洞穴完井工艺在寿阳地区煤层气钻井中的应用

洞穴完井工艺包括钻井、完井、排水采气等工序，为提高煤层渗透率，最大限度的保证煤层气解析与运移，洞穴完井一般要求有效井径3-4m，及一定范围的破碎带。远东能源公司为开采寿阳地区15#煤层中的煤层气，部署了4口生产井．其井身设计为三开结构。钻井主要设备为T685WS顶驱车载钻机及多台不同型号的空压机，采用潜孔锤冲击钻进．以空气、空气泡沫为冲洗介质，钻进至15#目标煤层底板以下46m处完钻，然后利用可伸缩式扩孔器进行扩孔。在扩孔至距三开井底8～10m时．开始采用空气和清水憋压，通过瞬间释放压力，使煤层坍塌，如此反复，至造穴直径达到要求。由于严格按照技术标准及操作流程作业，采取的技术措施合理，4口井均已顺利投入生产，增产效果显著。可见该种洞穴完井技术的应用，不仅可以保护煤层原生结构及环境，并且还能减少煤层气射孔、压裂等环节的费用．对于煤层气井施工具有重要的经济意义。

Application of Well Caving Completion Technology in CBM Drilling in Shouyang Area

The well caving completion technology includes working procedures of drilling, well completion water drainage and gas extraction. To raise the coal seam permeability, ensure maximum CBM desorption and migration, effective well diameter 3-4m and certain extent of fracture zone are generally required in well caving completion. In order to mine CBM in No.15 coal seam in Shouyang area, the Far East Energy Company deployed 4 three hole-ins configured production wells. Main drilling equipments had T685WS top drive truck-mounted drilling rig and some different typed air compressors, used down-hole hammer percussion drilling with air, air foam as the flushing media. Drilling was completed at 46m below the No.15 target coal seam floor, and then used retractable reamer to ream the well. When reaming to 8-10m above the third hole-in well bottom, to use air and water to build pressure then released the pressure suddenly and repeated the operation to make coal seam collapsed to designed cave diameter. Owing to strictly operated in terms of technical standard, operation flow and reasonable technical measures taken, all the 4 wells have put into production with obvious increased effect. The well caving completion technology has major economic meanings in keeping coal seam original structure, environment production, CBM perforating and compression fracturing expenses reducing.