Radio frequency (RF) heating is recognized as a technique having the potential to thermally enhance remediation of hydrocarbon-impacted soil. RF heating delivers electromagnetic (EM) power to a targeted body of soil, resulting in an increased soil temperature that enhances the in-situ remediation processes such as biodegradation. Antennas are placed either on the ground or installed in the soil near the ground surface. The antennas operate in the hundreds of kHz to MHz range.
To model the RF heating process, we successfully coupled a reservoir simulator with a 3-dimensional (3D) EM solver to evaluate the ability of RF technology to heat soil in situ. The coupled reservoir/EM simulator solves the EM fields and associated heating for a heterogeneous reservoir or soil volume in the presence of multiple antennas. The coupling was accomplished through a flexible interface in the reservoir simulator that allows the runtime loading of third-party software libraries with additional physics. This coupled workflow had been previously used for studying RF heating for heavy oil recovery (Li 2019).
An RF heating simulation case study was performed in support of a soil remediation field test designed to demonstrate the ability to heat soils using EM energy. The study included field test data analysis, simulation model building, and history matching the model to test data. Results indicate, on average, the soil was heated ∼2-3°C above the initial formation temperature after approximately two days (52 hours) of RF heating. We found that the RF heating was local, and our simulation model, after tuning input parameters, was able to predict a temperature profile consistent with the field test observations. With properly designed RF heating field pilots and tuning of EM and reservoir parameters in simulation models, the coupled reservoir/EM simulator is a powerful tool for the calibration, evaluation, and optimization of RF heating operations.