Abstract

Natural degradation of crude oil is very slow and might take several years to be degraded. However, its impact on the environment will last as long as neither treatment nor solutions are undertaken. When further migration of crude oil is occurring, it will harm the soil and might contact the subsurface water or groundwater. The most relevant in that respect would be the type of fluids (Contaminants), mode of fluid transport, type of soil, environmental importance of the concerned sites, and weathering effect. Therefore, the main objectives of this study are investigation and observation of crude oil migration as toxic fluid, its penetration, and weathering effect.

Achievement of the abovementioned objectives necessitates the design of an experimental model. This model consists of two separated columns, which were filled with soil and other types of rocks. One setup column contains soil in dry condition (dry system); while the other was filled with soil material in wet conditions (wet system).

During its progress, crude oil penetration was recorded versus time by taking soil samples, whereas water samples were collected from the wet system. This was aimed to report a possible migration of hydrocarbons dissolved in water.

Results show that the penetration depth was more performed in wet system during early stages rather than in dry system. However, with time this progress becomes more developed in both systems. Based on observation, it is important to notify that the duration of this progress will last for long time in dry system. However, the overall penetration at final stage has been found significantly higher in the dry system. In addition, it was observed that during crude oil migration in dry system, chromatographic separation of crude oil components has occurred obviously.

The obtained results reveal that immediate treatment action has to be performed in both systems with particular attention to the wet system, owing to its high initial penetration rate.

Introduction

Contamination of aquifers and soil by crude oil or its products can creates a massive damage to principally fresh water, and therefore the remediation becomes extremely expensive (Delin, 1998, Deonarine, 2001).

The petroleum exploration, production, transportation and other industrial branches have the potential to affect the environment in different degrees. Leakages from pipelines, stranded oil spills, overflows at gathering stations, improper disposal of petroleum wastes and leakage from underground storage tanks are the major sources of oil-contamination of surface and groundwater. When the toxic fluids contamination occurs in the soil, it can affect the structure at various degrees. The affected portion of soil must be treated to prevent subsequent pollution of surface water and groundwater. Thus, some of oil components or other toxic fluids can carry on migrating for long time before reaching the aquifer and causing pollution. The infiltration of toxic fluids into the subsurface occurs through path channels, cracks and veins. Toxic fluid circulation and further effect are also depending on the soil depth as well as the distance to the aquifer zone. Investigation of these consequences will be based on chemical reaction, transport and contamination impact. These factors constitute the main concern problem in this project. Therefore, typical contamination at the surface can be divided into various parts:

  • Portion of dissolved toxic fluids in mobile or immobile water (connate water) located at the upper vadose zone or near surface zone, may found their pathway into the groundwater surface zone, since the fluid movement depends also on soil saturation.

  • Toxic fluids may remain in the soil pores as residual saturation. They may act as a permanent source of contamination for potential feeding of the ground,

  • Some fractions of the toxic fluids may evaporate into the air or biodegradation may occur (Broje, 2007, Revill, 2007).

This content is only available via PDF.
You can access this article if you purchase or spend a download.