The chemical composition

The overall composition

Petroleum is a mixture of about 1,000 individual substances of which the majority - liquids (> 500 substances or usually 80-90% by weight) and heteroatomic organic compounds (4-5%), mainly sulfur (about 250 agents), nitrogen ( > 30 substances) and oxygen (85 substances), and organometallic compounds (mainly vanadium and nickel), and the remaining components - dissolved hydrocarbon gases (C1-C4, from tenths to 4%), water (from trace to 10% ), mineral salts (mainly chlorides, 0,1-4000 mg / l or more), solutions of salts of organic acids, etc., mechanical impurities.
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Hydrocarbon composition

Basically in paraffin oil are (usually 30-35, sometimes 40-50% by volume) and naphthenic (25-75%). To a lesser extent - aromatic compounds (10-20, at least 35%) and mixed or hybrid, structure (eg, paraffin-naphthenic, naphthene-aromatic).
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The elemental composition of oil and heteroatomic components

Along with the hydrocarbons in the oil are substances containing impurity atoms. Sulfa - H2S, mercaptans, mono-and disulfides, thiophenes and Thiophane and polycyclic etc. (70-90% is concentrated in the residual products - fuel oil and tar), nitrogen - mainly homologues of pyridine, quinoline, indole, carbazole, pyrrole, and porphyrins (mostly concentrated in the heavy fractions and residues), oxygen - naphthenic acids, phenols, resin-asphaltene and other substances (usually concentrated in high fractions). The elemental composition (%): 82-87 C; 11-14,5 N; 0,01-6 S (rarely to 8); 0,001-1,8 N; 0,005-0,35 O (rarely to 1.2) etc. A total of 50 oil found items. So, along with the above, the oil contains V (10-5 - 10-2%), Ni (10-4-10-3%), Cl (from traces to 2.10 -2%), etc. The content of these compounds and impurities in the raw materials of different deposits varies widely, so to speak of the average chemical composition of the oil can only conditionally.