铁离子对原油乳状液破乳脱水的影响

Effect of Iron Ion on the Demulsification of Crude Oil Emulsions

陶俊 段明 方申文

TAO Jun，DUAN Ming，FANG Shenwen

为揭示铁离子对原油乳状液破乳脱水效果的影响规律，考察了铁离子对原油乳状液稳定性的影响以及铁离子在油水两相间的分配系数、原油中的赋存状态。结果表明，随着乳状液中铁离子浓度的增加，破乳脱水量逐渐减少，当含水40%乳状液中的铁离子含量为500 mg/L时，原油乳状液几乎不脱水。在原油乳化过程中，水相中的铁离子向油相中转移。100、300、500 mg/L的Fe2+溶液或Fe3+溶液与原油混合后，测得Fe2+、Fe3+在水中的分配系数分别为0.2327、0.2013、0.2380 和0.2658、0.1837、0.2515。分别用蒸馏水、酸性水和乙腈对原油进行萃取，测得Fe2+、Fe3+平均脱除率分别为85.4%、96.5%、91.3%和84.2%、94.8%、91.5%，表明铁元素在原油中主要以油溶性石油酸盐形式存在。当Fe2+质量浓度由0 增至500 mg/L 时，乳状液电导率由0.008 增至0.025 μm/cm。铁离子增加了原油乳状液的稳定性和电导率，使得乳状液破乳脱水困难，且电脱水过程中电流出现峰值的时间延长。当含水10%乳状液中的铁离子含量达到1000 mg/L时，原油乳状液电脱水过程中会发生电脱水装置短路。图7表4参17

In order to reveal the influence of iron ion on the demulsification and dehydration of crude oil emulsion，the effect of iron ion on the stability of crude oil emulsion，the partition coefficient of iron ion between oil phase and water phase，and the type of iron ion in oil phase were investigated. The results showed that the dehydration ratio of the emulsion decreased during the demulsification with increasing iron ion content in the emulsion. In addition，the emulsion did not dehydrated when the iron ion content was 500 mg/L in an aqueous emulsion of 40%. The transition of iron ion from water phase to oil phase happened during the crude oil emulsification process. After 100，300，500 mg/L Fe2+ or Fe3+ solution were mixed with crude oil respectively，the partition coefficient of Fe2+ and Fe3+ in water phase was 0.2327，0.2013，0.2380 and 0.2658，0.1837，0.2515，respectively. After the crude oil was extracted by distilled water，acidulous water and acetonitrile，the corresponding average remove rate of Fe2+ and Fe3+ was 85.4%，96.5%，91.3% and 84.2%，94.8%，91.5%，respectively，which indicated that the iron ion mainly formed oil-soluble petroleum acid salt in crude oil. When the concentration of Fe2+ increased from 0 to 500 mg/L，the conductivity of emulsion increased from 0.008 to 0.025 μm/cm. The iron ion increased the stability and conductivity of crude oil emulsion，which made the demulsification become difficult and the time of peak current was extended during electric dehydration process. The emulsion containing 10% water led to short circuit of electric dehydrator when the mass concentration of iron ion was 1000 mg/L.