipitation of the carbonate minerals themselves. 6 Additional physico-geochemical factors include the eff ects of precipitation on porosity and permeability of the reservoirs and cap-rocks, i.e.…”

Quantifying fracture geometry with X-ray tomography: Technique of Iterative Local Thresholding (TILT) for 3D image segmentation

“…Over the past two decades, X-ray computed tomography (xCT) has become a valuable tool for 3D visualization and characterization of geological specimens [1][2][3][4][5][6][7][8][9], including fracture geometries [10][11][12][13][14][15][16][17][18][19][20][21], pore networks [22][23][24][25][26][27][28][29][30][31], crystal sizes [32,33], and mineral phases [3,[34][35][36][37][38][39]. xCT imaging is indispensable for non-destructive observation of geometry of fractures, which is important because fractures provide preferential flow conduits and often dominate mass transfer in geological materials.…”

“…xCT imaging is indispensable for non-destructive observation of geometry of fractures, which is important because fractures provide preferential flow conduits and often dominate mass transfer in geological materials. xCT imaging has been used to provide valuable insights in core-flow experiments designed to investigate fractures in the context of geohydrological, geochemical, and geomechanical processes of the deep subsurface, such as CO 2 geological storage [20,30,40] and oil and gas operations [13-15, 17, 41-46]. Quantitative characterizations of fracture geometries have advanced our understanding of fracture hydrodynamics [13,17,21,[47][48][49], reactivity [11,24,25,35,36,47,[50][51][52][53], and mechanics [16,19,37].…”