弱胶结地层水平井钻井技术探讨

水平井井眼轨迹控制的核心问题在于如何把握相对合理的全角变化率，而地层胶结状况（或地层物性）是影响全角变化率的关键因素之一。弱胶结地层水平井钻井主要存在全角变化率偏低、MWD信号传输不及时、底部钻具组合及钻进参数选择矛盾突出等技术难点。因此，应根据弱胶结地层的分布层位和厚度制定有针对性的技术方案和应急预案，宜使用大角度单弯动力钻具定向造斜钻进，而且钻具组合中要使用无磁承压钻杆和加重钻杆，尽量少用或不用钻铤，以保证井下清洁，提高井眼轨迹控制精度。以胜利油田埕52-平2井和草128-平4井为例，从钻井工程设计、钻井参数优选、底部钻具组合优化等方面对弱胶结地层水平井钻井技术进行了探讨。

Horizontal Well Drilling Technology for Weekly Consolidated Formations

The key point of horizontal trajectory control is how to control the inclination change, which is significantly impacted by formation lithology. In weakly consolidated formations, the technical challenges of drilling a horizontal well include lower rate of overall inclination change, improper MWD signal trans- fer, difficult to select drilling parameters and bottom hole assembly, etc. Therefore, corresponding technical considerations and emergency measures should be formulated based on zone depth and thickness of weakly consolidated formations. Mud motor with great bent is preferred to directional drilling. Nonmagnetic drill pipe and heavy weight drill pipe should be used in bottom hole assembly to replace drill collar to keep wellbore clean and improve accuracy of trajectory control. Wells Cheng52-Ping2 and Cao128-Ping4 were used as examples to illustrate the horizontal well drilling techniques in weekly consolidated formations, including drilling design, drilling parameter optimization, and bottom hole assembly optimization.