Stock tank vapor is the gaseous phase that separates from crude oil when it is brought to surface conditions, typically at standard temperature and pressure (e.g., 60°F and 14.7 psia), in a stock tank or separator. During oil production, reservoir fluids, which exist under high pressure and temperature, contain dissolved gases. When these fluids are brought to the surface, the reduction in pressure and temperature causes the lighter hydrocarbon components to vaporize and separate from the liquid oil. This vapor, known as stock tank vapor, consists primarily of volatile hydrocarbons like methane, ethane, propane, and butane, along with other gases such as carbon dioxide or nitrogen, depending on the reservoir composition. These vapors are significant in the oil and gas industry because they impact the volume and quality of the produced oil, contribute to emissions, and can be captured for further processing or use, such as in gas recovery systems or for energy production.
