Pore-scale simulation of adaptive pumping remediation in heterogeneous porous media

Abstract

Spilled petroleum hydrocarbons pose a long-term threat to surrounding soil and groundwater, so the design of related remediation methods exhibits a growing global concern. Numerous innovative methods have been developed based on Pump-and-Treat (P&T) technology, which is the most commonly used decontamination method. Understanding the pore scale remediation mechanism of adaptive pumping is essential to the development of a decontamination scheme. In this study, the phase-field method was used to capture the evolution of the two-phase interface in a pore scale heterogeneous model during the period of adaptive pumping, and the influences of displacement patterns and wettability on remediation efficiency were investigated systematically. The results demonstrate that the model has the shortest dimensionless breakthrough time under mix-wet conditions, while it has the longest dimensionless breakthrough time under water-wet conditions. Compared with positive pumping, the growth of the ultimate remediation efficiency of adaptive pumping reaches the maximum (11.39%) under mix-wet conditions with Ca = −4.7, M = −2. The remediation mechanism of the adaptive pumping includes increasing the swept area near the boundary, extending the maintenance time of the driving pressure difference, and expanding the interfacial area between the injected fluid and the contaminant. These mechanisms indicate that a higher remediation efficiency can be obtained when adaptive pumping is applied combined with some innovative decontamination approaches, such as chemically enhanced flushing technology and in situ thermal treatment technology.