Effect of Crude oil Contamination on the Geotechnical Properties of Soft Clay Soils of Niger Delta Region of Nigeria.

Abstract

This paper presents the results of recent study on the effect of crude oil contamination on the geotechnical properties of soft clay soils of Niger Delta region of Nigeria. Laboratory investigation was carried out to compare selected engineering properties of uncontaminated and oil-contaminated soft clays. The effect of contamination by crude oils from three oilfields on the engineering properties of soft clay soils has been studied. Crude oil was chosen as the contaminant. Soil samples around three oilfields as well as crude oil samples from selected oil wells in these fields were randomly collected and investigated. The oil wells are located in Bonny, Brass River and Qua-Ibo communities respectively. A comprehensive laboratory investigation was carried out on the collected samples at the field dry density of 14 kN/m3. Contamination of soft clays by crude oil caused 17.9% increase in the Liquid limit, 6.9% increase in Plastic limit and 37.5% increase in plasticity index. It also showed corresponding increase in Bulk Density with increase in sorption time. However, porosity and swelling pressure of contaminated clay decrease with increase in both sorption time and crude oil content, while its undrained shear strength fluctuates.