Role of Evaporation in Degrading the "Oil Lakes"

Ahamad Ahamad

doi:10.3844/ajessp.2011.219.223

Abstract

Problem statement: Oil Spills are degraded by aerobic bacteria, water washing, evaporation and oxidation. In the absence of water the first two of these processes cannot operate. Th is is the situation in the low rainfall environment of the Kuwaiti desert where oil lakes still persist 2 0 years after the initial spills. The oils contain lo nger chain n-alkanes but have lost light ends and evaporation appears to be the dominant degradation mechanism. Approach: We have simulated evaporation of Kuwaiti oil (from Burgan field) at t emperatures from 20-50°C and at various air flow rates. Results: Compositional changes monitored by gas chromatography show losses of volatile components (<C8), including alkanes, aromatics and naphthenes. Normal alkanes are lost more rapidly than other hydrocarbon types with the same carbon n umbers. Conclusion: Evaporation increases viscosity and density leading to compositional stra tification. It seems likely that a devolatilized s kin forms, protecting the underlying oil and decreasing the rate of evaporation. Oils degraded by evaporation show final compositions similar to thos e observed in the residual oil lakes.

Highlights

As a consequence of the 1991 Iraqi invasion of Kuwait considerable quantities of Oil were spilled in the desert
Compositional changes during evaporation: Based on the results of the weight loss studies, airflow rates were kept constant at 1000 round/min for the determination of compositional changes and temperature controlled at 20, 30, 40, or 50°C
100 up oil samples were removed at intervals with a hypodermic syringe, diluted 2:1 with ethylene chloride and analyzed gas chromatographically

Summary

Introduction

As a consequence of the 1991 Iraqi invasion of Kuwait considerable quantities of Oil were spilled in the desert. A typical Example for the Burgan crude oil (Fig. 4) shows this initial rapid weight loss and the subsequent decrease with time. Compositional changes during evaporation: Based on the results of the weight loss studies, airflow rates were kept constant at 1000 round/min for the determination of compositional changes and temperature controlled at 20, 30, 40, or 50°C.

Results

Conclusion