Experimental Geochemical Studies Relevant to Carbon Sequestration
The authors are conducting laboratory studies to determine: (i) the thermophysical properties and phase relations of CO{sub 2}CH{sub 4}-H{sub 2}O fluids; (ii) the magnitude of stable isotope partitioning during calcite precipitation; and (iii) the utility of natural isotopic tracers in quantifying CO{sub 2} residence times, storage capacity and reaction mechanisms in the subsurface. The ultimate aim of the research on CO{sub 2}-CH{sub 4}H{sub 2}O fluids is to develop a comprehensive equation of state for binary and ternary mixtures of CO{sub 2}, CH{sub 4} and H{sub 2}O at pressure-temperature (P-T) conditions representative of those in deep gas fields and saline aquifers. To acquire the data needed to create the model, two unique, custom-designed devices at the Oak Ridge National Laboratory--a high pressure vibrating-tube densimeter, and a hydrogen-service internally heated pressure vessel--are being used to measure the densities, excess molar volumes, miscibility limits and activity-composition relations of CO{sub 2}H{sub 2}O, CH{sub 4}-H{sub 2}O and ternary CO{sub 2}-CH{sub 4}-H{sub 2}O mixtures at P-T conditions near the vapor-saturation phase boundary in the H{sub 2}O system. In another project, experiments are being conducted to determine the kinetics of carbonate precipitation from CO{sub 2}-rich saline waters, and associated isotope partitioning. Both inorganic and microbially mediated processes are being investigated under environmental conditions encountered during CO{sub 2} injection into the subsurface. Our results indicate that the behavior of isotopes, especially oxygen isotopes, is affected by the composition of water and the precipitation rate of carbonate minerals. We have also observed significant carbon isotope partitioning (4 to 8{per_thousand}) between CO{sub 2} and hydrocarbon-saturated rock (an EOR injection scenario) reacted statically at 25 C. These preliminary results suggest that a light isotopic component of CO{sub 2} may be retained in the reservoir, leading to isotopically heavier CO, further down the flow path.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- AC05-96OR22464
- OSTI ID:
- 774468
- Report Number(s):
- P00-109112; TRN: AH200109%%118
- Resource Relation:
- Conference: First National Conference on Carbon Sequestration, Washington, DC (US), 05/15/2001--05/17/2001; Other Information: PBD: 10 Jan 2001
- Country of Publication:
- United States
- Language:
- English
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