Casing while Drilling (CwD) technology has become a favorable drilling technique and gaining attention among operators across the Asia Pacific region due to its field proven reduction in drilling flat time and as a solution to potential downhole problems. The non-retrievable CwD technique includes a drillable casing bit and float collar assembly attached to the lower end of the casing string. The entire casing string is driven by a surface drive system. Cementing can be carried out immediately upon reaching total depth. A conventional drilling assembly is subsequently deployed to drill out the casing bit and next hole section, without the requirement of a special drill-out trip.

Previous successful CwD operations for top hole sections of offset wells in Malay–Tho Chu Basin offshore Vietnam, have encouraged the operator to further improve the drilling efficiency. The operator planned to install 13-3/8″ conductor casing utilizing CwD techniques in similar lithologies with an even more efficient, safer, and automated surface drive system. An automated surface drive system was selected to replace the conventional manually operated casing drilling spear which was used in the previous campaigns.

The automated surface drive system combines conventional casing running equipment into a single unit, allowing string rotation and push-down while running, circulating, or reciprocating. The system's integrated measuring shaft gives more precise torque readings when making up a connection.

This paper discussed the first case history of successful planning and implementation of CwD with the automated surface drive system in Vietnam. Emphasis is placed on the entire process from the pre-job engineering planning stage until project execution, as well as the improved drilling performance and outcomes.

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