山西河东煤田石楼北区块NSL05井煤层气钻井施工工艺

石楼北区块位于鄂尔多斯盆地东缘。该区域表土层松散易坍塌，在以往的钻探施工中，地层中不同程度的存在涌水或者漏失情况。太原组第三层灰岩可钻性较差，取心作业中频繁发生钻头被堵死的情况。为了解决以上问题，缩短施工工期，对钻具组合和钻井参数进行了调整，采用四翼PDC钻头、直螺杆的钻具结构；取心作业主要采用绳索取心，采用①215．9mm的取心钻头代替该区以往的016．9mm钻头，利用Φ127mm钻杆作为绳索取心工具的运行通道，并采用自行研制的内外管总成和内管取心工具．保证了取心效果；将钻头水眼更改为12mm×2＋14mm＋16ram的组合方式，有效保持了钻孔内的清洁，避免岩屑重复破碎，进一步提高钻进效率。同时介绍了钻探施工程中设备的配套、钻井液的配制、钻井技术参数的选择等。结果表明：该井取心岩心总收获率为92．15％，其中8#煤心质量总采取率为93．50％；井斜3°10′，全井水平位移44．17m，最大全角变化率耋1．1。／30m。对该区煤层气井钻探施工有很好的借鉴作用。

NSL05 CBM Well Drilling Technology in Shilou North Block,Hedong Coalfield,Shanxi

The Shilou north block is situated at the eastern margin of Ordos Basin. The overburden in the area is loose and easy to col- lapse; varying degrees of water gushing and circulation loss have been happened in past drilling operations. The No.3 limestone in Tai- yuan Formation has poor drillability, bit bailing happened frequently during coring. To solve above issues and shorten operation period, carried out regulations for drilling assembly and drilling parameters, thus using 4-wing PDC bit, frank screw drills, wire-line coring, 215.9mm coring bit replacing q~169mm coring bit, dP127mm rod as wire-line coring channel and self manufactured inner, outer tube assembly, inner tube coring tool have ensured coring effect. Bit nozzle has been modified into 12mmx2＋ 14mm＋ 16mm array mode, thus effectively kept borehole clean, avoid cuttings repeatedly crushing, raising drilling efficiency a step further. Meanwhile, the equipment combinations, drilling fluid formulation, parameter selection during drilling operations have been introduced. The result has shown that total core recovery of the well is 92.15%, in which, total core recovery of No.8 coal is 93.50%; well deviation 3~10＇, horizontal displace- ment 44.17m, maximum dip angle rate of change ~l.l~/30m. The study is a nice reference for CBM well drilling operations in the area henceforth.