Qin Guochuan, Xu Mingbiao, He Miao, Chen Kan
Petroleum Engineering College, Yangtze University, Wuhan 430100, China.
JiahuaKeji Co., Let., Jingzhou 434000, China.
ACS Omega. 2021 May 21;6(21):13817-13830. doi: 10.1021/acsomega.1c01361. eCollection 2021 Jun 1.
The poor lubrication performance of water-based drilling mud hinders its application in the drilling process of extended, reach horizontal wells. To overcome this shortcoming, polyaspartate (PA) and poly(ethylene glycol) (PEG) were used to improve the lubrication performance of the water-based drilling mud. The conventional performances, lubrication performance, and micro-image of antiwear steel balls of the modified water-based drilling mud were analyzed. The results show that the coefficient of friction (COF) of the water-based drilling mud mixed with 10% PA and 5% PEG was the lowest, reaching 0.094, the reduction rate of COF was 63.1%, and the drilling mud cake stuck factor was also the lowest. The addition of PA and PEG had no effect on the rheological properties of water-based drilling mud and also can significantly reduce the filtrate volume; the reduction rate of the filtrate volume reached 43.5%. All of these result from the synergistic effect of PA and PEG; they are adsorbed on the metal surface and the mud cake to form a lubricating film. At the same time, the lubricants also changed the appearance of the solid particles in the mud cake, which reduced the friction between the mud cake and the drilling tool. Moreover, effects of the influence of drilling mud properties on lubricants (alkali metal ions, pH, temperature, and drilling mud density) were examined. The water-based drilling fluid with the synergistic effect of PEG and PA shows similar lubrication performance as the oil-based drilling fluid and can meet the technical requirements of corresponding horizontal wells.
水基钻井液润滑性能较差，这限制了其在大位移水平井钻井作业中的应用。为克服这一缺点，采用聚天冬氨酸（PA）和聚乙二醇（PEG）来改善水基钻井液的润滑性能。对改性水基钻井液的常规性能、润滑性能及抗磨钢球微观图像进行了分析。结果表明，添加10%PA和5%PEG的水基钻井液摩擦系数最低，达0.094，摩擦系数降低率为63.1%，泥饼黏附系数也最低。PA和PEG的加入对水基钻井液的流变性能无影响，且能显著降低滤失量，滤失量降低率达43.5%。这些均源于PA和PEG的协同作用；它们吸附在金属表面和泥饼上形成润滑膜。同时，润滑剂还改变了泥饼中固体颗粒的形貌，降低了泥饼与钻具间的摩擦力。此外，考察了钻井液性能（碱金属离子、pH值、温度和钻井液密度）对润滑剂的影响。具有PEG和PA协同作用的水基钻井液表现出与油基钻井液相似的润滑性能，能够满足相应水平井的技术要求。
