杭锦旗区块锦58井区钻井液技术实践与认识

杭锦旗区块锦58井区钻井过程中普遍存在严重漏失及井壁失稳问题，为此，开展了该井区钻井液技术研究。在深入分析井漏和井壁垮塌原因及主要技术难点的基础上，从"预防为主"出发，优选钻井液处理剂、优化钻井液配方和性能，确定了随钻承压防漏堵漏和井壁稳定技术，以达到兼顾防漏防塌、确保安全钻进的目的。该技术在锦58井区的JPH351井、JPH393井和JPH404井等3口水平井进行了现场应用，大大减少甚至避免了漏失和井壁失稳问题，取得了显著效果。其中，JPH351井钻井过程中顺利钻穿刘家沟组易漏地层，堵漏时间缩短40%以上，减少了漏失次数，缩短了处理时间；石千峰组和石盒子组地层井壁稳定，平均井径扩大率仅为4.73%；水平段累计钻遇长泥岩段11段513.00 m，泥岩占比达35.92%；3 200.00~3 292.00 m泥岩井段揭开52 d后仍未出现井壁垮塌失稳问题。应用结果表明，随钻承压防漏堵漏和井壁稳定技术能够解决该井区的井漏与井壁失稳问题，保障高效安全钻井，具有推广应用价值。 

Development and Application of Drilling Fluid in the Jin-58 Well Block of the Hangjinqi Block

With high risks in drilling operations,the Jin-58 Well Block in the Hangjinqi Block frequently experiences severe lost circulation and borehole instability in drilling.To solve these problems,innovative drilling fluids have been developed for the Block.Through an in-depth analysis of root causes and key technical challenges related to lost circulation and sidewall collapsing,technologies with outstanding performances in pressure-bearing,lost circulation prevention,plugging and sidewall stabilizing were developed by selecting optimal treating agents in drilling fluids and by optimizing formula and properties of drilling fluids to ensure the safety of drilling operations.The newly-developed technology was successfully implemented in three horizontal wells(Well JPH 351,Well JPH393 and Well JPH404) of Jin-58 Well Block.Lost circulation and sidewall collapses were greatly decreased or avoided.For an example,the horizontal Well JPH351 penetrated the Jiujiagou Formation which is highly susceptible to lost circulation.The time required for plugging operations was over 40% shorter than those required in operations with conventional drilling fluids.In addition,to reduce the frequency of lost circulation,the time required to process these conditions is reduced dramatically.Sidewalls in the Shiqianfeng Formation and the Shihezi Formation displayed outstanding stability with average diameter expansion of 4.73% only.In the horizontal interval,11 intervals of mudstone with total length of 513.00 m,or 35.92% of total length,were penetrated.The 3 200.00-3 292.00 m mudstone interval maintained excellent sidewall stability 52 days after penetration.Research results showed the newly developed drilling fluids and matching technologies could effectively solve problems related to lost circulation and sidewall instability.These technologies have bright prospects in field applications at larger scales.