Stability And Processing Method Of Sewage In Nanyang Oil Field

With the development and continuous exploration of oil fields, tertiary recovery technology has found a increasingly wide utilization, especially on surfactant enhanced oil recovery. For improving flooding effect, in terms of adding polymer, surfactant or polymer and surfactant compound into water may lead to many problems, such as chemical constituents of the produced liquid became more complex and multiplex; The produced liquid stability was significantly improved and the difficulties of Water-oil separation was increased. The efficiency of oil recovery would be decreased by injection of untreated wastewater, since the Oil capillary channel blocking, reservoirpermeability dropping and even water absorption ability dropping that lead by suspended particulate and oil globules in the untreated wastewater.In this study, produced water of Nan yang oilfield was analyzed. And the effects of oil displacement agents on oil water separation of simulated water, Zeta potential, oil water interfacial rheology were investigated, and the stability mechanism of produced water was conducted, the processing method was studied.The results show that the existence of surface active agent increases the difficulty of water-oil separation, and the higher the concentration was, the worse effect of settlement was. It was found that a different ion of produced water water-oil has different separation effects. The satisfied result of water extraction was obtained by using Al3+、Na2CO3、Mg2+.The result of water extraction could be promoted slightly by the existence of NaCl. The existence of NaHCO3has big implications for result of water extraction. The difficulty of water extraction was increased by the existence of Ca2+and Fe3+. The result of SO42-、S2-、Fe2+effect of water extraction is little. When oil content amount less than2000mg/L, the viscosity of sewage nearly has no efficacy.The interfacial tension of the oil-water interface and the Zeta potential absolute value of particle surface were decreased and increased respectively with increasing concentration of surfactant, but the oil-water interface shear viscosity was changed mildly; in the surfactant-polymer binary compound system (SP), polymer, surfactant and the suspended substance in water formed a Thermodynamics unstable system with a similar "crystal" structure.The result shows that the optimal conditions for treatment of simulated wastewater is temperature50℃,coagulant three dosage1000mg/L, coagulant dosage10mg/L. Under these conditions, the light transmission rate of the under clear liquid is99.8%.