Hydrocarbon oils, particularly heavy crude oils, contain polar hydrocarbon compounds such as naphthenic acids, nitrogen and sulfur containing hydrocarbon compounds and pose problems in refining. There is a need to upgrade such hydrocarbon oils. Separation of polar hydrocarbon compounds such as naphthenic acids, nitrogen and sulfur containing hydrocarbon compounds from crude oils results in upgrading. The present invention addresses this need.
Hydrocarbon oils, particularly crude oils when produced comprise varying amounts of water and inorganic salts like halogens, sulfates and carbonates of Group I and Group II elements of The Periodic Table of Elements. (The Periodic Table of Elements is the common long form of the periodic table; Advanced Inorganic Chemistry by F. A Cotton and G. Wilkinson Interscience Publishers, 1962) Removal of water from produced crude oils is termed dewatering and salt removal is termed desalting. Often, the process of dewatering also desalts the crude oil since water-soluble salts are removed with the water.
Dewatering the produced crude oil is desired at crude oil production facilities as it impacts the value of crude oil and its economic transportation. The presence of salts, especially chlorides of Group I and Group II elements of The Periodic Table of Elements, corrode oil processing equipment. In order to mitigate the effects of corrosion, it is advantageous to reduce the salt concentration to the range of 1 to 5 ppm or less and water content to about 0.25 to 1 wt % by weight of the crude oil prior to transportation and processing of the oil.
Among the crude oil dewatering and/or desalting methods in use today, electrostatic separation methods are commonly used. Heavy crude oils containing high concentrations of asphaltenes, resins, waxes, and napthenic acids are difficult to dewater and desalt and usually require longer processing times, higher process operation temperatures and higher concentrations of demulsifier chemicals to effect the desired dewatering and desalting. As a result of these processing requirements for heavy crude oils the process throughput is lowered and costs for dewatering and desalting increased. Consequently, there is a need for improved crude oil dewatering and/or desalting methods that improve the efficiency of dewatering and/or desalting especially with heavy crude oils containing asphaltenes and naphthenic acids. The present invention also addresses this need.