Application of Dielectric Measurement to Saturated Systems and Fluid Flow Through Porous Media.
Scope and Method of Study. Dielectric measuring techniques are applied to characterizing composite materials consisting of multiple phase components. To quantitatively interpret these measurements it is necessary to define a dielectric mixing law which relates the properties of the components of the heterogeneous material to the observed dielectric properties. There are a number of mixing laws cited in the literature. Using both consolidated and unconsolidated materials the most popular mixing laws have been investigated. Dielectric measurements were used to study fully and partially saturated materials. Water content of soils has been determined through empirical relationships. Properties of fluid flow through porous media and the amount of retained fluids were also studied using the dielectric techniques. The dielectric constant was determined from a measurement of the propagation time of an impulse at microwave frequency through a transmission line containing the test sample. Findings and Conclusions. There is no single mixing law applicable to the whole range of dielectric constant of saturating fluids. The variance of the mixing laws are not critically dependent on the shape or surface roughness of the matrix material. The lower degree of partial water saturation (S(,w) < 60%) can be obtained using the Effective Medium Theory (EMT) expression. Another formula (Square Root Equation (SRE)), is as accurate as EMT and has a simpler mathematical form. An average expression was developed to obtain the water content in an expeditious manner. The dielectric technique offers a new means of determining flow characteristic including the retained oil caused by water displacement, the velocity of the interface between two immiscible fluids and the effect of a miscible component in the flow. For example, the retention of crude oil in unconsolidated sand is four times more than carbon tetrachloride. Inclusion of methanol (as a miscible component) improves the removal of crude oil from the porous medium.
- Pub Date:
- Physics: Fluid and Plasma