The Effect of Oil Contamination on some Geotechnical Properties of West Qurna Oilfield Soils at Basrah, Southern Iraq

Ahmed K Al-Nimah

doi:10.46717/igj.54.2b.7ms-2021-08-27

Abstract

Oil contamination in soils causes several geotechnical problems that must be considered during construction. The contamination occurs due to oil seepage which could happen during oil explorations and production processes or oil transportation. The site of West Qurna oilfield in Basrah was selected for this study because it has witnessed oil seepages many times. In order to study the significant impact on geotechnical properties of soils in the West Qurna site, as uncontaminated bulk soil sample was taken at a depth of 1 m, and crude oil was added at weight ratios of 2, 4, 6, 8, and 10 %. Laboratory tests were performed on all samples; these tests included particle size distribution, moisture content, Atterberg’s limits, consolidation, unconfined compressive strength, and water absorption. The results show that soil at the West Qurna site is clayey silt with little sand and the moisture content is 29.21%. The values of liquid limit and plasticity index were gradually decreased, while the plastic limit was increased with increasing of crude oil in the soil of study. There was an increase in consolidation coefficients [compressive index, swelling index, pre-consolidation pressure, and coefficient of consolidation] with an increase in the percentages of crude oil in the soil. The results also show that there was a decrease in the values of unconfined compressive strength and absorption of water as the crude oil was increased in the soil.

Highlights

Oil contamination is one of the most dangerous pollutants that caused problems in the ecosystem (Awadh, 2015)
The results show that the viscosity is 91.84 cp at 40 oC, API is 25.5, density is 0.9126 g/cm3 at 40 oC and the specific gravity is 0.9142.The bulk sample was divided into 26 samples to use them in geotechnical tests as follow: a- Particle size distribution: This test was performed using dry sieving and hydrometer method on the soil sample in accordance to ASTM D-421, D-422
According to the result of the geotechnical properties of the soil study, the following conclusions can be drawn: The soil in the site at West Qurna oilfield is classify as clayey silt with little sand

Summary

Introduction

Oil contamination is one of the most dangerous pollutants that caused problems in the ecosystem (Awadh, 2015). Contamination affects the geotechnical properties of the soil, such as strength, permeability, porosity, and bearing capacity, which makes it unsuitable for engineering use (Breivik and Burgess, 2013). The great problem is when the effects of contamination reach the bearing strata of the foundation, causing a decrease in its strength and deformations of the foundation, which may cause a collapse of the building (Sanjay et al, 2003). Basrah is characterized by abundant of oil production (Awadeesian et al, 2018; Al-Mimar et al, 2018; Awadh et al, 2019).

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Conclusion