What happened: HPINMRIG LISTS DUE TO STABILITY INCIDENT The BCO transferred brine from the stbd colu

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EPT Wells HSE Learning Bulletin
Fountain No 311770 Location Brasil
Date 28 Oct 2008
What happened HPI-NM-RIG LISTS DUE TO STABILITY
INCIDENT- The BCO transferred brine from the stbd
column to the mudpits which caused the rig to be
somewhat heavy on the port side. Shortly
thereafter the Driller requested the BCO to level
the rig in order to center the pipe in the
rotary. In order to level the rig the BCO
intended to change the port bilge pump suction
from the high sea chest to ballast tank 3P (port
ballast tank 3), effectively continuing to
provide sea water service to the rig while
drawing water from 3P and leveling the rig
simultaneously. However the high sea chest valve
did not close which caused ballast tank 3P to
free flood through the open high sea chest valve.
The command to close the high sea chest was given
but it failed to close due to being
electronically isolated at the control panel. The
failure to close the high sea chest was masked by
a face plate (a computer screen pop-up window)
covering the valve display (green vs. red) for
the sea chest valve. As such the BCO did not have
a visual representation of the sea chest valve to
alert him the valve did not close. The rig
ultimately listed approximately 10-3/4 degrees
(port) and 3 degrees down on the bow before the
off tour BCO intervened and detected the open sea
chest. After the sea chest was closed, the port
bilge pump was used to pump the excess water from
tank 3P and the rig was brought back to level.

• Actions Implemented
• Reinforce the practice of closing all valves
  anytime there is an unknown change in trim until
  the cause can be ascertained
• Develop contingency plan for loss of ballast pump
  while being used for sea water service
• Management of Change required whenever a critical
  system is in a degraded state
• Conduct bi-weekly hands on ballast drills
• Develop revised protocol for immediate response
  to bilge alarms

• Preliminary Learning Points
• Communication to rig crews regarding the
  situation and instructions was lacking
• Response to a critical situation was inadequate
• No Management of Change performed for sea water
  pumps being out of service
• Permit to Work for replacement of stbd sea water
  pump did not address hazard associated with
  isolating pontoon
• Insufficient inventory of critical system
  replacement parts in country

This Learning Bulletin provides preliminary
learnings. A detailed investigation is pending.