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

No abstract

Orimulsion is a bitumen-water mixture (approximately 70% bitumen and 30% water, with 0.2% surfactant) produced in Venezuela and sold internationally as a fuel to fire power plants. The permitting process for the introduction of this fuel into the international energy market has required extensive research and testing on its chemical composition, physical properties, behavior in water, environmental toxicity, and containment and recovery after a spill. Both components (water and bitumen) initially disperse in water. The volatile compounds, which are relatively low in concentration, are contained mostly in the water component. The bitumen is relatively inert. The density of the bitumen tends to cause it to sink in fresh water and rise in saltwater. In addition, seawater causes the emulsifier to destabilize from the bitumen. The result is that, at sea, in calm conditions with sufficient concentration, the bitumen will tend to coalesce and rise to the surface. Bitor and potential users of Orimulsion have been developing response strategies and tools for responding to Orimulsion spills. Recent field testing has shown that a spill of Orimulsion can be cleaned up using currently available response equipment in response strategies developed uniquely for Orimulsion. The tests have shown that, once contained, bitumen can be recovered from an Orimulsion spill very effectively (80% to 90% recovery).

No abstract

In November 1993, the first drill of the Venezuelan national oil spill contingency plan (VNCP) was carried out to evaluate both the response capability of the plan to cope with an emergency and the effectiveness of the regional response organization to manage the given scenario. During four days of intensive work, 800 participants, evaluators, and controllers of the drill made decisions and took actions to mobilize resources and pollution countermeasure equipment for cleanup operations. To measure the effectiveness of the response actions, 23 oil spill response processes were evaluated based on flow charts or decision trees designed for each process. In summary, the drill covered all areas related to response actions in the case of an oil spill (alert, notification, evaluation, decision-making, mobilization, field response, and postmortem), evaluating the ability of the VNCP to cope with a major emergency and identifying weaknesses in order to improve the response capability.