Time-domain transient electromagnetic (TDEM) soundings in the vicinity of a refinery in Saratov city, Russia, aimed at detecting oil contamination of groundwater and tracing pollution flows in drainage zones. Hydrocarbons in rocks are detected from high electrical resistivity and induced polarization (IP) effects observed in many TDEM curves. Polarizability (η) is found as a ratio of the excess electrolytic conductivity of pore fluids to their natural conductivity. IP relaxation time (τ) is found to depend mainly on radius of pores in water-saturated sediments. IP effects can be revealed by TDEM soundings in wet sediments with imperfect phase binds and the radius of pores from 10–4 to 5⋅10−6 m. Interpretation of the TDEM data by the method of “sliding plane” (Sτ version) and mathematical modeling allowed us to detect oil-contaminated layers with polarizability between 20 and 30% and a time constant of 1.8⋅10−4 s. The surface of the polluted groundwater plume roughly follows the topography of the underlying Cretaceous sediments (Albian clays). The plume is located below the groundwater table in the region of the thickest Quaternary sands. The buried surfaces of Albian clays may act as temporal traps of hydrocarbons drained with groundwater from surface industrial wastes.

You do not have access to this content, please speak to your institutional administrator if you feel you should have access.