Optimizing separate phase light hydrocarbon recovery from contaminated unconfined aquifers

Authors

G. S. Cooper
Richard C. Peralta, Utah State UniversityFollow
Jagath J. Kaluarachchi, Utah State UniversityFollow

Document Type

Article

Journal/Book Title/Conference

Advances in Water Resources

Volume

21

Issue

5

Publication Date

4-15-1998

First Page

339

Last Page

350

Abstract

A modeling approach is presented that optimizes separate phase recovery of light non-aqueous phase liquids (LNAPL) for a single dual-extraction well in a homogeneous, isotropic unconfined aquifer. A simulation/regression/optimization (S/R/O) model is developed to predict, analyze, and optimize the oil recovery process. The approach combines detailed simulation, nonlinear regression, and optimization. The S/R/O model utilizes nonlinear regression equations describing system response to time-varying water pumping and oil skimming. Regression equations are developed for residual oil volume and free oil volume. The S/R/O model determines optimized time-varying (stepwise) pumping rates which minimize residual oil volume and maximize free oil recovery while causing free oil volume to decrease a specified amount. This S/R/O modeling approach implicitly immobilizes the free product plume by reversing the water table gradient while achieving containment. Application to a simple representative problem illustrates the S/R/O model utility for problem analysis and remediation design. When compared with the best steady pumping strategies, the optimal stepwise pumping strategy improves free oil recovery by 11.5% and reduces the amount of residual oil left in the system due to pumping by 15%. The S/R/O model approach offers promise for enhancing the design of free phase LNAPL recovery systems and to help in making cost-effective operation and management decisions for hydrogeologists, engineers, and regulators.

Recommended Citation

Cooper, G. S.; Peralta, Richard C.; and Kaluarachchi, Jagath J., "Optimizing separate phase light hydrocarbon recovery from contaminated unconfined aquifers" (1998). Civil and Environmental Engineering Faculty Publications. Paper 1459.
https://digitalcommons.usu.edu/cee_facpub/1459