Abstract
Natural gas is considered a cleaner and lower-emission fuel than coal, and its high abundance from advanced drilling techniques has positioned natural gas as a major alternative energy source for the U.S. However, each ton of CO2 emitted from any type of fossil fuel combustion will continue to increase global atmospheric concentrations. One unique approach to reducing anthropogenic CO2 emissions involves coupling CO2 based enhanced gas recovery (EGR) operations in depleted shale gas reservoirs with long-term CO2 storage operations. In this paper, we report unique findings about the interactions between important shale minerals and sorbing gases (CH4 and CO2) and associated economic consequences. Where enhanced condensation of CO2 followed by desorption on clay surface is observed under supercritical conditions, a linear sorption profile emerges for CH4. Volumetric changes to montmorillonites occur during exposure to CO2. Theory-based simulations identify interactions with interlayer cations as energetically favorable for CO2 intercalation. In contrast, experimental evidence suggests CH4 does not occupy the interlayer and has only the propensity for surface adsorption. Mixed CH4:CO2 gas systems, where CH4 concentrations prevail, indicate preferential CO2 sorption as determined by in situ infrared spectroscopy and X-ray diffraction techniques. Collectively, these laboratory studies combined with a cost-based economic analysis provide a basis for identifying favorable CO2-EOR opportunities in previously fractured shale gas reservoirs approaching final stages of primary gas production. Moreover, utilization of site-specific laboratory measurements in reservoir simulators provides insight into optimum injection strategies for maximizing CH4/CO2 exchange rates to obtain peak natural gas production.
Original language | English |
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Pages (from-to) | 7844-7851 |
Number of pages | 8 |
Journal | Energy Procedia |
Volume | 63 |
DOIs | |
State | Published - 2014 |
Externally published | Yes |
Event | 12th International Conference on Greenhouse Gas Control Technologies, GHGT 2014 - Austin, United States Duration: Oct 5 2014 → Oct 9 2014 |
Funding
This work was funded by the U.S. Department of Energy Office of Fossil Energy Research and Office of Basic Energy Sciences, Geosciences. Instrument development was conducted under the Carbon Sequestration Initiative, a Laboratory Directed Research and Development program at Pacific Northwest National Laboratory (PNNL). Part of this work was performed at EMSL, a national scientific user facility at PNNL that is managed by the DOE’s office of Biological and Environmental Research. A portion of the simulations work was performed using PNNL's Institutional Computing (PIC) program, focused on Laboratory needs and DOE missions. PNNL is operated for DOE by Battelle Memorial Institute under Contract No. DE-AC06-76RLO-1830.
Keywords
- Carbon sequestration
- Clay minerals
- Wet supercritical carbon dioxide