关键词: 稠油, 乳化降黏剂, 耐高温, 油/水界面活性, 协同作用

Abstract:

With the widely exploitation and development of conventional oil reservoirs, the heavy oil has become the important resources in oil production and attracted great attentions to be the solution of the energy crisis in our country. The heavy oil is usually exploited by thermal and emulsification methods to decrease the viscosity, which require the emulsified viscosity reducer with excellent performance under high temperature conditions. Therefore, aimed at the problems of high viscosity and poor fluidity for heavy oil in Henan Oilfield, several emulsified viscosity reducers were investigated at different types and concentrations to obtain an optimum formula. Then, the emulsification performance of the optimum viscosity reducer under high temperature was further tested to study its temperature resistance ability. Finally, the emulsification mechanisms were explored by investigating the pH values, surficial tensions （SFT） and oil/water interfacial tensions （IFT）. The results show that the optimum formulation of emulsion viscosity reducer is BY-2 with the mass fraction of 0.4%. The emulsified viscosity reduction rate of the heavy oil can reach up to 97.36% under the reservoirs conditions of 50 ℃ and oil/water volume ratio of 7∶3. Moreover, the viscosity reducer exhibits excellent ability of high temperature resistance. It can maintain effective oil/water interfacial activity and emulsification ability after aging 6 h at 300 ℃, which is beneficial to apply in thermal recovery process for heavy oil. The alkaline components in the emulsified viscosity reducer can form the in-situ surfactant with petroleum acids in heavy oil, thereby producing synergistic effects to significantly reduce the SFT, oil/water IFT and improve the emulsification performance. Consequently, this study can provide technical support for the research and development of emulsified viscosity reducer with properties of efficient viscosity reduction and high temperature resistance for heavy oilfields.

Key words: heavy oil, emulsified viscosity reducer, high temperature resistance, oil/water interfacial activity, synergistic effect