Petroleum By-Product Gases

hydrocarbon gases associated with petroleum and liberated from it during separation. The amount of gas (in cu m) received per ton of extracted petroleum (the so-called gas factor, or gas-oil ratio) depends on the formation and stratification of the petroleum deposits and can fluctuate from 1-2 to several thousand cu m per ton of petroleum. The total output of petroleum byproduct gases in the USSR amounted to 18.8 billion cu m in 1967. Unlike natural gas fuels, which consist primarily of methane, petroleum by-product gases contain considerable quantities of ethane, propane, butane, and other saturated hydrocarbons. In addition, water vapors and sometimes also nitrogen, carbon dioxide, hydrogen sulfide, and rare gases (helium, argon) are present in petroleum by-product gases.

Prior to delivery in trunk gas pipelines, petroleum byproduct gases are processed in gas refineries that produce casing-head (natural) gasoline, so-called stripped gas, and hydrocarbon fractions, which are technically pure hydrocarbons (such as ethane, propane, butane, and isobutane) or their mixtures.

Casing-head (natural) gasoline is used as a component of motor-vehicle gasolines. Liquefied gases (propane-butane fraction) are widely used as a motor fuel for motor transport or as a fuel for municipal utilities. Hydrocarbon fractions constitute a valuable raw material for the chemical and petrochemical industries. They are widely used for the production of acetylene. Ethylene, an important product for organic synthesis, is produced by the pyrolysis of ethane. Acetaldehyde, formaldehyde, acetic acid, acetone, and other products are formed during the oxidation of propane-butane fractions. Isobutane is used for the production of high-octane components of motor fuels and also of isobutylene, a raw material for the manufacture of synthetic rubber. Isoprene, also an important product for the manufacture of synthetic rubbers, is produced by the dehydrogenation of isopentane.