钻井液用非离子型微乳液WR-Ⅰ的研制及其封堵和润滑作用

摘要

作为油田处理剂,微乳液主要应用于三次采油,在钻井液中的应用未见报道.水平井和定向井钻进过程中经常遇到井壁失稳和摩阻过大的问题,常用的钻井液处理剂功能单一,难以同时兼顾封堵和润滑功能.针对上述问题,以Span-80和Tween-80复合表面活性剂为基础,以正丁醇为助表面活性剂,研制了非离子型微乳液WR-Ⅰ,考察其对钻井液性能的影响,并重点研究其封堵和润滑作用.实验结果表明,非离子型微乳液WR-Ⅰ的粒度中值为75 nm,界面张力低至0.005mN/m,对钻井液的流变性影响小,有降滤失作用;通过快速吸附及封堵作用,该微乳液封堵率高达95％,对泥页岩井壁稳定具有突出作用;该微乳液具有优异的润滑作用,其极压润滑系数为0.051,滤饼粘附系数为0.138,可大幅度降低钻具与井壁、钻具与钻屑间的摩阻.%Micro-emulsion has been used in EOR as oilfield agent for decades,but not in drilling fluid.Wellbore instability and high friction have been encountered frequently during the drilling process in horizontal and directional sections.Common agents used in drilling fluid cannot meet the demands of plugging and lubrication at the same time.A nonionic microemulsion WR-Ⅰ was developed based on compound surfactants of Span-80 and Tween-80 aided with co-surfactant of nbutanol.The effect of the nonionic micro-emulsion WR-Ⅰ on the performance of drilling fluid was investigated,focusing on its plugging and lubricating properties.The results show that the nonionic micro-emulsion WR-Ⅰ has good performance including super-low interfacial tention of 0.005 mN/m and median size of 75 nm.It has little influence on the rheology of the drilling fluid and can lead to a small reduction in filtration loss.It can stabilize the wellbore of the shale section by quick adsorption and effective plugging with a blocking ratio of 95％.It has good lubricating property with an extreme pressure lubrication coefficient of 0.051 and a sticking coefficient of 0.138,which can effectively decrease the friction between drilling tools and wellbore as well as drilling cuttings.