宁夏灵武幅、磁窑堡幅综合地质调查LS01孔冲洗液护壁技术

Drilling fluid wall protection for the comprehensive geological survey Borehole LS01 for the Lingwu and Ciyaobao map sheets in Ningxia

摘要:

宁夏灵武幅、磁窑堡幅综合地质调查LS01孔设计深度800 m，钻探过程中钻遇200余米第四系未胶结松散地层，主要有砾石（漂砾）—粗砂—中砂—细砂互层，钻孔护壁难度大，容易发生掉块、塌孔事故，取心困难；进入第三系钻遇清水营组紫红色泥岩，地层造浆且易打滑；进入白垩系宜君组，钻遇365.91 m的破碎砾岩，地层松散破碎，钻进过程易卡钻，回转阻力大，回次进尺少，进尺慢。根据类似钻孔施工资料及地层情况最终采用成膜护壁冲洗液，钻进过程中穿过多层复杂地层，成膜护壁冲洗液在破碎砾岩孔段起到了很好的护壁效果，没有出现掉块、塌孔事故；岩心采取率满足地质设计要求，全孔平均采取率达到95.89%；节约了套管下入深度，终孔深度800 m，终孔口径124.00 mm。

Abstract:

The LS01 hole for comprehensive geological survey of Lingwu and Ciyaobao has a designed depth of 800.00m. During the drilling process, more than 200 meters of Quaternary unconsolidated loose strata was encountered, mainly gravel (boulder)-coarse sand-medium sand-fine sand were interbeded. It was difficult to drill and protect the borehole wall, and prone to have blockage and collapse incidents which made difficult coring. When entering the Tertiary system, the purple mudstone of Qingshuiying formation was met, and the stratum was slippery and produced mud; when entering the Cretaceous Yijun gravel formation, drilling encountered 365.91m broken conglomerate, loose and broken, prone to leading to sticking, high rotatory resistance, less footage per run, and slow advance. In reference to similar borehole drilling data and formation conditions, the film-forming wall-protecting drilling fluid was finally adopted. During the drilling process, the film-forming wall flushing fluid played a good role in drilling through multi-layers of complex strata and provided good wall protection over the broken conglomerate hole section without falling stones and hole collapse accidents. The overall core recovery rate reached 95.89%, meeting the requirements of geological design, which saved casing material. The final hole depth was 800.00 meters, and the final hole diameter was 124.00mm.