Quantitative Characterization of the Vibratory Enhancement of Organic-Fluid Flow in Porous Media: Integrated Experimental and Theoretical Approach

Iowa State University, Ames IA

Investigators

Abstract

The efficiency of petroleum recovery and groundwater remediation is limited by the resistive capillary forces that cause the entrapment of organic fluids in pores. Elastic waves have been observed to increase the fluid extraction, although no satisfactory explanation of this phenomenon has been given. The lack of physical understanding has hindered the development of field technologies of reservoir and aquifer stimulation. The physics of the vibratory liberation of NAPLs (non-aqueous-phase liquids) has been elucidated in an NSF project completed recently by the PIs. This mechanism describes how vibrations "nudge" the entrapped ganglia over the capillary barrier until they are released. The corollaries of the mechanism have been validated in a specially designed laboratory experiment. The formulation of the liberation mechanism paves the way for the development of a predictive model of NAPL removal by vibrations in porous networks with realistic geometries. Developing such a quantitative model, building on the current understanding of the underlying pore-scale process, is the goal of the project. This goal will be achieved through meeting three specific objectives, representing an integrated experimental, theoretical, and numerical approach. Objective 1. Developing analytical tools for the accurate analysis of the dynamics of ganglion liberation, at a pore level, by vibrations, describing the phenomenon's dependence on various parameters. This work will express the balance of forces exerted upon a ganglion in equations allowing physically transparent solutions. Objective 2. "Upscaling" the process's numerical model to 2D porous domains as a key improvement over simple 1D capillary tubes, with the use of computational fluid dynamics. The similarities and differences in the physics of the mobilization between 1D tubes and higher dimensions, in view of the added pore-connectivity and multiple-menisci geometries, will be illuminated. Objective 3. Conducting comprehensive flat-micromodel laboratory experiments to document the vibratory-stimulation process, focused on both the behavior of individual entrapped ganglia and bulk-flow enhancement. Observing and verifying the underlying pore-scale process and interactions in the dispersed organic phase, including possible break-up and coalescence. Special attention will be given to verifying the agreement between the theoretical models and observations. The possibility of predicting the vibratory-stimulation results with their physical understanding achieved, at both individual-blob and bulk-flow levels, will be tested. Intellectual Merit: The project speaks to a challenging practical need of high significance to society, at the basic-physics level. The PIs have recently completed an NSF-funded effort, in which novel ideas on the underlying mechanism of the vibratory enhancement of NAPL flow have been developed and published. The PIs have demonstrated a clear benefit of the cross-disciplinary, collaborative approach that their team represents. The new goal has evolved as a result of the previous effort, and the new phase will start on the base of knowledge that the PIs have created. Broader Impacts: Both fundamental science of capillarity and the technologies based on it will benefit from the results. The outcomes will be of immediate interest to a range of scientific disciplines dealing with elastic waves, multi-phase flow, and porous media. The PIs' previous NSF project has educated two young Ph. D. scholars, one in geophysics and one in chemical engineering. This education impact will continue. Both PIs Beresnev and Vigil teach undergraduate courses in their respective disciplines of applied geophysics and chemical engineering, in which the results have been fully integrated. The experimental infrastructure created has already benefited undergraduate education in the Chemical Engineering Department.