湘西北复杂构造区雪峰山先导孔钻进技术

Drilling technology for Xuefengshan pilot hole for shale gas geological survey in Northwest Hunan

摘要:

雪峰山先导孔是部署在湘西北沅麻盆地麻阳向斜的一口页岩气地质调查井。钻遇地层松散破碎、裂隙发育、软硬互层等，钻进中极易出现漏失、卡钻、埋钻、岩心掉落等孔内复杂情况，严重影响了钻进效率。针对钻进过程中遇到的复杂地层及钻进技术难点，如裂隙发育地层钻井液漏失和涌水问题、松散破碎地层岩心采取问题、水敏性地层孔壁稳定性问题，提出了针对性的解决措施，包括：改进取心钻具，采用不提钻换内钻头拦簧护心绳索取心钻具；优化钻井液配方，采用微泡沫钻井液以及膨润土+褐煤树脂+广谱护壁剂Ⅲ型+抗高温抗盐降失水剂+石灰石粉的钻井液配方；采取针对性的施工管理措施。提高了钻进效率，钻井质量满足地质要求，有效地完成了钻井施工任务，为同类型页岩气调查井的钻井施工提供技术参考。

Abstract:

The Xuefengshan pilot hole is a shale gas geological survey hole deployed in the Mayang syncline in the Yuanma Basin in Western Hunan. This paper introduces the engineering and geological conditions of the borehole with focus on the drilling and completion technology. The complex formations and drilling technical difficulties encountered during the drilling process are also summarized and analyzed with specific solutions put forward for different drilling difficulties. The solutions mainly include improving drilling and coring tools， adopts wire-line coreing tool that does not lift the drill to replace the inner drill bit with a spring core protector cord. Micro-foam drilling fluid and a drilling fluid formula of bentonite+lignite resin+broad-spectrum wall protectant type III+high temperature and salt resistance fluid loss agent+limestone powder are used. Developing the relevant management measures. As a result， drilling efficiency has been improved， drilling quality has met the geological requirements， and the drilling tasks have been effectively completed. It is desired the drilling experiences can provide technical reference for drilling of similar shale gas survey boreholes.