Gas condensate, properties, production, application.
Gas condensate is a mineral, liquid mixture of heavy hydrocarbons, extracted from natural gas during production in gas and condensate fields or from associated gas during oil production from the oil fields.
Gas condensate is a useful fossil, liquid mixture of heavy hydrocarbons, extracted from natural gas during production in gas and condensate fields or from associated gas during oil production from the oil fields.
Externally, as a rule, gas condensate is a clear, colorless liquid. Because of this, he was called “white oil”. Sometimes gas condensate becomes weak in color from straw-yellow to yellow-brown color, due to the presence of impurities in the oil, heavy hydrocarbons.
Gas condensate is always present in the deposits of natural gas. As you know, natural gas is a mixture of hydrocarbon and non-hydrocarbon components. The first is represented by methane CH4 and its homologues: С2Н6 ethane, propane C3H8, butane C4H10, pentane С5Н12 hexane С6Н14, С7Н16 heptane, octane С8Н18, nananom С9Н20, Dean С10Н22, etc. until proven С22Н46. Gas condensate is a mixture of heavy hydrocarbons ranging from pentane С5Н12 and above.
Pentane has three isomers: normal pentane, isopentane and neopentane. Two isomers of pentane (normal pentane and isopentane) in normal conditions volatile mobile liquid. Neopentane the same gas. Subsequent hydrocarbons (from hexane С6Н14 and higher) under normal conditions are liquids.
In gas and gas condensate deposits of heavy hydrocarbons exist in gaseous state. This is due to high pressure (from 10 to 60 MPa) and high temperature gas formations. After drilling wells in the reservoir there is a drop in temperature and pressure. If the pressure reduction and the temperature is below the dew point of the heavy hydrocarbons (from С5Н12 and above) congenerous.
Concentration in the produced natural gas gas condensate can reach 5 g/ m3 to 1000 g/ m3. It all depends on the quality of natural gas, the ratio of its dryness. Dry natural gas contains a very small amount of impurities gas condensate, crude (fat) – more – more than 15 %.
Also the concentration of gas condensate in natural gas is influenced by temperature and pressure before the start of condensation. The bigger they are, the more hydrocarbons can be dissolved in the produced natural gas.
Formation can be so-called “oil rims”, i.e. part of the deposits containing oil, gas and condensate. Oil rims not only increase the concentration of condensate in the produced gas, but also added to the composition of the gas condensate high molecular weight liquid components of the oil.
Unlike gas condensate from oil – the absence in it of resinous substances and asphaltenes. We can say that gas condensate is essentially light crude oil.
Like natural gas gas condensate is a mixture of hydrocarbons. It includes some of the gasoline-kerosene fraction and, rarely, more liquid high-molecular oil components. Sometimes there are no aromatic or naphthenic hydrocarbons.
Distinguish between stable and unstable gas condensate.
Unstable gas condensate also includes the light fraction of hydrocarbons, ranging from methane CH4 and ending with butane C4H10. These gases dissolved in the gas condensate.
If unstable gas condensate is subjected to the purification, separation and remove these light hydrocarbons (methane CH4, ethane С2Н6, propane C3H8 and butane C4H10), we get a stable gas condensate.
Thus, stable gas condensate contains С5Н12 pentane, hexane С6Н14, С7Н16 heptane, octane С8Н18, nonan С9Н20, Dean С10Н22, etc. until proven С22Н46, as well as gasoline-kerosene fraction, a gas oil, more liquid high-molecular components of oil, aromatic or naphthenic hydrocarbons.
As a rule, gasoline components account for more than half of gas condensate. If the reservoir is at great depth, it is dominated by kerosene and gasoil components.
Stable gas condensate is divided into groups 1 and 2, the content of chloride salts, sulfur compounds KGF in accordance with the table below.
The GOST R 54389-2011 “the Condensate gas stable. Technical conditions”, the following requirements for stable gas condensate:
|Name of the parameter:||The value for the group:|
|Saturated vapor pressure, kPa (mm Hg.St.), no more*||66,7 (500)|
|Mass fraction of water, %, not more||0,5|
|Mass fraction of mechanical impurities, %, not more||0,05|
|The mass concentration of chloride salts, mg/dm3, not more||100||300|
|Mass fraction of sulfur, %***||Off-standard. Determination at the request of the consumer|
|Hydrogen sulphide, mn-1 (ppm), not more than***||20||100|
|Mass fraction of methyl – and ethylmercaptan in sum, million-1 (ppm), not more than*** (****)||40||100|
at 20 °C, kg/m3;
Off-standard. Definition of necessary
|at 15 °C, kg/m3||Off-standard. Determination at the request of the consumer|
|The yield of fractions, % temperature °C:****
|Off-standard. Definition of necessary|
|Mass fraction of paraffin, %||Off-standard. Determination at the request of the consumer|
|Mass fraction of organochlorine compounds, mln-1 (ppm)||Off-standard. Determination at the request of the consumer|
* In coordination with consumers allowed the production of stable gas condensate with a vapor pressure of not more than 93,3 (700) kPa (mm Hg.St.).
** If at least one of the indicators of stable gas condensate belong to the group 2, while other group 1, the stable gas condensate recognized as corresponding to group 2.
*** These indicators determine at the request of the consumer only for condensates with a content of sulfur compounds (calculated as sulfur) more than 0.01% by weight.
****For companies processing sulfide raw materials and commissioned before 1990 allowed for coordination with customers and transport companies exceeding values in terms of the mass fraction of methyl – and ethylmercaptan for stable gas condensate of group 2 to 300 million-1 (ppm) in terms of the release fractions for stable gas condensate of group 2 to 3000 million-1 (ppm).
|Density at 20 ° C, kg/m3 (depends on the hydrocarbon composition)||from 700 to 840|
Gas condensate obtained from natural gas or from associated gas.
In turn, the deposits of natural gas deep within the earth at depths of one to several kilometers. Therefore, in order to get it you need to drill a well. The deepest borehole has a depth of more than 6 kilometers.
After the extraction of natural gas from gas fields it clean, getting the product to purification a gas condensate.
In order for the pressure in the bore has fallen to the atmospheric and remain as long as possible in order to extraction of gas condensate, light hydrocarbons (methane and ethane) is pumped back to until will not be extracted from the heavier fractions. Otherwise, the gas condensate will condense onto and remain in the well.
Of associated oil gas and gas condensate produced by its purification and separation.
From the gas condensate we obtain different types of fuel: high-grade gasoline (AI-80, AI-92, AI-95), jet, diesel and fuel oil. However, such a fuel can be used only in the summer. To use it in the winter it is removed from the glider and add a special additives. Diesel fuels derived from gas condensate, unfortunately, has a low detonation resistance so it further added additives-antidetonators.
Gas condensate is a valuable raw material for use in the petrochemical industry. It is obtained from aromatic hydrocarbons, olefins and other monomers used for the production of plastics, synthetic rubbers, fibres and resins.
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