A simulation study of in-situ NAPL remediation treatment by using surfactant and foam processes in a military base South Korea

Abstract

Surfactant and foam processes have been widely used to enhance oil recovery from petroleum-bearing geological formations, and also been recently extended to remediate non-aqueous-phase-liquid (NAPL) contaminants from the shallow subsurface. This study investigates the potential of using surfactant and foam processes for the in-situ remediation treatments within a military base in South Korea: first, optimizing the subsurface permeability and net-to-gross (NTG) values based on history matching and machine-learning algorithm; second, performing simulations that successfully predict the surfactant/foam processes applied in the field; and third, expanding simulations that evaluate different scenarios that might have been used for field tests.The site for the pilot-scale testing, located in the existing fuel-distribution facilities within a military base, has 5 m × 5 m treatment area with 3 m depth, prepared with 3 injection wells and 3 extraction wells. The NAPL of interest is a mixture of various oil compounds showing the average oil saturation of 5%. The overall remediation process applied consists of two major steps: the first is a 20-day injection of surfactant solution (Tween 80) to mobilize the oleic phase trapped by capillary force, and the second is a 3-day injection of foam (i.e., gas and surfactant co-injection) to control the mobility of injected gas and overcome the heterogeneity of the underground system.The major findings of this study are (i) surfactant/foam processes can be an effective means of NAPL recovery from shallow subsurface recovering more than 90% of contaminants, and (ii) computer simulations can be a useful tool for evaluating the in-situ treatment and improving the design of similar operations.