Liquid mixtures of hydrocarbons (they all differ in different molecular structures and boil at high temperature), which are released as a by-product in gas condensate, gas and oil fields, are united by a common name - gas condensates. Their composition and quantity depend on the place and production conditions, therefore, they vary widely. However, they can be divided into two types:
- stable gas condensate in the form of gasoline-kerosene fractions (and sometimes higher molecular weight liquid oil components),
- unstable product, which, in addition to hydrocarbons C5 and higher, includes gaseous hydrocarbons in the form of a methane-butane fraction.
Condensate can come from three types of wells where it is produced:
- Crude oil (it comes in the form of associated gas, which can lie underground separately from crude oil (in layers) or be dissolved in it).
- Dry natural gas (characterized by a low content of hydrocarbons dissolved in it, the condensate yield is low).
- Wet natural gas (produced in gas condensate fields and is characterized by a high content of gasoline condensate).
The amount of liquid components in natural gases varies from 0.000010 to 0.000700 m³ per 1 m³ of gas. For example, the yield of stable gas condensate at various fields:
- Vuktylskoye (Komi Republic) - 352.7 g / m³;
- Urengoyskoye (Western Siberia) - 264 g / m³;
- Gazlinskoye (Central Asia) - 17 g / m³;
- Shebelinsky (Ukraine) - 12 g / m³.
Natural gas condensate is a multicomponent mixture of various low-density liquid hydrocarbons in which gaseous components are present. It condenses from the raw gas during lowering temperatures when drilling wells (below the dew point of the produced hydrocarbons). It is often referred to simply as "condensate" or "gas gasoline."
The schemes for separating condensate from natural gas or oil are varied and depend on the field and purpose of the products. As a rule, in a technological installation constructed near a gas or gas condensate field, the produced gas is prepared for transportation: water is separated, sulfur compounds are purified to a certain limit, hydrocarbons C1 and C2 are transported to the consumer, a small fraction of them (from the produced) are pumped into reservoirs for pressure maintenance. The separated fraction (after removal of C3 components from it, but with a small content) is the gas condensate that is sent as a feed stream to refineries or to petrochemical synthesis plants. Transportation is carried out by pipeline or bulk transport.
Gas condensate at refineries is used as raw material for the production of gasoline with a low octane rating, to increase which antiknock additives are used. In addition, the product is characterized by a high cloud point and solidification temperature, so it is used to produce summer fuel. As diesel fuel, gas condensate is used less often, since additional dewaxing is required. This direction uses less than a third of the condensates extracted.
The most interesting technological solution is the use of a product such as a wide fraction of light hydrocarbons for petrochemical synthesis. With its receipt begins the processing of gas condensate. Deeper processes continue at the pyrolysis plants, where NGL is used as a raw material for the production of important monomers such as ethylene, propylene, and many other related products. Then ethylene is sent to the polymerization unit, from it polyethylene of various grades is obtained. Polymerization of propylene produces polypropylene. The butylene-butadiene fraction is used to make rubber. Hydrocarbons C6 and higher are raw materials for the production of petrochemical synthesis (benzene is obtained), and only the C5 fraction, which is a raw material for the production of the most valuable products, is used so far inefficiently.