粉煤地层绳索取心钻进孔壁坍塌分析及处理

Analysis and treatment of hole wall collapse of wire-line core drilling in pulverized coal strata

摘要:

在甘肃省景泰县郭家台煤炭资源详查ZK30-1孔施工中，因强行提“水钻”造成了长孔段孔壁严重坍塌事故。分析认为坍塌地层粉煤层位多、累计厚度大，围岩结构松散、破碎是造成孔壁坍塌的地质因素；冲洗液性能与地层岩性不适应是主要技术因素。通过引入低粘强抑制冲洗液，扫孔过程中轻压慢转、小泵量循环，成功处理了孔壁坍塌，顺利终孔。煤田钻探施工对冲洗液性能要求严格，用绳索取心钻探粉煤对冲洗液性能要求更为苛刻，在冲洗液配制和钻进过程中尤其需要加强对其性能变化的监控。

Abstract:

Duiring the construction of ZK30-1 hole， a detailed investigation hole for coal resources in Guojiatai， Jingtai County， Gansu Province， serious collapse accidents happened in the long hole section caused by forcibly lifting the “water drill”. In this paper， the main reasons why the hole wall collapse were analyzed. Large cumulative coal thickness exists in the collapsed strata， loose and broken surrounding rock structure are the geological factors. The mismatch between the performance of the flushing fluid and the lithology of the formation is the main technical factor. By introducing low viscosity and strong suppression flushing fluid， gently pressing and slowly rotating during the hole cleaning process， and circulating with small pump volume， the collapse of the hole wall was restored， and the hole was successfully finished. Coal drilling construction has strict requirements for flushing fluid performance， and more strict when wire-line core drilling was used to extract core powder. It is necessary to strengthen monitoring of flushing fluid performance changes during mud preparation and drilling processes.