基于动态共价键的热响应暂堵用水凝胶的制备及性能

Preparation and properties of thermoresponsive hydrogels based on dynamic covalent bonds for temporary plugging

针对化学凝胶封堵油气管道实现热工作业后难以破胶的问题,基于动态共价键和氢键作用,以胍胶、琼脂和十水四硼酸钠制备了一种具有热响应破胶的水凝胶。通过红外光谱和扫描电镜表征了凝胶的形成机制以及微观形貌;利用流变仪研究了水凝胶的机械性能和热响应行为。结果表明,随着胍胶含量的增加,水凝胶的机械强度逐渐增大,凝胶-溶胶转变温度也越高。向凝胶体系中加入适量的琼脂,可以降低凝胶-溶胶的转变温度,以此提高水凝胶的破胶效率。利用自制可视化管道研究了该水凝胶的封堵与解堵性能,结果表明,该水凝胶具有优异的封堵性能,封堵段长度为100cm时,能够承受0.156MPa的突破压力。使用70~90℃的热水冲洗水凝胶,10cm长的封堵段能在100min内完全解堵。该水凝胶作为封堵材料能够保证管线热工作业安全、简化工艺流程,同时避免管道二次损坏等优势,有望代替传统管道封堵用化学暂堵材料。

Aiming at the problem that chemical gel plugging oil and gas pipeline was difficult to break after thermal operation,a hydrogel with thermal responsive gel-breaking was prepared based on the dynamic covalent bonds and hydrogen bonds between guargum,agar and borax.The formation mechanism and morphology of the hydrogel were characterized by fourier transform infrared spectrometer(FTIR)and scanning electron microscopy(SEM).In addition,the mechanical properties and thermal response behavior of the hydrogel were studied by a rheometer.The results showed that the mechanical strength and the gel-sol transition temperature of hydrogel were enhanced with the increase of guanidine concentration.Furthermore,adding appropriate amount of agar into the gel system could decrease the gel-sol transition temperature of the hydrogel,thereby improving the gel breaking efficiency of the hydrogel.And the plugging and unplugging performance of the hydrogel was also studied by using self-made visual pipe.The results showed that the hydrogel had excellent plugging performance which could withstand the breakthrough pressure of 0.156 MPa with a 100 cm plugging section length.The plugging section with a length of 10 cm could be completely unplugged within 100 minutes when the hydrogel was washed acutely with hot water at 70~90℃.Hence,the hydrogel could ensure the pipeline thermal operation safety,simplify the process flow,and avoid the pipeline secondary damage,and it was expected to replace the traditional chemical plugging materials used for pipeline plugging.