CEE 281 Special Topics Report: Electrically Stimulated Recovery of Oil from Clay Rich Formations

Virginia Nyikadzino


This paper seeks to present and explain the observations and the results of a set of two experiments EK1 and EK 2, which were carried out to investigate the electrokinetic behavior of two clay soil cells that were purposely contaminated by refrigeration oil and natural oil respectively. Both soil formations were made from mixtures of clay silt and sand in the ratio of 2:2:6; however EK1 cell was measured to have 19% initial oil content, while EK2 was measured to have an initial oil content of 10.5%. These cells were subjected to a voltage gradient of 1.5 V/cm for 25 hours under recorded electrolyte pH and conductivity conditions.

The motive of this study was to investigate and quantify how well oil could be extracted from clay formations by electrokinetic methods. This information was derived from gravimetric analyses and presented in charts, but in addition other non gravimetric parameter data were also recorded, presented and discussed. These other parameters are pH, conductivity, current, voltage gradient, and flow rates, and they serve to indicate how much of the anticipated processes were occurring (current and flow), and what their effect on the soil’s water content was, from the anode to the cathode.

The results show that significant amounts of oil (up to 50%) were removed from clay by the electrokinetic processes, as predicted by available literature; such as compiled by Environmental Protection Agency/Office of Radiation and Indoor Air/Center for Remediation Technology and Tools (EPA/ORIA/CRTT) in their resource guide- this guide lists all electrokinetic processes used on a patented, bench, pilot, field or conceptual scale from the period 1992 to 1997.1

The highest success rate was in the first experiment (refrigeration oil), which produced soil samples that contained an average of 12% less oil than the initial 19%, while the second experiment (natural oil) yielded an average of about 5% less oil content compared with the initial 10.5%. These results were obtained from gravimetric analysis.

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