The oil rig was built by Hyundai Heavy Industries in South Korea, with an estimation of 560 million dollars. The oil rig was owned by Transocean and was under lease to British Oil Company called BP from 2001 until September 2013. Deepwater Horizon Rig explosion took place on 20th April 2010 at Macondo Prospect oil field, which is about 60 km away from Louisiana Coast. The explosion resulted in the sinking of the oil rig and death of 11 crew members. It also caused a huge offshore oil spill in the Gulf of Mexico, which is considered the largest oil spill in the world and also with huge environmental disaster effects in American history.
BP had built a new concrete cap in the core of the rig, which would contain all the natural gas released by the oil drill. The concrete had been mixed with nitrogen gas to speed up the curing process, this concrete cap was not installed and maintained properly. The disaster took place because of combination of poor installation of the concrete cap and enormous pressure of the deep ocean. On April 20, the concrete cap cracked, the natural gas shot up to the oil rig platform, where it ignited and exploded. The oil rig capsized all the oil began pouring into the ocean. According to official records, the oil rig was dropping sixty thousand barrels of oil per day into ocean. The total estimated volume of leaked oil was about 4.9 million barrels. In Louisiana Coast 2,200 tons of oily material was removed from the beaches. The oil spillage also had adverse effect on marine life. The infant dolphins were dying at six times the normal rate.
BP says that the accident was caused by the failure of seven different safety systems that were meant to prevent these type of incidents:
1) The cement at the bottom of the borehole did not create a proper seal, which in turn led the oil to pass through the pipes leading it to rig surface.
2) The mechanical valves which were designed to stop the flow of oil and gas at the bottom of the borehole failed. Due to this the reason the oil and gas traveled up the pipe to the surface.
3) The crew carried out different pressure tests to determine the proper seal of the well. The results of these tests were misinterpreted, and all the test engineers thought that the well was under control.
4) The crew at the surface would be able to detect a flow of gas towards the rig surface by looking onto its sudden increase in the pressure. This kind of incident occurred about 50 minutes before the rig exploded, but the crew misinterpreted it as a leak from the pipes.
5) Few minutes before the explosion, a mixture of mud and gas was pouring on the surface of the rig. The crew immediately attempted to close the valve and to activate the safety valve called as blowout preventer, but it did not work properly.
6) The gas alarm in the rig had failed to activate.
7) The blowout preventer worked on battery and closed-circuit connections, before the explosion the battery that controlled the safety valve was flat and also its switch was defective.
After the accident, President Barack Obama signed an executive order creating a commission to study the spill. The commission also recommended new safety rules and regulations, accountability standards, and environmental rules for drilling oil in US waters. According to the Bureau of Ocean Energy Management, the new set of rules were “the most aggressive and comprehensive reforms to offshore oil and gas regulations”.
People interested to know more about this disaster can watch a documentary, link is given below: