The Stability Analysis And Synthetical Treatments Study Of Aging Oil

Aging oil is a kind of stable crude oil emulsion with severe emulsification and high stability. The high water content and complicate components of it easily leads to the disqualification of clean oil and the failure of electric dehydration device. The large content of heavy components(resin, asphaltenes, et al.) and surfactants(solid impurities, et al.) in aging oil causes its formation and stability. At present, aging oil is mainly treated by mixing with clean oil or chemical settlement. However, none of them is effective. In this paper, based on the aging oil in Fuyu and Xinmu treating stations of Jilin oilfield and through the combining of micro droplet sizes distribution and macro dehydration effect, the stability reason and treating methods of aging oil were studied.On the stability analysis of aging oil, researches showed that: Temperature had little influence on the stability of aging oil. The distributions of water droplet sizes were similar to log-normal distribution with little difference to each other. Only heating could not make water droplets in aging oil coalesce. The optimal heating temperature was set at 60 °C. Droplet sizes mainly concentrated in 5~12μm. Too small the droplet size made the water droplets difficult to coalesce, which is the root cause of the strong stability of aging oil. Results of X-ray diffraction showed that aging oil contains large amounts of Fe S. The dehydration effect improved obviously after the removal of Fe S, which indicates that the existence of Fe S is another important reason for the stability of aging oil. Strong acids or strong oxidizing agents could be used for the removal of Fe S.On the treatments studies of aging oil, electrostatic coalescence, centrifugal separation, ultrasonic treatment and diluting with diesel were mainly studied. Experiments showed that: Electrostatic coalescence could not make aging oil demulsificate and dehydrate. The change of waveform, voltage, frequency, electric acting time or other electrical parameters had little effect on the droplet sizes distribution. Centrifugal method could be used for the treatment of aging oil. Aging oil divided into four layers after centrifugation, and the difficulty of dehydration lay in the oil-water transition layer. When KMn O4 solution was used for the removal agent of Fe S, the optimal centrifugal parameters were 1500 g with 6min or 2000 g with 4min. The ultrasonic effect would cause large droplets to disperse in aging oil, which made it unable to be used in the treatment of aging oil. Diluting with diesel made the viscosity of aging oil decrease greatly, however, water droplets still could not coalesce under gravity. The optimal diluting ratio of Fuyu aging oil was 15%, and Xinmu aging oil was 20%. Diluting combining with electrostatic coalescence or ultrasonic treatment was still unable to make aging oil demulsificate and dehydrate, but it could improve the treatment effect of centrifugal separation.