HR: 11:55h
AN: H22B-07    [Abstracts]
TI: Elastic Waves Push Residual Organic Fluids From Saturated Rock
AU: * Beresnev, I A
EM: beresnev@iastate.edu
AF: Department of Geological and Atmospheric Sciences, Iowa State University, 253 Science I, Ames, IA 50011-3212 United States
AU: Vigil, R D
EM: vigil@iastate.edu
AF: Department of Chemical Engineering, Iowa State University, 2114 Sweeney Hall, Ames, IA 50011-2230 United States
AU: Li, W
EM: wenqing@iastate.edu
AF: Department of Chemical Engineering, Iowa State University, 2114 Sweeney Hall, Ames, IA 50011-2230 United States
AB: With world oil reserves dwindling and production shifting to increasingly forbidding environments, the emphasis is greater than ever on the more efficient extraction of the existing oil. Yet typically up to two-thirds of the U. S. domestic oil is abandoned underground. Elastic waves have been observed to increase productivity of oil wells, although the reason for the vibratory motion mobilizing the residual organic fluids has remained unclear. Residual oil is entrapped as blobs or ganglia in narrow pore constrictions due to the resisting capillary forces that prevent free motion of non-wetting fluids driven by water. A finite external pressure gradient, exceeding an "unplugging" threshold, is needed to carry the residual ganglia through. We show that vibrations help overcome the resistance of capillary forces by adding an oscillatory inertial forcing to the external gradient; when the vibratory forcing acts along the gradient and the threshold is exceeded, instant "unplugging" occurs. This mechanism predicts the mobilization effect to be proportional to the amplitude and inversely proportional to the frequency of vibrations. We observe this dependence in a laboratory experiment, in which residual saturation of an organic fluid is created in a glass micromodel, and mobilization of the dyed ganglia is monitored using digital photography. We also directly demonstrate the release of an entrapped ganglion from a pore constriction by the application of vibrations in a computational fluid-dynamics simulation. The technologies that can utilize this phenomenon are not limited to enhanced oil recovery, but also apply to the remediation of groundwater contaminated by leaks from underground storage tanks and surface spills of organic fluids.
DE: 5139 Transport properties
DE: 1832 Groundwater transport
DE: 1894 Instruments and techniques
DE: 0935 Seismic methods (3025)
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting