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Abstract: Factors Affecting Recovery of Free Product from a Shallow Water Table

Harding Lawson Associates, Pittsburgh, PA

When a new petroleum reservoir is discovered, the initial concerns of the petroleum geologist might be; how much hydrocarbon is present and what portion of the total quantity can be recovered. Similarly, when floating free (i.e. separate) phase hydrocarbon is discovered on a shallow water table, the environmental geologist is concerned with determining the quantity present and how to maximize recovery. While recovery of 30% of the total quantity of crude oil in a reservoir may be sufficient to permit development of the field, the portion of the total quantity of freephase hydrocarbon that must eventually be recovered in an environmental project theoretically approaches 100%. Typically, the environmental geologist is concerned with the efficiency of recovery because pumping strategies are usually the first techniques to be employed in the remediation of a site where free-phase hydrocarbons have been released to the water table.

This paper provides a summary of some of the techniques used to estimate the quantity and recovery efficiencies associated with removal of spilled free-phase hydrocarbons from a shallow water table. Factors that affect the estimation of the quantity of recoverable hydrocarbon and some of the fallacies of estimating total quantity of free phase hydrocarbon are described. Results of implementing various recovery techniques at sites with shallow water tables are provided. These results give insights to developing a successful free-phase hydrocarbon recovery strategy for sites with a shallow water.

AAPG Search and Discovery Article #90930©1998 AAPG Eastern Section, Columbus, Ohio