Production fluid is the fluid mixture of oil, gas and water in formation fluid that flows to the surface of an oil well from a reservoir. Its consistency and composition varies. Fluids may be described by a multitude of characteristics including: Water cut - the proportion of the fluid, which is water rather than hydrocarbons. API gravity - the oilfield measurement of the weight of the hydrocarbons. GOR - Gas to oil ratio describing how many standard cubic feet of gas can be obtained for every stock tank barrel of oil. H2S - the concentration of this gas. Fluids with a high concentration of H2S are described as "sour". External links Schlumberger Oilfield Glossary: produced fluid Petroleum production Natural gas