OGC meaning in oil and gas

Online Gas Chromatograph

An on-line analytical instrument which gives a chemical analysis of a gas, typically every 15 minutes or so, depending on the accuracy and number of components required in the analysis. Often used in gas fiscal metering stations. The analysis typically is used to calculate gas density using AGA 8 (American Gas Association) or some other algorithm as well as gas calorific value (CV). Gas transportation tariffs are usually based on exported volumes. Pipeline integrity systems are usually based on mass balances, so density is required to calculate mass from a volume meter. CV is required as usually gas contracts sell energy and not volume or mass.