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ESTIMATION OF FREE HYDROCARBON VOLUME FROM FLUID LEVELS IN MONITORING WELLS
Citation:
Lenhard, R. J. AND J. C. Parker. ESTIMATION OF FREE HYDROCARBON VOLUME FROM FLUID LEVELS IN MONITORING WELLS. GROUND WATER 28(1):57-67, (1990).
Impact/Purpose:
Under the assumption of local vertical equilibrium, fluid pressure distributions specified from well fluid levels in monitoring wells may be used to predict water and hydrocarbon saturation profiles given expressions for air-water-hydrocarbon saturation
Description:
Under the assumption of local vertical equilibrium, fluid pressure distributions specified from well fluid levels in monitoring wells may be used to predict water and hydrocarbon saturation profiles given expressions for air-water-hydrocarbon saturation-pressure relations. Vertical integration of the oil-saturation profile yields the actual oil volume in porous media per unit area adjacent to the well. Three-phase fluid distributions are predicted using a scaling procedure which requires knowledge of two-phase air-water saturation-pressure relations, hydrocarbon density, and hydrocarbon surface tension. Results reveal that whereas the distance above an oil-water table at which oil saturations become zero may be independent of soil type, estimated light non-aqueous phase liquid (LNAPL) volumes per unit area may differ substantially. Hence, estimates of LNAPL volume cannot be inferred from soil LNAPL thickness or well LNAPL thickness data without consideration of effects of soil properties. Furthermore, it is demonstrated that no simple linear conversion scheme can be employed to relate the height of LNAPL in a monitoring well to the LNAPL volume in porous media. Effects of grain-size distribution and well LNAPL thickness on the ration of actual LNAPL thickness in the aquifer to well LNAPL thickness are shown.
