Gulf of Mexico 2000

Problem:   A shrimp boat collided with a single caisson oil well bending the conductor to a 30° angle with the seabed. All casing strings and tubing were cracked and open to the sea above the SSSV. The well presented an environmental hazard and would not be possible to intervene if the SSSV were to fail short of drilling a relief well. The well had to be made safe.
Remedial Strategy:  Recovery was planned in two steps. First drill a relief well to intersect the problem well above the production packer @ 9850 ft tvd. A notch would then be milled into the 7-5/8� casing and mud circulated to the seabed followed by a 600 ft cement plug. This would seal the annulus and protect the well from an annular blowout. A 60� caisson would then be driven around the damaged wellhead to a depth below the casing breaks. The damaged casing strings would be removed and the 7-5/8� and tubing tied back to surface. The tubing could then be bullheaded with kill fluid followed by cement for P&A. The relief well would standby to severe the tubing and kill the well if a problem occurred at surface.
Special Services: John Wright Company (JWCO) was contracted to supervise the special services for the relief well to include: pre-planning, on-site supervision, directional drilling, surveying, casing detection, intersection and kill hydraulics. Well Flow Dynamics provided hydraulic modeling, Vector Magnetics provided electromagnetic ranging services and Gyrodata provided gyro surveys. All companies worked together with JWCO to create a single special services team.
Challenges: The project was complicated by the following:
  • The intersection depth was tvd dependent with a short section above the production packer acceptable for intersection.
  • Timing was critical to coordinate the surface operations with the relief well intersection. Delays on the relief well would be costly due to the combined operations with the surface team resources on standby.
  • It was desired to cut a notch in the casing but not cut the tubing inside. This required specific incident angles and custom mill design to minimize this risk.
  • The project was completed according to plan without significant problems or delays.
  • The special services team was integrated seamlessly with the drilling team to create an effective and efficient operation.
  • The intersection was executed using a casing whipstock due to a motor failure and subsequent fish at the casing shoe.
  • The notch was cut in the casing using a custom mill on a standard steerable mud motor.
  • Mud was circulated to the seabed and a cement plug set as per design.
  • The surface operations proceeded as planned and the well was plugged and abandoned without further incident.