Effects Of Hectorite Particles On Emulsification Stability Of Polymer Flooding Produced Water

Most oil fields in China have reached the tertiary recovery stage. Polymer flooding has been found to greatly enhance oil recovery and hence has been widely used in many Oilfields. With the development of polymer flooding, the amount of produced water increases greatly and the property of the produced water becomes more complicated and more difficult to be treated than that from water flooding. If the polymer flooding produced water is not handled properly, the injection and efflux will risk to the oil wells and environment. Thus the treatment of produced water is a very important and urgent task.Since strong emulsification stability is the key feature of the produced water, effective destabilization should be achieved to treat this kind of waters. Similar to other emulsions, the stabilization mechanisms of produced water are as follows: interfacial tension stability, interfacial film stability, and double-layer stability, space stability and solid particles stability. The produced water takes out of clay particles as crude oil flows through the underground reservoir, and solid particles is also a factor affecting emulsion stability. Thus, it is important to study the stabilization mechanism of clay and the synergy of Clay-polymer.In this paper, simulation experiments were carried out to study the effects of HPAM and hectorite particles on the stability of the emulsion. The interfacial properties, such as the zeta potentials, interfacial tension and dilational viscoelasticity, between oil and water were also studied. Hectorite in place of natural clay was used to investigate the stabilization mechanism of clay and the synergy of Clay-polymer.The results indicated that, with the increase of hectorite particles concentration up to100mg/L, the Zeta potential of oil droplets become more negative, the interfacial tension decreased greatly, the dilational viscoelasticity enhanced and a stable oil-mineral aggregate structure appeared. On the other hand, with further increase of hectorite particle concentrations, Zeta potential of oil droplets kept stable, interfacial tension slightly increased, and dilational viscoelasticity decreased. When the concentrations of hectorite particles were less than150mg/L, the polymer flooding produced water was stabilized. In the system a large oil-mineral aggregate structure was formed with the increase of hectorite particles up to150mg/L, which was apt to aggregate, could favor the polymer flooding produced water treatment.