An Oil Spill Fate Model Including Sinking Effect

Abstract

An oil spill model, which accounts for the sinking effect, was developed. The main processes that affect the fate of oil processes that affect the fate of oil released into the environment, for the first days of the spill, are included. These are evaporation, spreading, dispersion, emulsification and sinking. Special consideration is given to the process of sinking of oil, and the conditions at which this to occurs are described. Also, the basic equations for determining the breaking of the spill in fragments, the size of this fragments, the overwash depth, the maximum sinking depth and the distribution of oil in the water column are given. The model is applied to two hypothetical spills of 1000 m3 in stratified waters. The two spills differ in the density of the oil, 900 and 990 Kg/m3. In the first case the oil disappears from the surface after seven days at sea, mostly from evaporation and dispersion, while in the second case, because the high density of the oil, the spill sinks completely after 18 hours at sea. Introduction There is a considerable interest in the development of mathematical models for the prediction of the behavior of oil spills in prediction of the behavior of oil spills in water bodies. Such models, apart from the scientific interest, are important tools for contingency planning in oil spills, environmental impact statements and spill response decision making methods. An important aspect to be considered in these models is the sinking effect, specially for heavy and high emulsified oils. Several authors have indicated the sinking of oil slicks in different situations. In Venezuela, specifically in Lake Maracaibo, oil spills have been reported to sink, the resurface after several days in some other location. These situations have produced ecological problems and hence the need to determine problems and hence the need to determine whether a specific oil spill will sink in the water column. This paper is organized in the following major sections. First, the background for the development of the model is outlined. Secondly, the main processes that control oil spills in water and the equations used in the model are described. Then, the factors that control the sinking of oil are presented, as well as the equations used in the model. Following, the computer model and two applications to simulate oil spills are described. Finally, based on the model results, conclusions are drawn regarding the fate of the oil spills and recommendations are given for future studies. Background In 1986, INTEVEP, S.A., the R and D wing of the Venezuelan Oil Industry developed an oil spill trajectory and fate model for the National Contingency Plan (NCP), which take into consideration winds and currents for the trajectory simulation, and spreading, dispersion and evaporation for the fate of the oil spill. P. 445

Response‐predictive model of oil spills in aquatic environments

“…Subsequent grid values form a decreasing function with radius and height traversed. The variation compares considerably with the trend in the experimental results of Villoria et al (1991) in which petroleum-weathering processes were considered in which the concentration of oil sunk forms a decaying function with depth. After 24 hours it is observed from results of the computer program that the oil was sunk completely since the maximum concentration was 0.0 moles per litre.…”

Property Scaling Relations for Nonpolar Hydrocarbons

“…In separation units such as distillation, adsorption, or stripping columns, surface tension is a useful parameter to determine foaming characteristics. Surface tension is also needed in the calculation of the rate of oil dispersion on a seawater surface polluted by an oil spill . The determination of surface tension by experimental techniques is time consuming, expensive, and prone to experimental and human errors during the interpretation of data.…”

Sea Surface Oil Slick Light Component Vaporization and Heavy Residue Sinking: Binary Mixture Theory and Experimental Proof of Concept

“…Wilson et al (1986) confirmed a significant increase in the density of oil may be achieved by evaporative weathering due to exposure in wind tunnels (Wilson et al, 1986). Villoria et al (1991) modeled oil sinking based on a hypothetical spill, concluding that spills with a high initial density may reach the necessary critical sinking density (Villoria et al, 1991). Extensive studies have examined the effect of environmental factors on the rates of evaporation and dissolution, and equations were developed to estimate mass transfer coefficients based on wind speed (MacKay and Yeun, 1983).…”