聚合物及固体颗粒对原油乳状液稳定性影响机制研究

Study on the influence mechanisms of polymers and solid particles on the stability of crude oil emulsion

为了探明油田作业返排残液影响原油采出液脱水的原因,以返排残液中最常见的非离子型聚丙烯酰胺(NPAM)及瓜胶为聚合物代表,以石英砂为颗粒物代表,研究了单一聚合物、单一颗粒物及聚合物与颗粒物共存影响原油乳状液稳定性的机理。结果表明,单一聚合物对乳状液稳定性影响中,聚合物质量浓度增加至1 000 mg/L,乳状液脱水率降低至0%,粒径分布峰值均小于10μm,黏度成倍增长,含瓜胶乳状液黏度增加了2.80倍,含NPAM黏度增加了1.82倍,平衡界面张力下降,油水界面黏弹性增加且弹性模量是黏性模量的4~5倍,此时界面膜以弹性膜为主,界面膜强度增加,乳状液稳定性增加。单一颗粒物对乳状液影响为含固量增加至1%,乳状液脱水率降低了9.90%,黏度增加了46.36%,油水界面张力降低了9.10%左右。聚合物和固体颗粒叠加影响作用于乳状液,含固量1%且聚合物质量浓度增加时,脱水率从54.50%降低至0%,黏度增加了2.58倍,粒径分布峰值降低了74.97%;这些现象说明乳状液中聚合物和固体颗粒增多,脱水难度增加,乳状液稳定性增加。

To clarify the reasons why the backflow residue of oilfield operation affects the dehydration of produced crude oil,the mechanisms for single polymers,single solid particles and the coexistence of a polymer and particles affecting the stability of crude oil emulsion were studied,in which NPAM and guar gum,which are the most common backflow residues,were taken as the representatives of polymers,and quartz sand as the representative of solid particles.The results showed that single polymers could influence the stability of the emulsion.When the mass concentration of the polymer was increased to 1 000 mg/L,the dehydration rate of the emulsion was decreased to 0%,and the peak of particle size distribution was less than 10 μm.The viscosity was significantly increased,i.e.,the viscosity of the emulsion containing guar gum was increased to 3.80 times,and the viscosity of the emulsion containing NPAM was increased to 2.82times.The equilibrium interfacial tension was decreased,the viscoelasticity of the oil-water interface was increased,and the elastic modulus was 4-5 times that of the viscous modulus.In this case,the boundary film was mainly elastic,the strength of the boundary film was increased,and thus the stability of the emulsion was increased.The influence of single solid particles on the emulsion was that,when the solid content was increased to 1%,the dehydration rate of the emulsion was decreased by 9.90%,the viscosity was increased by 46.36%,and the interfacial tension between oil and water was decreased by approximately 9.10%.The coexistence of a polymer and solid particles had superposition effect on the stability of the emulsion.The increase of the polymer and solid particles in emulsion would increase the difficulty of dehydration and the stability of the emulsion.When the solid particle content was fixed at 1% and the polymer concentration was increased,the dehydration rate was decreased from 54.50% to 0%,the viscosity was increased to 3.58times,and the peak of particle size distribution was significantly decreased.