HEWD in deepwater GOM
While drilling a well in deepwater Gulf of Mexico (GOM), an operator encountered pore pressure deviations, high mud weights, and the associated equivalent circulating density (ECD). The pore pressure issues required setting a 14-in casing string in the upper hole section and enlarging the next 12 1/4-in section—planned as a single-diameter drilling interval—to 13 1/2-in to incorporate an 11 7/8-in contingency liner if needed. Adding to the complexity of the interval, a 250-ft to 500-ft rathole was required at TD to stabilize a subsequent coring BHA run.
Flexible, on-demand underreaming
To avoid the time involved for extra trips to change out BHAs, the operator used the Rhino XC on-demand reamer. The Rhino XC reamer, which is designed for use in formations where HEWD is needed, enabled on-demand activation and deactivation of the underreamer multiple times as required while drilling. Because of its flexibility, the Rhino XC reamer can be placed anywhere on the BHA. The tool’s parallel tongue and groove design ensured that cutter blocks were deployed to the borehole enlargement diameter during activation and retracted when the reamer was deactivated.
Elimination of extra trips
With the cutter blocks activated, the Rhino XC reamer enlarged the 12 1/4-in section to 13 1/2-in for a total of 1,551 ft. After careful monitoring, the operator determined that the contingency liner was not required. The cutter block was then deactivated at the top of the coring section, and a 12 1/4-in borehole was drilled an additional 583 ft, providing the required stabilization for the subsequent coring run. The 2,188-ft interval was drilled in 62.5 hours, with no additional trips required.