Natural-gas condensate

Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure. Natural-gas condensate, also called natural gas liquids, is a low-density mixture of hydrocarbon liquids that are present as gaseous components in the raw natural gas produced from many natural gas fields. Some gas species within the raw natural gas will condense to a liquid state if the temperature is reduced to below the hydrocarbon dew point temperature at a set pressure. The natural gas condensate is also called condensate, or gas condensate, or sometimes natural gasoline because it contains hydrocarbons within the gasoline boiling range, and is also referred to by the shortened name condy by many workers on gas installations. Raw natural gas may come from any one of three types of gas wells: There are many condensate sources, and each has its own unique gas condensate composition. In general, gas condensate has a specific gravity ranging from 0.5 to 0.8, and is composed of hydrocarbons such as propane, butane, pentane, hexane, etc. Natural gas compounds with more carbon atoms (e.g. pentane, or blends of butane, pentane and other hydrocarbons with additional carbon atoms) exist as liquids at ambient temperatures. Additionally, condensate may contain additional impurities such as: There are hundreds of different equipment configurations to separate natural gas condensate from a raw natural gas. The schematic flow diagram to the right depicts just one of the possible configurations. The raw natural gas feedstock from a gas well or a group of wells is cooled to lower the gas temperature to below its hydrocarbon dew point at the feedstock pressure. This condenses a large part of the gas condensate hydrocarbons. The feedstock mixture of gas, liquid condensate and water is then routed to a high pressure separator vessel where the water and the raw natural gas are separated and removed. The raw natural gas from the high pressure separator is sent to the main gas compressor. The gas condensate from the high pressure separator flows through a throttling control valve to a low pressure separator. The reduction in pressure across the control valve causes the condensate to undergo a partial vaporization referred to as flash vaporization. The raw natural gas from the low pressure separator is sent to a 'booster' compressor which raises the gas pressure and sends it through a cooler, and then to the main gas compressor. The main gas compressor raises the pressure of the gases from the high and low pressure separators to whatever pressure is required for the pipeline transportation of the gas to the raw natural gas processing plant. The main gas compressor discharge pressure will depend upon the distance to the raw natural gas processing plant and may require a multi-stage compressor. At the raw natural gas processing plant, the gas will be dehydrated and acid gases and other impurities will be removed from the gas. Then, the ethane (C2), propane (C3), butanes (C4), and pentanes (C5)—plus higher molecular weight hydrocarbons referred to as C5+—will also be removed and recovered as byproducts. The water removed from both the high and low pressure separators may need to be processed to remove hydrogen sulfide (H2S) before the water can be disposed of underground or reused in some fashion.