Preliminary Study on Electrical Properties of Hydrocarbon-Contaminated Soils at an Artisanal Oil Field in Central Java, Indonesia

Abstract

Investigation on hydrocarbon-contaminated soils at artisanal or traditional oil fields is a challenging task since the choice of an appropriate non-hazardous method is a must. Currently, the ground penetrating radar (GPR) method is widely accepted to apply in such a case. In this study we propose an alternative method in analyzing hydrocarbon leakage absorbed by soil. For years, local people operate this artisanal oil field and they often pour in the unused oil waste into the ground. Discrete measurements of electrical conductivity of core samples were conducted using Decagon EM 50 instrument. The samples were taken from an artisanal oil field near a state-owned oil field located in Central Java. The hydrocarbon-contaminated soils were compared to those taken from uncontaminated soils in the same area. Depth of the coring is 70 cm and it was sampled at every 5 cm to obtain its conductivity values. The natural-uncontaminated soils showed a maximum value of 0.65 dS/cm at 22 cm deep whereas the maximum conductivity value of the contaminated soil samples is 1.4 dS/cm at 31 cm deep. The results of this study indicate that the electrical conductivity values of the contaminated soils increase in contrast to what is expected where the introduction of hydrocarbon into soil will tend to decrease its electrical conductivity value since hydrocarbon is highly resistive. These results suggest that biodegradation may have been occurring in the contaminated soils for a considerably length of time.