CNOOC Drills Through ZOE with Near-Pinpoint Trajectory Control in East China Sea | SLB
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CNOOC Drills Through ZOE with Near-Pinpoint Trajectory Control in East China Sea

CNOOC Drills Through ZOE with Near-Pinpoint Trajectory Control in East China Sea

Published: 09/13/2017

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CNOOC successfully reached the TD with a center-to-center distance between planned Tie-in 0 MD, 0 TVD and actual trajectory of 2.14 m [7 ft]
CNOOC successfully reached the TD with a center-to-center distance between planned Tie-in 0 MD, 0 TVD and actual trajectory of 2.14 m [7 ft]
Location
China, Asia
Details

East China Sea

Borehole
12 1/4 in

Drilling interval
3,498- to 3,944-m
[11,476- to 12,938-ft] MD,
3,457- to 3,780-m
[11,342- to 12,402-ft] TVD

Zone of exclusion (ZOE) alert zone
678–3,919 m
[12,067–12,854 ft]

ZOE fail zone
3,711.83–3,874.68 m
[12,178–12,713 ft]

Background
CNOOC China Ltd. needed to drill a 12 1/4-in section to reach TD. However, the optimal trajectory required an azimuth of 0.09°—forcing the well design to plot through the ZOE and presenting additional accuracy challenges. Avoiding the ZOE meant that well tortuosity would increase tremendously. It would also force a much longer well path, increasing other drilling costs. It was determined that the PowerDrive Xcel rotary steerable system in gyro mode was the best solution.
Products Used
PowerDrive Xcel
Rotary steerable system

Maintain tight directional control through the magnetic zone of exclusion and monitor stick/slip, shock, and vibration.
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