HR: 1340h
AN: H13F-1659    [Abstracts]
TI: Modeling Near-Surface Carbon Dioxide Migration from a Shallow Horizontal Well
AU: * Oldenburg, C M
EM: cmoldenburg@lbl.gov
AF: Earth Sciences Division Lawrence Berkeley National Laboratory, MS 90-1116 1 Cyclotron Road, Berkeley, CA 94720, United States
AU: Dobeck, L
EM: dobeck@chemistry.montana.edu
AF: Department of Chemistry & Biochemistry, Montana State University 108 Gaines Hall, Bozeman, MT 59717, United States
AU: Spangler, L
EM: spangler@montana.edu
AF: Office of Research, Creativity, and Technology Transfer, Montana State University 207 Montana Hall, Bozeman, MT 59717, United States
AB: Simulations of CO₂ release from a 70 m-long horizontal well at a depth of 2.5 m were carried out in support of a CO₂ shallow-release experiment. The experiment was conceived by the ZERT Project to provide a facility at which researchers can develop capabilities and test approaches for monitoring potential CO₂ seepage from geologic CO₂ storage sites. The main challenge facing the monitoring community is how to detect small CO₂ seepage fluxes potentially arising from CO₂ storage sites in the presence of natural background fluxes caused by biological processes. The purpose of the simulation study was to elucidate expected migration processes arising from CO₂ release and to provide estimates of surface fluxes to aid in the design of the field experiment. Simulations were carried out using TOUGH2/EOS7CA, a module of the TOUGH2 codes for modeling subsurface migration of water, CO₂, and air. The field site is characterized by an organic-rich soil underlain at 1.2 m depth by a sandy cobble. The watertable fluctuates seasonally and was at a depth of 1.6 m during the experiment resulting in a sub-watertable CO₂ release. A shallow vertical-well CO₂ injection test was carried out to observe injectivity and surface CO₂ flux of the soil-cobble system. Accumulation chamber measurements of CO₂ flux for this test were used to calibrate the permeability and porosity of the model. Calibrated permeability of the soil was around 5 x 10 ^-11 m² (50 Darcy), suggestive of macropores caused by cracks or root casts in the soil. Use of the calibrated properties of the soil and cobble layers in the predictive simulations for the horizontal-well release of 100 kg CO₂/day for 10 days resulted in breakthrough times and average fluxes in good agreement with observations. The model shows high concentrations persist near the injection well long after the injection stops, while shallow-soil concentrations dissipate. Acknowledgment: This work was funded by the Assistant Secretary for Fossil Energy, Office of Sequestration, Hydrogen, and Clean Coal Fuels, NETL, of the U.S. Dept. of Energy under Contract No. DE-AC02-05CH11231.
DE: 1847 Modeling
DE: 1848 Monitoring networks
DE: 1899 General or miscellaneous
SC: Hydrology [H]
MN: 2007 Fall Meeting