表面活性剂的润湿性及增注机理研究

The Rock Wettability and Stimulation Mechanism of Surfactants

研究了改变低渗透砂岩亲水性油气层润湿性对增注性能的影响。通过测定表面张力和润湿角筛选出了常规表面活性剂ABS、OPT以及两性Gemini表面活性剂GC26。通过岩心驱替试验考察了表面活性剂的增注性能和对岩心的油水相对渗透率的影响。结果表明,0.5%ABS、0.1%GC26、0.5%OPT的表面张力分别为25.07、28.33、29.57mN/m。活性剂处理岩心后,岩心表面润湿性向弱亲油方向移动,等渗点时含水饱和度下降,尤其是Gemini表面活性剂GC26,含水饱和度降到48%,显示出孔喉表面转变为亲油,岩心水相渗透率提高幅度达到86.57%,具有较好的增注效果。结合GC26的结构特点及表面性质,分析了表面活性剂增注效果的差异,认为提高吸附膜的致密性及疏水性程度是增注的关键。

The effect of wettability of water-wet reservoirs with low permeability on stimulation property was studied.Surfactants ABS,GC26 and OPT as well as Gemini Surfactant were screened out by detecting its surface tension and wettability.The effects of surfactants on stimulation property and on oil-water permeability of cores were studied by detecting surface tension.The injection mechanism of surfactants were discussed by relative permeability.The results show that the surface tensions of 0.5%ABS,0.1%GC26 and 0.5% OPT are 23.07,28.33 and 29.57 mN/m respectively,and wettability of the core surfaces was altered from water wet reservoirs to weak oil wet reservoirs,especially,water saturation of Gemini surfactant GC26 was reduced to 48% as water saturation was reduced at isotopic point.When water saturation of cores was risen to 86.57%,the wettability on pore throat surface was turned to oil wet and good oil incremental effect was obtained.In combination with the structural features and its surface property of GC26,the differences of stimulation of the surfactant are analyzed,it is considered that the key factor for enhancing the stimulation effect is to raise the compactness of adsorption and hydrophobic level.