North Sea 1988

 Problem: On July 6, 1988 the Piper Alpha Platform was destroyed by gas explosions and fires. The platform is situated in 472 ft of water with 36 drilling slots of which 25 were active producers, 8 water injectors, and 3 wells shut-in. A development was being drilled at the time of the accident but was unrelated. The cause was attributed to a natural gas leak around the gas compression module. The gas ignited setting off a series of explosions and fires which totally destroyed the topside of the platform with the exception of the wellbay modules and the flare booms. Seven wells were potentially identified by Red Adair firefighters as burning. The wells were burning in pairs making it difficult to tell if only one of the wells was burning or both. All well trajectories went to the southwest from the platform.
Remedial Strategy: The primary method would be to control the leaking wells by surface control methods. Primary method was to insert inflatable packer into the tubing of the flowing wells then pump sea water down the tubing to stop the flow. Relief well(s) would be utilized as a backup. Three semi-submersibles were available for this effort. A plan was made to start a relief well for each of the three pairs of burning wells from a location such that a corresponding relief well could intersect any one after further identification was made by the firefighting teams.
Special Services: John Wright, as Eastman Christensen Relief Well Manager, coordinated the intersection team for this relief well.
Challenges: The project was complicated by the following:
  • Identification of the exact blowout wells on the platform was initially not possible.
  • Extreme political pressure and trauma from the deaths of 167 men on the platform.
  • Design and execution of a relief well program had to be performed immediately.
  • Borehole position uncertainty on the primary target well was very high.
  • The surface location of the relief well, already spudded, was not in an optimum position for the blowout target subsequently identified.
  • Rigging up a high rate kill manifold for a semi-submersible relief well had not been done before.
Results:
  • A Relief Well team was quickly assembled into intersection and kill units.
  • Three Relief Well designs were developed, only one was spudded.
  • Unique intersection plan devised to overcome high positional uncertainty.
  • The relief well was drilled as planned.
  • On July 29, 1988 control of P1 was gained from the surface and the relief well was cancelled at a depth of 5869 ft, approximately 2 days from the target.