Changes

- Especially in harder rock the method is slow (weeks, rather than days).尤其当岩石更为坚硬时，这一钻井方法较慢（需要几周，而不仅是几天）。 <br>

- When temporary casing has to be used, the time taken driving and removing it can significantly increase drilling time.在必须使用临时套管的情况下，花费在的装卸套管的时间会大量增加钻井时间。<br>

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