Very severe problems during drilling were circulation loss and borehole collapse because of formation fracture growing, and drilling operation was very difficult.

该气田地层裂缝发育，钻井过程中井漏和井塌问题非常严重，钻井作业十分困难。

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Drilled formations are complex with unstable wall. Lost circulation, well kick, borehole collapse, diameter shrinkage, sticking and other complex situations often occur.

钻遇地层复杂，井壁稳定性差，井漏、井涌、井塌、缩径、卡钻等井下复杂情况频发；

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The problems of low drilling efficiency and low core recovery due to borehole collapse were solved with pulling in casing while drilling through using combined BHA with casing.

采用组合钻具进行跟管钻进，通过随钻跟入的套管保护孔壁，解决因钻孔垮塌导致钻探效率和岩心采取率低等技术难题。

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