Selley, RC; Sonnenberg, SA; Selley, RC; Sonnenberg, SA
Natural gas and crude oil are two of the chemically and physically diverse group of compounds called hydrocarbons. Hydrocarbon molecules are classified based on their molecular structure as paraffins, napthenes, and aromatics. Hetercompounds also contain carbon and hydrogen but also other elements such as oxygen, nitrogen, and sulfur. Hydrocarbon gases consist mainly of hydrocarbons of the paraffin series (i.e., methane, ethane, propane, butane, and occasionally pentane). Inert gases are a minor accessory in natural gas. Common inert gases are helium, hydrogen, carbon dioxide, and hydrogen sulfide. Gas hydrates are compounds of frozen water that contain gas molecules. Hydrates are formed in shallow artic sediments and in deep ocean deposits. Crude oils are mixtures of hydrocarbons that exist in liquid state in natural underground reservoirs and remain liquid at atmospheric pressure. They consist mainly of carbon and hydrogen with traces of vanadium, nickel, sulfur, oxygen, and nitrogen and are classified based on their percentage of paraffin, naphthene, and aromatic compounds. Typical refined petroleum products of crude oils include gasoline, kerosene, diesel fuel, lubricating oil, and residuum.