The Effect Of Ultrasonic Energy On The Flow Of Fluids In Porous Media
Authors: Duhon Rex D. , Campbell John M. 
Published: December 2007

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Abstract
This paper summarizes the results of a preliminary investigation into the possible utilization of ultrasonics to promote the flow of fluids in porous media. The work reported is in essence a feasibility study of the ability of such waves to impart useful energy to a fluid-filled porous media, particularly for the case where one such fluid is being displaced by another. Also considered has been the possibility of selectively rejecting fluids in selected open-hole intervals by means of "focused" ultrasonic waves.
A series of controlled tests was made on a sixteen-inch diameter by 1.82-in. thick piece of torpedo sandstone using diesel oil, SAE 10 oil and core test fluid as the hydrocarbons. These fluids were displaced by saline water in a series of "flood tests" designed to characterize the behavior of the system with and without the addition of sonic energy. The results of these tests [shown herein] serve to show that the addition of sonic energy increases displacement efficiency. Several reasons are hypothesized for this result. It is likewise indicated that the desired selective injectivity was feasible.
Although the results of these experiments cannot be directly translated to field practice they serve as a basis for future studies.

Introduction
The presence of a medium is essential to the transmission of ultrasonic waves. Any material that has elasticity can propagate these waves. The propagation takes the form of a displacement of successive elements of the medium. Since all such media possess inertia, the particle continues to move after it returns to the position from which it started and finally reaches another, different, position, past the original one. From this second point it returns to its original position, about which it continues to oscillate with constantly diminishing amplitude. The elements of material will therefore execute different movements or orbits as the wave passes through them. It is the differences in these movements which characterize basic types of ultrasonic waves, but no matter what the wave type, the general properties of ultrasonics remain the same. As the wave travels through the material, successive elements in the material experience these displacements, each such element in the wave path moving a little later than its neighbor. In other words, the phase of the wave, or vibration, changes along the path of wave transmission.