Mechanisms of acoustic stimulation of fluid flow in porous media: Integration of laboratory pore-scale studies and theoretical model development

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O125214BeresnevTwo pervasive practical problems are related to the reduced mobility of organic fluids in porous media: the difficulty in removing organic contaminants from groundwater and incomplete petroleum recovery from reservoirs. The existing solutions are expensive and often ecologically hazardous. On the other hand, the flow of pore fluids can be significantly enhanced by the application of elastic waves. The sonic stimulation is ecologically clean and economical. The proliferation of sonic-stimulation technologies has been hampered by inadequate understanding of the mechanisms by which the elastic waves mobilize pore fluids . A theory of sonic stimulation virtually does not exist. The proposing team at Iowa State University aims at gaining insight into quantitative physical mechanisms of stimulation and building a mathematical model of key phenomena in play.To study the microscopic mechanisms of fluid-sound interaction, the investigators will use the pore-scale flow visualization apparatus developed at the Department of Chemical Engineering. The unit matches the refractive index of all phases in a porous cell to make it transparent to light. A fluorescent dye is added to the organic fluid to make it the only one visible when illuminated by a laser source; the two-dimensional images are captured by a digital camera and then combined in a three-dimensional rendering of the system. The unit allows direct observation of the movement of organic ganglia subjected to sonic forcing. These investigations will be combined with the development of a theoretical and numerical model of sonic stimulation at the Department of Geological and Atmospheric Sciences. Among the mechanisms to include is the peristaltic motion, the effects of mechanical vibrations on capillary forces, coalescence of ganglia, and the boundary-film effects. The theoretical analyses will use the multi-phase continuum approach (Navier-Stokes equations) and the Monte-Carlo (pore-network) simulations.By integrating the theory development with the pore-scale investigations, a working model of the sonic stimulation will be built. This model will serve the basis for the applications of the new technology to environmental restoration and enhanced oil recovery.