Thunder Horse Drilling Riser Break - The Road to Recovery
- Bill Kirton (BP America) | Gary Wulf (BP America) | Bill Henderson (Resultants)
- Document ID
- Society of Petroleum Engineers
- SPE Annual Technical Conference and Exhibition, 26-29 September, Houston, Texas
- Publication Date
- Document Type
- Conference Paper
- 2004. Society of Petroleum Engineers
- 4.2.4 Risers, 1.7.5 Well Control, 7.2.3 Decision-making Processes, 4.5.7 Controls and Umbilicals, 2.4.3 Sand/Solids Control, 6.1 HSSE & Social Responsibility Management, 4.2 Pipelines, Flowlines and Risers, 1.6.1 Drilling Operation Management, 4.5.10 Remotely Operated Vehicles, 1.10 Drilling Equipment, 7.2.1 Risk, Uncertainty and Risk Assessment, 4.1.5 Processing Equipment, 1.6 Drilling Operations, 1.7 Pressure Management, 6.1.5 Human Resources, Competence and Training, 7.3.3 Project Management
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This article presents key learnings by BP's Wells Team on the Thunder Horse project after responding to a major incident - the break of the drilling riser on the Discoverer Enterprise drillship in May 2003 in the Gulf of Mexico. Even though BP has established policies for the immediate incident response phase and conducts training exercises, there is less focus on the later recovery phase. This paper increases the awareness of critical project management issues that may arise during transition from the response to recovery phase after a major incident.
At 3:59 a.m. on May 21, 2003, the drilling riser on the Discoverer Enterprise parted during operations at the BP-operated Thunder Horse field. With the riser under 2.1 million lbs of top tension, the parting produced a loud bang, and all on board the 103,000-MT vessel felt the subsequent sudden jarring. At the time, the crew had tripped about 200 ft out of hole after reaching a total depth of 24,901 ft (8,000 ft of departure) on the Mississippi Canyon (MC) 822 No. 6 well. A remotely operated vehicle (ROV) was deployed and found the riser parted at 3,200 ft subsea with drill pipe still intact.
Following the drill pipe deeper, the ROV then located the top of the riser at 5,100 ft subsea, supported vertically by the internal drill pipe, which was still connected to the surface (Fig. 1).
Diving to the ocean floor at 6,100 ft, the ROV next spotted the lower marine riser package (LMRP), located on top of the blowout preventer (BOP), where the riser and drill pipe had snapped off. Riser Joint No. 1 was seen resting against the BOP close to the control lines that function the stack. Fig. 2 shows the top of the LMRP after the riser break.
The BOP's deadman sequence functioned as designed and secured the well with the blind shears. No one was hurt, and the well was secure, but the initial scene was daunting. Approximately 1,900 ft of riser, still joined together, lay scattered around the drill center, either buried in the mud or resting on the seafloor and on the wellhead of the abandoned discovery well, MC 778 No. 1 (Fig. 3). Another 3,200 ft of riser remained suspended from the drillship, while yet another 900 ft of riser stood vertically above the seabed around the parted drill pipe.
Incident Response Phase
At 4:15 a.m. the first call reporting the incident came into Houston, immediately activating the Incident Command System. The Deepwater Development Drilling Manager assumed the role of duty Incident Commander. Within an hour, the Incident Commander, along with the Thunder Horse Wells Delivery Manager, mobilized the Operations Team and many of the on-call Incident Management Team (IMT) personnel. BP's existing Incident Command System protocols were used as a starting template, and the command structure was tailored to meet the unique subsea, salvage, and drilling needs of the riser parting incident (Fig. 4). This included in-house support by operations representatives from the drilling contractor, Transocean Inc., and partner ExxonMobil.
The operations room in Houston was staffed continuously for close to two weeks as the Team first assessed and stabilized the situation, and then began working on remedial operations. Critical issues revolved around ensuring that no one was injured during the subsequent unique operations, and avoiding further damage to rig equipment or wellheads with 3,200 ft of suspended riser, 900 ft of standing riser, and Riser Joint No. 1 against the BOP stack. Simultaneously, a small Incident Investigation Team was formed that was external to the operations team working the incident. The Investigation team members were chosen based upon their expertise in materials, riser design, stress analysis, riser operating practices, and incident investigation skills. Preservation of the failure incident scene was important to help determine the root cause of the failure. This team included members from Transocean and ExxonMobil. The decision was made early to have an integrated incident team in order to combine the critical knowledge of the companies involved and improve communications. This was very successful and resulted in the management of the companies being aligned during critical operations of the response and recovery phases.
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