EAGER: Compressibility of Nanopore-Confined Liquids Probed by Ultrasonic Experiments

点击翻译按钮获取中文摘要

Understanding how waves propagate through geological material is important because it forms the basis for creating powerful characterization tools. For example, seismic waves can be used to learn about geological formations, and ultrasonic waves can be used to analyze rock samples in the laboratory. Wave propagation speed is determined by the compressibility of the material through which it passes. Because many geological materials are porous and filled with liquids (water, brine, petroleum, etc.), wave propagation depends on the compressibilities of both the solid and liquid parts. Therefore, by knowing the individual compressibility properties one can use wave propagation to determine how much liquid is contained within the pores of a solid. However, when the pore diameters measure a few nanometers across, the liquids confined in those pores may have very different compressibility properties than in bulk. This research project aims to quantify how confinement in nanopores changes the compressibility of a range of liquids. This research will advance the understanding of wave propagation in important nanoporous media, such as hydrocarbon-bearing shale. The knowledge gained from this research could contribute towards the more efficient exploration and development of energy resources, carbon dioxide sequestration, and large-scale energy storage technologies. This research project will contribute to improved STEM education through the inclusion of research-related topics in the undergraduate courses taught at the university. During the summer months high school interns from the NJIT ACS-SEED program for economically disadvantaged high-school students will work on projects related to this research.The objective of this research project is to explore the effects of confinement on the compressibility of fluids by means of adsorption-ultrasonic experiments. When fluids are confined in nanopores, many of their physico-chemical properties change as compared to bulk. A small number of experimental studies suggest that the compressibility of fluids confined in nanopores also deviates from the compressibility of the same fluids in bulk. Modeling studies predict that the departure of compressibility progressively increases with decreasing pore size. Thus, the central hypothesis of this research project is that confinement will change the elastic properties of all fluids when the pore size is comparable to the fluid molecule size and that the extent of this change is determined by the pore size and strength of the solid-fluid interactions. This research project will test this hypothesis experimentally and explore the effects of other parameters, such as the properties of the pore surface and the structure of the fluid molecules. Experimental confirmation of a significant departure of nano-confined fluid compressibility from the corresponding bulk values has transformative potential, requiring the revision of wave propagation theory in porous media when the media are nanoporous. This research project also will promote novel interdisciplinary perspectives by connecting the studies of compressibility of confined fluids (molecular thermodynamics) to studies of wave propagation in porous media (geophysics).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.