河南油田耐高温稠油乳化降黏剂优选及乳化机理研究

Optimization and emulsification mechanism of emulsified viscosity reducer with high temperature resistance for heavy oil in Henan Oilfield

针对河南油田稠油黏度高、流动性差的问题,对一系列不同类型、不同质量分数的乳化降黏剂配方进行优选,进而研究了高温条件下乳化降黏剂的性能,并探究了最佳降黏剂配方的乳化机理。结果表明,优选出的最佳乳化降黏剂配方为0.4%(w/%)的BY-2,在油水比为7∶3,油藏温度50℃条件下,可产生优异的乳化降黏效果,稠油降黏率高达97.36%。此外,高温对乳化降黏剂的影响较小,在300℃下老化6 h仍能保持优异的油/水界面活性和乳化效果。乳化降黏剂中的碱性组分可与稠油中的石油酸原位生成表面活性物质,进而产生协同增效作用,显著降低油/水界面张力,提升乳化降黏效果。本研究为稠油油田耐高温乳化降黏剂的研制提供了技术支撑。

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.