GLOSSARY OF OILPATCH TERMS
| Vacuum Distillation |
| The distillation of the heavier fractions of crude oil at pressure lower than atmospheric. When residuum is fractionated under a vacuum, a distillation called vacuum gas-oil is recovered. This product can undergo thermal cracking to produce additional gasoline. |
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| Visbreaking |
| A mild form of thermal cracking used in petroleum refining, primarily to improve certain fuel oil characteristics of residuum. |
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| Viscosity |
| The internal resistance to flow exhibited by a liquid, expressed numerically by a number of methods. These numerical scales, which differ widely, serve to quantify the amount of time required for a given product to flow at a fixed temperature through a standard orifice. Petroleum viscosity values are usually expressed in Saybolt Seconds Furol (SSF) and Saybolt Seconds Universal (SSU). Also used widely, though less common than the above, are the Kinematic, Engler and Redwood scales. |
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| Vug |
| A cavity in a rock. |
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