The operator set challenging rate of penetration (ROP) targets on a six-well campaign in the Norwegian Sea, with total depths between 6000 and 7000 m (19,500 to 22,750 ft) and initial targets of 70 m/h (17.5-in. interval) and 120 m/h (12.25-in. interval). To support these ROPs, the cuttings and slops management system should provide higher conveyance and storage capacities than typically observed during drilling operations. When specified ROPs were achieved, targeted rates increased on subsequent wells.
Collaboration among the operator, rig crews, and service provider was important to operating the high-volume cuttings management system. Adequate transfer and storage capabilities were essential on both the rig and vessels delivering waste to shore for disposal. The final configuration included the following components:
2 × 16-in. Conveyors, each feeding 2 pneumatic cuttings collection/transfer units
11 High-capacity, nonplugging storage tanks
1 Flexible hard-pipe system for simultaneous transfer to/from storage tanks
2 Cuttings transfer hoses for simultaneous discharge to vessel
1 Modular slop treatment unit
Cuttings transport tanks on the vessel
On the final well, ROP targets increased to 130 (17.5-in.) and 230 m/h (12.25-in.). Operating at 80 to 90% capacity, the system managed up to 60 mT of cuttings per hour. A total of 8959 m3 slops was treated, resulting in the overboard discharge of 8769 m3 treated water (oil-in-water concentration was 11.9 ppm), and waste volume sent to shore was reduced by 98%. The drilling program was completed 250 days faster than planned, and wells were delivered for production one year earlier than planned. The reduced time allowed the operator to drill a seventh well within the timeframe allotted for the original six-well program. Achievements of the seventh well continue to exceed expectations.
Close collaboration between the operator and personnel in the service company’s integrated rig team made this possible. Equipment operators continually optimized the process and delivered a high level of adaptability while ROP targets increased. This project set new standards for drilling performance on the Norwegian continental shelf.
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