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Composition and structural characteristics of floaters were detected and forming reasons were analysed through modern reservoir engineering theory, equipment analysis and physical simulation.Experiments on flowing characteristics, fluid diversion effect and driving effect were carried out. The results show that floaters are formed by huge amounts of tiny bubble absorbing crude oil and suspended solids in floating progress which make their density lower than water. Disposed floaters have better adaptability and can block off high-permeability. Furthermore, profile control effect turns better as particle concentration and permeability ratio increases. However,floater particles have selectivity to permeability ratio. When permeability ratio is not less than 8, profile control agent may damage low-permeability layers and cause succeeding water passing through high-permeability layers. Therefore, only when floaters adapt well to permeability ratio can we get better profile control effect.

Xinbei Oilfield in Jilin is a tectonic lithology reservoir with high porosity, high permeability, thin oil layers and severe heterogeneity, which has entered a period of high water-cut development. Aiming at actual demand of field development, making use of indoor apparatus monitoring and theoretical analysis method, the author evaluated the viscosity, interfacial tension, absorption characteristics, rheological property, viscoelasticity and displacement efficiency of 5 different binary composite systems composed of surfactants and polymer to optimize the binary flooding system. The results show that Daqing Lianhua/Polymer system can achieve ultra-low interfacial tension with crude oil with small absorption, well stability and little effect on viscoelasticity of polymer solution. The system has higher displacement efficiency and stronger mobility control ability, which is recommend as flooding system for oilfield.

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