Oil Spill Volume Estimation introduces techniques for estimating the volume of an accidental oil spill. Determining the volume of accidental hydrocarbon discharge is rapidly becoming one of the most important aspects of maintaining an environmentally sound offshore production operation. Reporting the amount of accidentally-released oil in the environment during day-to-day operations a legal requirement in most countries has proven to be a major problem due to the non-intuitive manner in which hydrocarbons disperse over a body of water. By using color photographs of actual spills, this course trains operations personnel to correctly estimate the size of an oil spill. The photographs used in this module are part of the comprehensive archives of the International Tanker Owners Pollution Federation ITOPF in London, and have been carefully categorized by the volume per unit area they represent. A systematic method of estimating the size of a spill is presented here in a clear, step-by-step set of procedures that can be used by field operators with no previous experience. A working knowledge of these techniques is also valuable for personnel in administrative and support roles, who may have to deal indirectly with the consequences of an accidental oil spill.