Drilling and completion technologies for extended-reach shallow CBM wells in Zhijin

To address the issues of lost circulation, big friction and difficult casing running while drilling surface holes in the Zhijin Block, drilling and completion technologies for extended-reach shallow coalbed methane (CBM) wells in the Zhijin Block were analyzed and successfully applied in Well ZP-4. These technologies include the selection of plugging approaches, optimized design of borehole trajectories, optimization of wellbore structures, selection of drilling fluid systems and optimization of completion strings. A technique of drilling with conductor pipes successfully solved the lost circulation problem. An optimized design of two-buildup trajectories allowed for accurately adjusting the vertical depth of landing points through near-bit geosteering. With this two-buildup trajectory design, no S-shaped trajectories were generated as single-buildup trajectory design did; friction was reduced and targets could be hit easily. An optimized design of completion strings enabled production casings to be successfully run in extended-reach shallow horizontal wells. Practices indicate that these drilling and completion technologies for extended-reach shallow CBM wells in the Zhijin Block solved the issues of lost circulation, big friction and difficult casing running while drilling surface holes and provided technical supports for further developing the Zhijin block with low cost and high efficiency.