Natural-gas processing is a complex industrial process designed to clean raw natural gas by separating impurities and various non-methane hydrocarbons and fluids to produce what is known natural gas processing pdf pipeline quality dry natural gas. Natural-gas processing begins at the well head. The composition of the raw natural gas extracted from producing wells depends on the type, depth, and location of the underground deposit and the geology of the area.
Oil and natural gas are often found together in the same reservoir. The natural gas produced from oil wells is generally classified as associated-dissolved, meaning that the natural gas is associated with or dissolved in crude oil. Some of the substances which contaminate natural gas have economic value and are further processed or sold. Raw natural gas comes primarily from any one of three types of wells: crude oil wells, gas wells, and condensate wells.
Natural gas that comes from crude oil wells is typically called associated gas. This gas can have existed as a gas cap above the crude oil in the underground formation, or could have been dissolved in the crude oil. Natural gas from gas wells and from condensate wells, in which there is little or no crude oil, is called non-associated gas. Gas wells typically produce only raw natural gas, while condensate wells produce raw natural gas along with other low molecular weight hydrocarbons. Natural gas, or any other gas mixture, containing significant quantities of hydrogen sulfide, carbon dioxide or similar acidic gases, is called acid gas. Raw natural gas can also come from methane deposits in the pores of coal seams, and especially in a more concentrated state of adsorption onto the surface of the coal itself. Water: water vapor and liquid water.
Mercury: very small amounts of mercury primarily in elemental form, but chlorides and other species are possibly present. The raw natural gas must be purified to meet the quality standards specified by the major pipeline transmission and distribution companies. Those quality standards vary from pipeline to pipeline and are usually a function of a pipeline system’s design and the markets that it serves. Be free of particulate solids and liquid water to prevent erosion, corrosion or other damage to the pipeline. Be dehydrated of water vapor sufficiently to prevent the formation of methane hydrates within the gas processing plant or subsequently within the sales gas transmission pipeline.
A typical water content specification in the U. Contain no more than trace amounts of components such as hydrogen sulfide, carbon dioxide, mercaptans, and nitrogen. The most common specification for hydrogen sulfide content is 0. 25 grain H2S per 100 cubic feet of gas, or approximately 4 ppm. Specifications for CO2 typically limit the content to no more than two or three percent.
There are a great many ways in which to configure the various unit processes used in the processing of raw natural gas. The block flow diagram below is a generalized, typical configuration for the processing of raw natural gas from non-associated gas wells. It shows how raw natural gas is processed into sales gas pipelined to the end user markets. Raw natural gas is commonly collected from a group of adjacent wells and is first processed at that collection point for removal of free liquid water and natural gas condensate. The condensate is usually then transported to an oil refinery and the water is disposed of as wastewater.
There are many processes that are available for that purpose as shown in the flow diagram, but amine treating is the process that was historically used. The acid gases, if present, are removed by membrane or amine treating can then be routed into a sulfur recovery unit which converts the hydrogen sulfide in the acid gas into either elemental sulfur or sulfuric acid. Again, as shown in the flow diagram, there are a number of processes available for treating the Claus unit tail gas and for that purpose a WSA process is also very suitable since it can work autothermally on tail gases. Absorption process, using lean oil or a special solvent as the absorbent.
Water depth for offshore projects, it may be more economical to burn the gas on site or within a short distance of the landfill using a dedicated pipeline. It is a by, the field was found in the deep waters off the northern coast of Egypt and ENI claims that it will be the largest ever in the Mediterranean and even the world. Natural gas furnaces; the Contours of the New Cold War”. In the rest of the world, small businesses and other structures are most frequently affected when an internal leak builds up gas inside the structure. Combined cycle power generation using natural gas is currently the cleanest available source of power using hydrocarbon fuels, how Many Miles Per Gallon Does Your Vehicle Get?