CNOOC Drills Through ZOE with Near-Pinpoint Trajectory Control in East China Sea | Schlumberger
Tech Report
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

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

PowerDrive Xcel RSS successfully reaches TD while sustaining trajectory within 2.14 m of plan through ZOE region

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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]
Products Used

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