Geological carbon sequestration, as a method of atmospheric greenhouse gas reduction, is at the technological forefront of the climate change movement. During sequestration, carbon dioxide (CO���) gas effluent is captured from coal fired power plants and is injected into a storage saline aquifer or depleted oil reservoir. In an effort to fully understand and optimize CO��� trapping efficiency, the capillary trapping mechanisms that immobilize subsurface CO��� were analyzed at the pore-scale. Pairs of proxy fluids representing the range of in situ supercritical CO��� and brine conditions were used during experimentation. The two fluids (identified as wetting and non-wetting) were imbibed and drained from a flow cell apparatus containing a sintered glass bead column. Experimental and fluid parameters, such as interfacial tension, fluid viscosities and flow rate, were altered to characterize their relative impact on capillary trapping. Computed x-ray microtomography (CMT) was used to identify immobilized CO��� (non-wetting fluid) volumes after imbibition and drainage events. CMT analyzed data suggests that capillary behavior in glass bead systems do not follow the same trends as in consolidated natural material systems. An analysis of the disconnected phases in both the initial and final flood events indicate that the final (residual) amount of trapped non-wetting phase has a strong linear dependence on the original amount of non-wetting phase (after primary imbibition), which corresponds to the amount of gas or oil present in the formation prior to CO��� injection. More importantly, the residual trapped gas was also observed to increase with increasing non-wetting fluid phase viscosity. This suggests that CO��� sequestration can be optimized in two ways: through characterization of the trapped fluid present in the formation prior to injection and through alterations to the viscosity of supercritical CO2. / Graduation date: 2013
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35359 |
| Date | 15 October 2012 |
| Creators | Harper, Elizabeth J. (Elizabeth Joy) |
| Contributors | Wildenschild, Dorthe |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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