Study on Wastewater Demulsification Technology of Crude Oil in Xinjiang Oilfield

The Second Oil Production Plant of Xinjiang Oilfield produces a large amount of highly emulsified crude oil, which has a serious impact on the subsequent oil-water separation. At present, the concentration of demulsifier has increased to 2000 mg/L, but the demulsification effect is still poor. In th...

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Bibliographic Details
Published in:Molecules (Basel, Switzerland) Switzerland), 2023-03, Vol.28 (6), p.2873
Main Authors: Ma, Jingui, Ma, Liqiang, Gao, Yongdi, Qin, Yue, Jiao, Zhihao, Guo, Ruibo, Hou, Junwei
Format: Article
Language:English
Subjects:
chemical flooding
Crude oil
demulsification
Desalination
Emulsions
fracturing backflow fluid
Oil
Oil and gas fields
Oil field equipment
Oil fields
Petroleum production
Phase transitions
Physical properties
process optimization
Surfactants
Viscosity
Wastewater
water flooding
Zeta potential
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Summary:The Second Oil Production Plant of Xinjiang Oilfield produces a large amount of highly emulsified crude oil, which has a serious impact on the subsequent oil-water separation. At present, the concentration of demulsifier has increased to 2000 mg/L, but the demulsification effect is still poor. In this paper, the source and physical properties of highly emulsified crude oil are investigated firstly. The results show that highly emulsified crude oil is composed of three kinds of liquid: (1) conventional water flooding (WF); (2) chemical flooding (CF); (3) fracturing backflow fluid (FB). Among them, high zeta potential, low density difference, high viscosity, and small emulsion particles are responsible for the difficulty in the demulsification of the WF emulsion, while the high pH value is the reason why the CF emulsion is difficult to demulsify. Therefore, systematic experiments were implemented to investigate the optimal demulsification approach towards the three liquids above. As for the WF emulsion, it was necessary to raise the temperature to 70 °C and the concentration of the demulsifier to 200 mg/L. Moreover, it was only necessary to add 200 mg/L of demulsifier to break the CF emulsion after adjusting the pH value to 7, while no extra treatments were needed to break the FB emulsion. We hope this study can provide a new insight for the treatment of emulsions in the later stage of oilfield development.
ISSN:1420-3049
1420-3049
DOI:10.3390/molecules28062873