龙深1井垂直钻井钻井液技术

DRILLING FLUID TECHNOLOGY OF WELL LONGSHEN 1 FOR VERTICAL DRILLING

龙深1井是龙门山前缘逆掩推覆构造带大园包构造上第一口深探井。该井上部地层倾角大,井斜控制困难,受断层影响地层破碎裂缝发育,存在井眼不稳定、井漏等复杂问题。为防斜打快,在Φ406井段使用了贝克休斯垂直钻井技术。在分析钻井地层特性的基础上,设计使用聚合物防塌钻井液稳定井壁,通过携砂剂、增粘剂配伍改善井眼净化水平,应用桥接堵漏和硬塞堵漏工艺提高井壁承压能力,保证了垂直钻井工具的井下安全和正常工作,钻井速度提高近5倍,井斜控制在1°以内。

The well Longshen 1 is a deep exploration well located at Dayuanbao structure of the overthrust nappe structure in front of the Longmen Mountain. The inclination angle of top formation is very big, so well inclination control is much difficult. Faults and natural fractures are abnormally developed, which result in disintegration and instability of formation. The most complex problem encountered is leakage of drilling fluid. During the drilling of 406mm section, the vertical drilling technique(VertiTrak)provided by Bake Hughes is employed. Based on analysis of formation characteristics, the other techniques were applied in the well, including using polymer anti-sloughing drilling fluids to stabilize sidewell, adding transporting agent and viscofier to improve hole cleaning, applying hard-plug circulation control method to enhance strength of formation and sidewell pressure resistance. These methods ensured the downhole safety and normal drilling process of vertical drilling tool, the drilling speed was increased about 2.7 times and the deviation angle was controlled within 2°.