一种水基钻井液超支化高分子润滑添加剂

Hyperbranched polymer lubricant additive for water-based drilling fluid

传统润滑处理剂设计主要基于油脂的液体润滑理论,忽略了钻井液固相在钻具与井壁极压受限空间内的边界承载和润滑作用。为此,根据Stribeck曲线分析了符合钻进过程的边界润滑行为,并结合人体工学润滑理论,提出了超支化高分子井壁润滑模型及构效关系,采用发散法合成了以乙二胺为内核的超支化高分子聚(丙烯酸甲酯—乙二胺,PMA-EDA),表征了合成产物结构,进行了超支化高分子PMA-EDA与膨润土粒子的成膜检测,并以PMA-EDA为润滑添加剂构建了水基钻井液体系,评价了该体系的应用性能。研究结果表明:(1)目标合成产物PMA-EDA具有超支化构型,其热解温度达到225℃;(2)超支化高分子PMA-EDA可以通过多点吸附,改善与膨润土片层的桥接方式,促进生成具有一定强度的致密、韧性边界润滑膜;(3)对于构建水基钻井液体系,润滑添加剂浓度为4%,可以满足钻井液强润滑性以及热稳定性要求。结论认为,高润滑性能水基钻井液显示出了区别于传统水基钻井液的降摩减磨优越性,其性能评价也进一步证实了超支化分子强化边界润滑成膜模型理论的科学性和实用性。

The design of conventional lubrication treatment agents is mainly based on the grease lubrication theory,but neglects the boundary load and lubrication action of the solid phase of drilling fluid under extreme pressure in the confined space between a drilling tool and the borehole wall.In this paper,the boundary lubricating behavior in line with the drilling process is analyzed on the basis of Stribeck curve,and then combined with the ergonomic lubrication theory,a borehole wall lubrication model and structure-activity relationship of hyperbranched polymer are established.A kind of hyperbranched polymer with ethylenediamine as the internal core,i.e.,polymethyl methacrylate-ethylenediamine(PMA-EDA)is synthesized by using the divergent approach,and its polymeric structure is characterized.Filming behavior of hyperbranched polymer PMA-EDA and bentonite particles is tested.In addition,a water-based drilling fluid system with PMA-EDA as the lubricant additive is constructed,and its application performance is evaluated.And the following research results are obtained.First,the target synthetic product PMA-EDA has hyperbranched configuration,and its pyrolysis temperature is up to 225℃.Second,the hyperbranched polymer PMA-EDA can improve the bridge connection mode with bentonite layers through multi-point adsorption,so as to promote the formation of compact and tenacious boundary lubrication film with certain strength.Third,the suitable concentration of lubricant additive to construct a water-based drilling fluid system is 4%,which can meet the requirements of strong lubricity and thermal stability of drilling fluid.In conclusion,the water-based drilling fluid with polymer lubricity is superior to the conventional water-based drilling fluid in friction and wear reduction,and performance evaluation on the drilling fluid further confirms that the hyperbranched polymer enhanced boundary lubrication filming model are scientific and practical.