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Abstract
The desalting and dewatering of six crude oils with deferent properties have been studied. The contents of asphaltene and resin of #1, #2, and #4 crude oil are high; the demulsifiers with higher lipophilic values than others in the same series such as DA2, DB2, and DC2 can be easily absorbed on the interface of a water–oil emulsion and reveal better dewatering and desalting efficiency. The carbon atom number of alkyl on phenol core in nonyl-alkylphenol formaldehyde resin, which is the initiator of the DC series, is more than that of the DB series. DC was easier to diffuse into the interface of water in oil, and the dewatering efficiency increased. Because more multipoint adsorbed, their dewatering rate was slower, and the salts can dissolve in washing water and be removed with water. The density and viscosity of #3 crude oil are lower, and wax content is high. The hydrophilic group and lipophilic group in the molecular of DA4, DB4, and DC4 demulsifier can well be absorbed on the interface of water–oil emulsion of #3 crude oil, which have better efficiencies of desalting and dewatering than other demulsifiers of their same series. The density, viscosity, and wax content of #5 and #6 crude oils are lower; however, sulfur content is high. The self-made demulsifiers have excellent dewatering efficiency for #5 and #6 crude oil, but the desalting efficiency is unsatisfied, because the content of salts sulfate and sulfide in #5 and #6 crude oil is high as shown in the analysis of anion content before and after desalting. It can be improved by adding acid assistant TJ1, TJ2, and TJ3, thus indiffluent salts sulfate and sulfide transform into diffluent salts that can be removed, so the desalting efficiency obviously increases.
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