氢键抑制方法减少瓜尔胶压裂液对砂岩储层的吸附伤害

为了减轻瓜尔胶压裂液在砂岩多孔介质中产生的吸附伤害、降低其对致密砂岩储层渗透率的伤害,以四川盆地中侏罗统沙溪庙组砂岩为研究对象,根据热重实验确定瓜尔胶在砂岩表面的吸附量,并利用X射线电子能谱测试结合岩心流动实验,分析瓜尔胶压裂液在砂岩多孔介质中的吸附作用机理,再通过核磁共振和CT成像,研究压裂液吸附对砂岩孔喉结构变化和氢键抑制剂对压裂液综合性能的影响。研究结果表明:(1)压裂液会吸附在岩石多孔介质内部,导致岩石孔径变小、储层渗透性变差,吸附量约为3.9 mg/g;(2)砂岩表面的含氧基团与瓜尔胶分子形成的多重氢键作用是砂岩多孔介质与压裂液之间发生吸附的主要作用力,氢键抑制剂可以降低瓜尔胶在砂岩中的吸附量和对储层渗透率的伤害程度;(3)氢键抑制剂的加入对压裂液流变性影响不大,但却可以有效地降低破胶液的表面张力和残渣含量。结论认为,氢键抑制剂可以解除瓜尔胶与砂岩的吸附作用,有效地降低瓜尔胶压裂液对储层的伤害,并且不会影响压裂液的综合性能;该研究成果对于认识氢键抑制剂的性能、改进瓜尔胶压裂液体系、提高致密砂岩储层的增产改造效果等都具有重要的意义。

Hydrogen bond inhibition method: Reducing the adsorption damage of guar fracturing fluid to sandstone reservoirs

In order to reduce the adsorption damage of guar fracturing fluid to porous sandstone media and relieve its damage to the permeability of tight sandstone reservoirs, we took the sandstones of the Shaximiao Fm, Middle Jurassic in the Sichuan Basin, as the research object in this paper. The adsorption capacity of guar gum on the sandstone surface was determined by conducting thermogravimetric experiments. Then, the adsorption mechanisms of guar fracturing fluid in porous sandstone media were analyzed using X-ray photoelectron spectroscopy test combined with the core flow experiment. Finally, the change of sandstone pore throat structure caused by the adsorption of fracturing fluid and the effect of hydrogen bond inhibitor on the comprehensive performance of fracturing fluid were studied by means of nuclear magnetic resonance and CT image. And the following research results were obtained. First, fracturing fluid can be adsorbed inside porous rock media, leading to the reduction of rock pore size and the deterioration of reservoir permeability, and its adsorption capacity is about 3.9 mg/g. Second, the multiple hydrogen bonds composed of oxygen groups and guar molecules on the sandstone surface are the main action for the adsorption between porous sandstone media and fracturing fluid, so hydrogen bond inhibitor can reduce the adsorption capacity of guar gum in sandstones and decrease its damage degree to reservoir permeability. Third, the addition of hydrogen bond inhibitor has little effect on the rheological properties of fracturing fluid, but it can greatly reduce the surface tension and residual content of gel breaking fluid. In conclusion, hydrogen bond inhibitor can eliminate the adsorption between guar gum and sandstones and effectively decrease the damage of guar fracturing fluid to reservoirs without any effect on the comprehensive performance of fracturing fluid. The research results are of great significance to understanding the performance of hydrogen bond inhibitor, improving guar fracturing fluid system, and promoting the stimulation effects of tight sandstone reservoirs.