泥页岩地层油基钻井液封堵防塌技术研究与应用

Research and Application of Oil-Based Drilling Fluid Plugging and Anti-Collapse Technology in Shale Formation

泥页岩地层的水化作用会造成地层孔隙压力升高、岩石强度降低等变化,容易造成井壁剪切坍塌破坏。随着近几年页岩类油气田的大力勘探开发,超长的水平井段更是对泥页岩井壁稳定问题提出了新的考验。而油基钻井液的低滤失量(油相滤体)能有效解决泥页岩地层水化膨胀的难题。针对古龙区块泥页岩层理明显、孔隙分布多、微裂缝十分发育等特点,在油基钻井液中加入刚性、柔性、纳微米级和成膜的油基封堵材料,提高钻井液中固相颗粒的合理级配,进一步增加体系的封堵能力,可更有效地保证裂缝性泥页岩地层的井壁稳定,为泥页岩类油层的钻探开发提供了有力保障。并在古龙区块的钻井实施过程中,严格控制密度窗口,为钻探开发该区块的泥页岩类油层提供了有力的保证。

Hydration of shale formation will lead to the increase of pore pressure and the decrease of rock strength,which will easily lead to shear collapse of well.With the vigorous exploration and development of shale oil in recent years,the ultra-long horizontal well section has put forward a new challenge for the stability of shale oil well.However,the low fluid loss of oil-based drilling fluid(oil phase filter) can effectively solve the problem of hydration and expansion of shale formation.In view of the characteristics of shale in Gulong block,such as obvious stratification,abundant pore distribution and well-developed micro-fractures,the rigid,flexible,nano-micron and film-forming plugging materials are added to oil-based drilling fluid to improve the reasonable gradation of solid particles in drilling fluid and further increase the plugging ability of the system,which can more effectively ensure the wellbore stability of fractured shale formation and provide a strong guarantee for the drilling and development of shale oil.In the drilling process of Gulong block,the density window is strictly controlled,which provides a strong guarantee for drilling and developing shale oil in this block.