Well drilling is a very technologically complicated process which consists of different stages and operations. Using different technologies to reduce well construction time is important to optimize well drilling costs. Geological complications can increase the time for pulling out the bottom hole assembly (BHA), condition the well, and running casing. Several studies have shown that nondrilling non-productive time (NPT) is significantly higher than actual drilling time. Casing while drilling (CWD) technology is a unique solution which helps to reduce well construction time in challenging formations while drilling and casing the well simultaneously. Conventional drilling process involves drilling and casing sections in separate operations. CWD involves integrating the casing run process with the drilling process. In casing while drilling, the bottom hole assembly is attached to the casing using a drill lock assembly (DLA). It is challenging to drill and case directional well because the BHA consists of specialized directional tools such as a bend motor, rotary steerable tools, measuring while drilling tools, etc. After reaching the required depth by using specialized tools, the directional BHA is retrieved and casing is cemented. Pilot test runs for directional casing drilling with retrievable bottom hole assembly technology were successfully conducted in Timano-Pechora region. Three directional wells were drilled with CWD technology on 244,5 mm (9 5/8") casing. There was no NPT during the operations. Casing while drilling technology alongside a steerable and retrievable BHA enabled the operator to drill a directional section in soft and unstable rock, hold trajectory according to plan and meet necessary dogleg severity, exclude the possibility of stuck pipe, and reduce well construction time by decreasing the number of wiper trips in open hole. The pilot experience helped to determine the advantages of casing drilling with a retrievable BHA in the specific conditions of the Timano-Pechora region. Tips for improvement and optimizations were highlighted for future reference of that technology in the region.
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