Research and application of strong plugging oil-based drilling fluid technology for Anye 2-3HF well
Aiming at the frequent occurrence of well wall instability in Longmaxi formation during the devel-opment of Zheng'an shale gas,the seriousness of block dropping,and the frequent causing of stuck drilling accidents,etc.,through the study of lithological characteristics of Longmaxi formation and the analysis of the mechanism of well wall instability,it has been determined that the strengthening of blocking properties is the key point for the research,development and improvement of the technology of oil-based drilling fluids in the Zheng'an workover area.Through the research of key treating agent emulsifier and blocking agent,the formu-lation of strong blocking oil-based drilling fluid system was formed and its performance was evaluated.The re-sults showed that the drilling fluid had good immediate and long-lasting blocking performance,effectively in-hibited the hydration and dispersion of rock cuttings in Zheng'an block and expansion and shrinkage,had good resistance to rock cuttings contamination in Zheng'an area,and the overall performance was basically stable within 20%of the rock cuttings,and its comprehensive performance was much better than that of con-ventional oil-based drilling fluids,which could satisfy the demand for wall stabilization in Zheng'an area.Meanwhile,the strong blocking oil-based drilling fluid was tried in Anye 2-3HF well,and compared with the drilled neighboring wells,there was no well wall instability in the three open sections,which improved drilling efficiency,and provided a certain reference direction for the optimization and improvement of the drilling fluid in this work area.
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