白涧铁矿ZK27A07孔下套管跑管事故处理

在河北省沙河市白涧铁矿勘探ZK27A07钻孔施工中，钻遇2个含承压水大型溶洞。在下入?89 mm套管过程中，发生了脱扣跑管事故。事故处理过程中又发生了套管二次坠落和打捞工具多次折断掉入孔内事故，在溶洞内造成了多个活动事故头叠加。最终采用混凝土浇筑通过自然绕障的方法，成功处理了此次跑管事故，使钻孔免于报废。本文详述了事故处理的全过程，并通过对事故发生经过、原因进行认真分析，给出了在套管柱超长超重的情况下安全下管的具体方法，同时探讨了有多个含承压水溶洞钻孔内如何实现对护壁套管柱可靠封固的问题。

Treatment of casing unscrewing in ZK27A07 hole of Baijian Iron Mine

Two large karst caves containing confined water were encountered during drilling of ZK27A07 borehole for Baijian iron ore exploration in Shahe City， Hebei Province. In the placement process of ?89mm casing， the casing unscrewed and fell downhole. In the process of accident treatment， the casing fell downhole again， with fishing tools breakingoken and falling downhole for several times， forming a superposition of multiple movable accident heads in the karst cave. We successfully handled the casing falling accident by casting concrete and natural by-pass drilling， so as to avoid scrapping the drilling hole. In this paper， the whole process of accident treatment is described in detail. Through careful analysis of the process and causes of the accident， the specific method is presented for safe placement of the casing string with excessive length and overweight. At the same time， how to realize reliable borehole wall sealing with the casing string in drilling through multiple karst caves containing confined water is discussed， which is intended to provide reference for similar projects.