长垣东部深井井壁失稳及技术对策

大庆油田在长垣东部深层油气田勘探开发过程中存在井眼不稳定问题。在对深层失稳井段资料调研的基础上，开展了易塌地层泥页岩水化膨胀及分散特性评价以及比亲水量研究。通过泥页岩--试液模拟作用的化学位差反渗透实验以及压力传递实验等，探讨了不同条件下泥页岩水化应力变化规律。利用井壁稳定性模拟实验装置（SHM仪），评价了不同钻井液防塌效果。理论分析和实验表明，当使用水基钻井液在复杂泥页岩地层钻进时，如何控制泥页岩压力传递和流体侵入是解决泥页岩井壁不稳的技术关键。使用长垣东部深层泥页岩与硅酸盐钻井液作用的实验表明，硅酸盐钻井液能显著降低泥岩渗透率，阻止钻井液滤液与孔隙压力的传递，改善膜效率，有助于充分发挥化学位差诱导的反渗透防塌作用效果。

RESEARCH ON BOREHOLE UNSTABILITY OF DEEP WELLS IN THE EAST CHANGYUAN AREA OF DAQING OILFIELD AND RELATED TECHNICAL MEASURES

In recent years, the deep well borehole unstability problem has been very serious during oil field exploration and development in East Changyuan of Daqing Oilfield. Based on the investigation of the unstable wellbore data of deep wells, the hydration swelling and dispersion characteristics of the deep sloughing shales in East Changyuan have been evaluated, and specific hydrophilia have been studied. The hydration stress variation rules of shales under different conditions have been discussed, and the anti-sloughing effects of different drilling fluids have been evaluated. Both the theoretic analysis and experimental results show when water-based drilling fluid is used to drill through shales, good control of pressure transmission in shales and fluid influx are key to the elimination of shale wellbore unstability. And silicate drilling fluids can remarkably reduce the permeability of shales, prevent drilling fluid filtration and pore pressure transmission, and improve membrane efficiency, which will be helpful for producing chemical potential differential induced anti-sloughing effects.