A Coupled Hydrogeological-Petrophysical Analysis of Geophysical Variations in the Vadose Zone

Abstract

This study compares fluid content profiles derived from high-resolution geophysical data acquired before and after a controlled light non-aqueous phase liquid release experiment with those from hydrogeological models (Van Genuchten and Brooks-Corey) based on laboratory saturation-capillary pressure data for the porous medium. Standard petrophysical relationships (e.g., Archie's equation, Topp's equation and Complex Refractive Index Method) were used to convert in situ geophysical properties to fluid contents and saturations. The total fluid content profiles estimated from neutron probe data using a linear relationship is a good overall match to the hydrogeological prediction for both uncontaminated and contaminated conditions. In contrast, the water saturation and content profiles estimated from the vertical resistivity probe and time domain reflectometry data, respectively, differ appreciably from the hydrogeological model predictions of water content. Further, these differences are greater for the three-phase contaminated case. The results of this study suggest that care should be exercised when estimating fluid content from geoelectrical properties using standard petrophysical relationships. The inference of water content from geoelectrical probes therefore requires more study necessitating the development of petrophysical relationships that are applicable over a wider range of vadose zone conditions.

Meeting Name

19th Symposium on the Application of Geophysics to Engineering and Environmental Problems (2006: Apr. 2-6, Seattle, WA)

Department(s)

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Complex Refractive Index Methods; Fluid Content; Geoelectrical; Geoelectrical Properties; Geophysical Data; Geophysical Properties; High Resolution; Hydrogeological; Hydrogeological Models; In-situ; Light Non-aqueous Phase Liquids; Linear Relationships; Petrophysical Relationship; Porous Medium; Pressure Data; Release Experiments; Time Domain Reflectometry; Vadose Zone; Vertical Resistivity; Water Saturations; Groundwater; Porous Materials; Probes; Refractive Index; Geophysics

International Standard Book Number (ISBN)

978-1622760657

International Standard Serial Number (ISSN)

1554-8015

Document Type

Article - Conference proceedings

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2006 Environmental and Engineering Geophysical Society (EEGS), All rights reserved.

Publication Date

01 Apr 2006

Link to Full Text

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