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Gulf
of Mexico Region Spills ≥ 50 Barrels (2,100 gallons) – 2004 March 8, 2004 – Shell Offshore, Inc.
Remarks: On the H&P205 platform rig at the Ram Powell Tension Leg Platform (TLP) in Viosca Knoll 956, the driller gave the direction to line up the process tank to utilize the degasser. The posted schematic was incorrect. The pit hand shifted the "Actuator" handle which was incorrectly labeled "Degasser" in the schematic and caused an inadvertent discharge of 165 barrels of 10.5 ppg 58% Novaplus synthetic-based mud (SBM) through the shut line. A contributing cause was that the gang box was located out of the line-of-sight of the valves being operated precluding simple visual verification. It is estimated that the lost SBM contained approximately 95.7 barrels of Novaplus synthetic base oil. OCS Report: MMS 2004-048 NRC Report: 715384 April 11, 2004 – BHP Petroleum Company Inc.
Remarks: The ship was blown off location to the edge of the dynamic positioning watch circle 283 feet from the wellhead location and the Emergency Disconnect Sequence (EDS) was initiated. Approximately 60 seconds after EDS was initiated the Lower Marine Riser Package (LMRP) was successfully disconnected. Approximately 1,830 barrels of 14.5 ppg 56.5% Accolade synthetic-based mud (SBM) was discharged to the sea when the LMRP was disconnected from the BOP stack. The causes of the event were: the dynamic positioning system had been set up to prioritize heading rather than location; the on board weather radar had not been set to monitor extreme cells; drift off simulations did not match the short powerful spring storm; and only four of the seven engines had been set on line to be available. It is estimated that the lost SBM contained approximately 1,034 barrels of Accolade synthetic base oil. NRC Report: 718579 June 6, 2004 – Dominion Exploration & Production, Inc.
Remarks: After running a 9 7/8" liner at night while POOH (pulling out of hole) with running string and filling up hole with mud, a loss of 240 barrels of 77% Novaplus synthetic-based mud (SBM) was detected the next morning. The causes of the release were a faulty valve in a "Tee" in the mud transfer system located in the direct overboard line; and several procedural deficiencies. It is estimated that the lost SBM contained approximately 184.8 barrels of synthetic base oil. NRC Report: 724112 July 31, 2004 – Shell Offshore, Inc.
Remarks: The Garden Banks 341 Habanero Well #2 is a subsea well that produces to Shell's Auger tension leg platform (TLP) located in Garden Banks 426 9-12 miles away. To control gas freezing and gas hydrate problems in the Habanero Well #2, methanol is injected on a daily basis via two one inch umbilical supply lines from the Auger facility to the well. Shell operator personnel aboard Auger discovered abnormally low levels in their methanol tank on July 31, 2004. The Habanero well was shut in as well as the methanol injection until the source of the methanol leak was isolated and repaired. The total volume of methanol released was estimated to be 202 barrels. NRC Report: 730565 August 10, 2004 – Mariner Energy, Inc.
Remarks: Rig personnel were in the process of cleaning out one of the mud storage tanks on the Diamond Ocean America drilling rig. There was a miscommunication between the rig crew as to what the contents of the tank were and 895 barrels of 60% Novaplus synthetic-based mud (SBM) were inadvertently dumped overboard. The causes of the release were the miscommunication; failure to follow established procedures; and the system for monitoring the tank's contacts was out-of-service for repairs. It is estimated that the lost SBM contained approximately 537 barrels of Novaplus B synthetic base oil. NRC Report: 731375 Hurricane Ivan made landfall near Mobile, AL on September 15, 2004. Formal investigations were not conducted. Hurricane Ivan pollution volumes are generally operators' estimates of petroleum products (and in some cases chemicals) stored in/on structure prior to storm which had not been recovered as of Spring 2006. Some of these products may have been subsequently recovered. October 5, 2004 – Shell Exploration & Production Co.
Remarks: The operator reported to the NRC a release 5,310 gallons (126.4 barrels) of Baker Product 4394 Hi-M-Pact hydrate inhibitor of which 3,186 gallons (75.9 barrels) were spilled into the Gulf of Mexico. NRC Report: 737459 October 21, 2004 – Murphy Exploration & Production Co.
Remarks: A clogged hose on the Nabors 200 drilling rig caused synthetic-based mud (SBM) to be backed up into the hose and out of the tank. Approximately 180 barrels of 60%** SBM was released into the Gulf. It is estimated that the lost SBM contained approximately 108 barrels of synthetic base oil. NRC Report: 739031 THE SPILLS BELOW ARE DRILLING MUD SPILLS WHERE THE POLLUTION, SYNTHETIC BASE FLUID VOLUME, IS LESS THAN 50 BBL, BUT THE TOTAL MUD VOLUME WAS 50 BBL OR GREATER April 10, 2004 – BHP Billiton Petroleum (GOM) Inc.
Remarks: LESS THAN 50 BBL POLLUTION (but total mud volume greater than 50 bbl). A fire occurred on the GSF Explorer drill ship that was most likely caused by a breakdown of insulation while it was located in Atwater Valley 618. The fire was extinguished by the 3 personnel in the area using hand held CO2 extinguishers. These three personnel suffered smoke inhalation, they were checked out by the medic and released to return to work. The rig's fire team was mobilized and they ensured the fire was extinguished and cleared the area of smoke. The fire had caused a complete power outage on the rig disabling the dynamic positioning (DP) system. It was considered a disconnect was imminent and the decision was made to displace the riser to seawater. This was performed with the diesel power cement unit. The riser displacement was relatively inefficient due to the low pump rate and 285 bbl of the 2,200 riser volume was left on the riser. The rig was able to regain DP control so the riser was not disconnected. When the riser was displaced back to mud, 202 bbl were captured at the surface. A total of 83 bbls of 12.5 ppg synthetic-based mud (SBM), of which 57% or 47.4 bbl was synthetic base oil, was discharged to the sea during the displacement process. NRC Report: 718609 May 4, 2004 – BP Exploration & Production, Inc.
Remarks: LESS THAN 50 BBL POLLUTION (but total mud volume greater than 50 bbl). The Boost line had not been tested per plan. During drilling operations, loss indications in pit sensors occurred as commenced pumping down the boost line. A leak was discovered at 5607 ft bsl at a boost line stab seal. Reported loss of 75 bbls of 51.5% Accolade 13.9 ppg synthetic-based mud (SBM). It is estimated that the lost SBM contained approximately 38.6 barrels of synthetic base oil. NRC Report: 720737 NOTES: Synthetic Oil Fluids*: In deepwater drilling, synthetic-based muds (SBM’s) are preferred over petroleum oil-based muds (OBM’s) due to the SBM's superior performance properties. The synthetic oils used in SBM’s are relatively non-toxic to the marine environment and have the potential to biodegrade. 60%**: Indicates that for a synthetic-based mud release, the exact percentage of volume of synthetic base oil to total volume of mud released was not available and 60% was used as a reasonable approximation. Privacy | Disclaimers | Accessibility | Topic Index | FOIA Last Updated: 06/24/08, 02:42 PM
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