准噶尔盆地八区调整井高效安全钻井技术

准噶尔盆地八区乌尔禾调整井区是一个易漏易喷、复杂时率高、钻井难度大的老油气田。随着钻井井深的增加，钻井地质条件更加复杂，井漏、溢流的情况频繁，地层可钻性变差，水平位移的要求更严格，这些因素均不利于钻井速度的提高，钻井难度加大。在分析钻井复杂地质环境的基础上，针对钻井技术难题，利用了先进的方法提高地层压力预测的精度，确定合理的泥浆密度，实现平衡压力钻井。通过加强漏失规律和漏失机理的研究，采取有效的预防井漏技术，并结合桥塞堵漏的方法措施，有效地防止了井漏、井塌和溢流的复杂情况，在井深3050 m以上的堵漏成功率达到90%以上，固井质量优质率达到96%；结合科学化管理，制定切实可行的组织措施，复杂事故时率下降到3.52％,达到了安全高效的钻井目的。

HIGH-EFFICIENCY AND SAFETY DRILLING TECHNIQUES OF ADJUSTMENT WELLS IN THE EIGHTH REGION OF ZHUNGE'ER BASIN

The Wu'erhe adjustment well area in the eighth region of Zhunge'er basin belongs to an old oil field having great difficulties in drilling, such as being easy of mud-loss and blowout, being of high complex accident time ratio, i. e. the ratio of complex accident treating time to drilling time, and so on. Along with the increase in drilling depths, the drilling geologic conditions became much more complex, the mud-loss and overflow being frequent, the formation drillability becoming poor and the demand for horizontal displacement being more rigorous, which was unfavourable to raising drilling speed, thus increasing the difficulty in drilling. On the basis of analyzing the complicated drilling geologic environment and the drilling technical difficulties, the accuracy of predicting formation pressure was enhanced by applying the advanced methods, thus deciding rational mud density to realize balanced pressure drilling; and, by means of studying lost circulation law and mechanism, the complex circumstances, as mud loss, well slough, well overflow and so on, were effectively controlled by adopting lost circulation prevention methods and applying bridge plugging technique, the plugging-off success ratios at the well depths of less than 3050 m being over 90% and the factor of merit of cement job quality up to 96%. Because of realizing scientific management and drawing up practical and feasible organizational measures, the complex accident time ratio decreased to 3.52%, the aim of high-efficiency and safety drilling having been attained.