| At present, most of the oilfield has entered into exploiting petroleum later period, tertiary oil production gets more and more application, which polymer flooding recovery technique has been in victory, daqing oilfield application and many other big oilfields and achieve good displacement effect. In recent years, with the development of polymer flooding recovery production, the amount of produced water increases greatly, and the property of the produced water becomes more complicated and more difficult to be treated due to the application of chemical flooding. The waste water treated by current treatment technology cannot meet the standard of the effluent and injecting water. These problems have lagged the development of the oil companies. Therefore, the treatment of produced water is a key problem to be solved in oil production. However, owing to the lack of the knowledge of the property and mechanism of the stability of the produced water, the technology of the treatment of the produced water has not been developed at present. It is necessary to study the nature of the waste water and to find the key factors which dominate the stability of the produced water.Polymer flooding produce water not only contain large remnants of HPAM, and through underground reservoir, will inevitably with formation of have certain surface activity solid particles, and solid particles affect the emulsion stability is one of the important factors. In this thesis, simulation experiments were carried out to study the effects of HPAM and Na-montmorillonite (Na-Mt) particles on the stability of the O/W emulsion and interfacial properties between oil and water, especially on the zeta potential of the oil droplets, as well as on the interfacial properties between oil and water. In order to investigate the mechanism of the stability of produced water from oilfield, the interfacial properties, such as, the interfacial tension, interfacial viscosity and interfacial electrical properties were measured and considered.The result shows that with the increase of Na-Mt particles concentration, when the Na-Mt particles concentration was less than 200 mg/L, the Na-Mt particles can cause the zeta potential of oil droplets decrease rapidly, Interfacial tension decline and Dilational viscoelasticity enhance, and the pictures show that a stable oil-mineral aggregates(OMA) structure has appeared in polymer flooding produced water. They have noticeable effects on emulsification stability of polymer flooding produced water, thus the polymer flooding produced water was stable in this stage. When the Na-Mt particles concentration was more than 250 mg/L, the zeta potential of oil droplets keeps stable, while Interfacial tension and Dilational viscoelasticity shows a slight increase. It can be seen from the pictures that the system formed a large oil-mineral aggregates structure, oil droplets were apt to aggregate, and could enhance the treatment of polymer flooding produced water.The oil-mineral aggregates(OMA) can be formed by the reaction of Na-montmorillonite and oil droplets in emulsion containing Na-montmorillonite, and the structure of the OMA was influenced by the chemical flooding agents in the aqueous solution. There exists a lot of water in OMA because of hydration of the Na-montmorillointe and HPAM. Therefore, the stability of the O/W emulsion is enhanced and the separation of oil and water becomes more difficult. The primary law of the effects of the components existing in the produced water on the stability of the O/W emulsion and clay suspensions was developed in this dissertation. These results are not only important for the development of theory but also practicable for the reference of the later study on the mechanism of the stability and treatment of the produced water. |
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