1.2 Definition of TermsThe following definitions are used in this section of the Handbook.Crude oil is a liquid hydrocarbon produced from a reservoir. Condensate is liquid hydrocarbonthat condenses from the gas as pressure and temperatures decrease when the gas isproduced from the reservoir up the tubing and out the wellhead choke. Condensate is usuallylighter in color and lower in molecular weight and viscosity than crude oil; however, a lightcrude oil could have properties similar to a condensate.Hydrocarbons are composed of many different components or molecules of carbon andhydrogen atoms. Starting with the lightest molecular weight, they are methane (CH4), ethane(C2H6), propane (C3H8), butane (C4H10), pentane (C5H12), hexane (C6H14), and so on. As theratio of carbon to hydrogen atoms increases, the molecules become heavier and have agreater tendency to exist as a liquid rather than a gas.An oilfield facility is a collection of equipment that is used to separate the fluids that comeout of an oil or gas well into separate streams that can then be sold and sent to a gas plant orrefinery for further processing.A process simulation is a calculation, usually done with a computer program that predictshow the components that make up the well fluids react to changes in pressure and temperatureas they are processed through the facility. This is not a chemical reaction, but rather a simplephase change as liquids flash to vapor or vapors condense into liquid. As the pressure is reducedor the temperature is increased, the lighter molecules, such as methane and ethane, tendto boil off into the vapor phase, taking some of the midrange components with them. The remainderof the midrange and most of the heavier molecules stabilize as liquid.Basic sediment and water (BS&W) is the percent by volume of water and solid impuritiesin the oil. Oil pipeline specifications range from 0.1 to 3%, with a typical Gulf of Mexicopipeline requirement of 1% by volume.The bubblepoint, or true vapor pressure, is the point at which gas first appears within aliquid sample as the temperature is raised or the pressure lowered. The bubblepoint of a hydrocarbonliquid is a function of pressure, temperature, and the composition of the liquid.Reid vapor pressure is the pressure at which a hydrocarbon liquid will begin to flash tovapor under specific conditions. It can be measured in the field according to a specific AmericanSociety for Testing and Materials standard and results in a pressure lower than the truevapor pressure.The hydrocarbon dewpoint is the point at which hydrocarbon liquid first condenses from agas sample when the temperature is lowered or the pressure is increased, and it depends on thecomposition of the gas. The water dewpoint is often specified for gas pipelines for hydrate andcorrosion control. Depending on the history of the hydrocarbon fluid (i.e., the processing thathas occurred upstream of the point in question), the hydrocarbon and water dewpoints may notbe the same.Hydrates are crystalline, ice-like solids that form in the presence of hydrocarbon gas andliquid water. Hydrates can form at temperatures significantly higher than the freezing point ofwater and can plug equipment and pipelines.