Final Report: Molecular Mechanisms of Interfacial Reactivity in Near Surface and Extreme Geochemical Environments (DE-SC0009362)

Dixon, David A¹ 

[1] Univ. of Alabama, Tuscaloosa, AL (United States)

关键词: computational geochemistry;    CO2 sequestration;    acid-base chemistry;    uranyl chemistry;    CO2 chemistry;    MAchemistry;    solvation;   

DOI  :  10.2172/1243368
RP-ID  :  Final Report DE-SC0009362
PID  :  OSTI ID: 1243368

学科分类：地球科学(综合)

美国|英语

来源: SciTech Connect

【 摘 要 】

The prediction of the long-term stability and safety of geologic sequestration of greenhouse gases requires a detailed understanding of subsurface transport and chemical interactions between the disposed greenhouse gases and the geologic media. In this regard, mineral-fluid interactions are of prime importance since reactions that occur on or near the interface can assist in the long term sequestration of CO2 by trapping in mineral phases such as carbonates, as well as influencing the subsurface migration of the disposed fluids via creation or plugging of pores or fractures in the host rock strata. Previous research on mineral-fluid interaction for subsurface CO2 storage has focused almost entirely on the aqueous phase, i.e., reactivity with aqueous solutions or brines containing dissolved CO2. However, interactions with neat to water-saturated non-aqueous fluids are of equal if not greater importance since supercritical CO2 (scCO2) is less dense than the aqueous phase or oil which will create a buoyant scCO2 plume that ultimately will dominate the pore volume within the caprock, and the injected scCO2 will contain water soon after injection and this water can be highly reactive. Collectively, therefore, mineral interactions with water-saturated scCO2-dominated fluids are pivotal and could result in the stable sequestration of CO2 by trapping in mineral phases such as metal carbonates within otherwise permeable zones in the caprock. The primary objective is to unravel the molecular mechanisms governing the reactivity of mineral phases important in the geologic sequestration of CO2 with variably wet supercritical carbon dioxide as a function of T, P, and mineral structure using computational chemistry. This work is in close collaboration with the PNNL Geosciences effort. The focus of the work at The University of Alabama is computational studies of the formation of magnesium and calcium carbonates and oxides and their reactivity and providing computational support of the experimental efforts at PNNL, especially for energetics, structural properties, and interpretation of spectra.