Incident

On April 20, 2010 at around 21:40 hrs, an uncontrollable flow of hydrocarbon fluids entered the Macondo well. The hydrocarbons breached all well barriers established to prevent uncontrolled formation fluid flow to surface. Rig crew were unaware of hydrocarbons in the well until the flow entered the marine riser.

The rig crew encountered mud overflow onto the rig floor and attempted to divert flow into the Mud-Gas Separator (MGS) at surface. Due to the limited rating of the MGS (only 60 psi) and high pressure flow from the well, the MGS eventually overflowed allowing mud and hydrocarbons to flow unabated. Well control equipment (Secondary Barriers) failed to contain the flowing well fluids as both hydraulic & electric control systems had been lost. The source of ignition is believed to be from the engine room as the engines were pushed into overdrive by the spreading hydrocarbon gas. Resulting explosions and fires de-stabilized the drilling platform and killed 11 members of the crew. The destabilized platform lost dynamic positioning and this forced the marine riser to detach from the rig fall to the sea floor. The Deepwater horizon drilling rig sank to the sea bed after burning for ~ 36 hours. Hydrocarbons continued to flow into the GOM for 87 days before the well was intercepted by a relief well; plugged and abandoned.

Aftermath

Following several unsuccessful attempts to seal the Macondo well, BP decided to adopt alternate techniques to cap the hydrocarbon flow at the seabed BOP stack directly.

ROV (Remotely Operated Vehicle) Surveillance had observed, identified and confirmed that the BSRs (Blind Shear Rams) had closed in an attempt to shear the drill pipe but had not sealed the well. The drill pipe was still inside the stack implying that the rams had only sheared the drill pipe partially.

BP in coalition with Transocean, Cameron and other industrial giants like ConocoPhillips & Exxon Mobil took a call to close all the other Rams on the BOP Stack with the hope that a seal could be achieved.

Following several unsuccessful attempts to seal the well, BP concluded that the Macondo well could not be sealed using the over worked BOP Stack on the seafloor. On May 5, 2010 all activities pertaining to the BOP stack had ceased and by September, 2010 the stack was raised off the seafloor.

Although several approaches were being carried out to establish a seal, in just days following the Macondo incident BP considered the concept of drilling a ‘Relief Well’ to intersect; plug and abandon the Macondo well. The initial estimate of time to drill a relief well to the required depth and specifications was ~ 100 days.

Contemplating the severity of the situation, government and industrial bodies accepted the proposal to drill a relief well even if a continued spill of ~ 100 days had to be sustained. The relief well method was collectively accepted as a high probable solution to seal the Macondo well.

Immediately after well plans had been approved by respective regulatory bodies, BP mobilized two rigs to drill two separate relief wells from a location close to Macondo (One was the primary well and the other was a backup kept on standby).

The Macondo well was killed permanently by 19th September 2010.

Way Forward

• The Industry responded with the development of 3 main frontiers to ensure integrity in all oil and gas wells:
  • 1. PREVENTION of Blowouts & Oil Spills.
  • 2. INTERVENTION in the most efficient manner.
  • 3. Effective RESPONSE to Emergencies with the Best Strategies to Monitor and Manage Issues.
• Review and Revision of Industry Policies and Procedures.
• Development of Updated Standards and Recommended Guidelines.
• Implementation of Specialized Bodies – Center for Offshore Safety (COS), Bureau of Safety and Environmental Enforcement (BSEE), Joint Industry Task Force (JITF), etc.