Chemical and Hydrodynamic Mechanisms for Long-Term Geological Carbon Storage

Abstract

Geological storage of CO 2 (GCS), also referred to as carbon sequestration, is a critical component for decreasing anthropogenic CO 2 atmospheric emissions. Stored CO 2 will exist as a supercritical phase, most likely in deep, saline, sedimentary reservoirs. Research at the Center for Frontiers of Subsurface Energy Security (CFSES), a Department of Energy, Energy Frontier Research Center, provides insights into the storage process. The integration of pore-scale experiments, molecular dynamics simulations, and study of natural analogue sites has enabled understanding of the efficacy of capillary, solubility, and dissolution trapping of CO 2 for GCS. Molecular dynamics simulations provide insight on relative wetting of supercritical CO 2 and brine hydrophilic and hydrophobic basal surfaces of kaolinite. Column experiments of successive supercritical CO 2 /brine flooding with highresolution X-ray computed tomography imaging show a greater than 10% difference of residual trapping of CO 2 in hydrophobic media compared to hydrophilic media that trapped only 2% of the CO 2 . Simulation results suggest that injecting a slug of nanoparticle dispersion into the storage reservoir before starting CO 2 injection could increase the overall efficiency of large-scale storage. We estimate that approximately 22% ± 17% of the initial CO 2 emplaced into the Bravo Dome field site of New Mexico has dissolved into the underlying brine. The rate of CO 2 dissolution may be considered limited over geological timescales. Field observations at the Little Grand Wash fault in Utah suggest that calcite precipitation results in shifts in preferential flow paths of the upward migrating CO 2 -saturated-brine. Results of hybrid pore-scale and pore network modeling based on Little Grand Wash fault observations demonstrate that inclusion of realistic pore configurations, flow and transport physics, and geochemistry are needed to enhance our fundamental mechanistic explanations of how calcite precipitation alters flow paths by pore plugging to match the Little Grand Wash fault observations.

Atomistic molecular dynamics simulations of H2O diffusivity in liquid and supercritical CO2

“…During the initial stages of CO 2 injection in geologic formations, a CO 2 -rich plume [12] is formed. Depending on the depth of injection, the plume can migrate towards (or away from) the surface, as a result of the density difference between the plume and the fluids in the surrounding formations.…”

Study of the impact of high temperatures and pressures on the equilibrium densities and interfacial tension of the carbon dioxide/water system

“…One defining stage in the process involves the safe storage of captured CO 2 . Among current options, geological storage of CO 2 is considered to be one of the most promising approaches [1,2]. Furthermore, since nearly two-thirds of the original oil in place (OOIP) is left unrecovered in reservoirs at the end of primary recovery and secondary waterfloods, carbon dioxide enhanced oil recovery (CO 2 -EOR) and water alternating gas (WAG) methods have attracted interest within oil companies not only as technical and profitable techniques to increase oil recovery efficiency but also as economical and ecological methods to reduce CO 2 emissions [3][4][5].…”

“…The injection targets are estimated to be at depths greater than 2000 m where pressures and temperatures can exceed 30 MPa and 373 K [2,6]. At these conditions, pure CO 2 will be in a supercritical state (T c ~ 304.13 K and P c ~ 7.38 MPa) and with densities higher than 662 kg·m -3 .…”

Effect of chemical structure of organics on pore wetting

“…It is well known that pore wetting is of significance in many practical processes, such as fuel cells, groundwater movements, material engineering, nanofluidics, nanolubrication, CO 2 storage and oil recovery (Altman et al, 2014;Bikkina, 2011;Brovchenko and Oleinikova, 2011;Chalbaud et al, 2009;Espinoza and Santamarina, 2010;Hui and Blunt, 2000;Martic et al, 2005;Raimondo et al, 2014;Saraji et al, 2013;Sghaier et al, 2006;Stukan et al, 2010;Vanzo et al, 2014). For instance, the wettability of a porous-structured oil reservoir controls how and where fluids flow and reside in the reservoir and determines the displacement efficiency for oil recovery (Ersland et al, 2010).…”