淀粉接枝/硅酸钠复合凝胶体系的制备及封堵性能评价

对淀粉与丙烯酰胺的接枝共聚反应进行了研究,确定了反应条件后,再加入硅酸钠-USC(成胶控制剂)溶液,反应10 h后最终形成了一种有机-无机复合凝胶。流变性实验结果表明,体系中加入硅酸钠后,其储能模量和耗损模量均大于原接枝体系。相同条件下,复合凝胶材料的柔量低于淀粉接枝体系,即其形变能力较差;随着温度的增加,复合凝胶的柔量降低,体系的形变能力随温度变化较敏感。封堵实验结果表明,不加硅酸钠的接枝共聚物对填砂管的封堵率达到97%,而复合凝胶材料的封堵率达到99.9%。这是由于硅酸钠凝胶的存在,增加了凝胶自身强度,生成的凝胶与岩石颗粒有一定的粘接力,从而明显提高了体系的封堵强度。

Preparation of the Starch-graft Sodium Silicate Composite Gel and Evaluation of Its Plugging Properties

The graft copolymerization of starch/acrylamide was studied and its reaction conditions were modified.With the addition of sodium silicate/USC solution,an organic-inorganic composite gel was developed after 10 h reaction.It was indicated in the rheological experiments that the gel with the addition of sodium silicate had larger storage modulus than before.Under the same conditions,the composite gel had lower compliance than starch graft gel,which confirmed its poor deformation capability.With the increase of temperature,the compliance of the composite gel showed accelerating reduction,which indicated its sensitivity of deformation capability to temperatures.The plugging experiments indicated that both the gel intensity and its plugging strength were improved because of the existence of sodium silicate gel as well as its adhesion with rock grain.The plugging rate of graft copolymers without sodium silicate could reach 97% in sand pack,while it was 99.9% for the composite gel.