Deepwater Horizon Blowout Animation

On April 20, 2010, 11 workers were killed and 17 seriously injured by an explosion at Deepwater Horizon, an offshore drilling platform located approximately 50 miles off the coast of Louisiana. The platform burned for two days and eventually sank, causing the largest oil spill in U.S. history and gas spewed from the seafloor, Deepwater Horizon had been drilling an oil well in 5,000 feet of water in an area of ​​the Gulf of Mexico known as the Macondo prospect. In 2010, the CSB launched an investigation to examine the technical, organizational and regulatory factors that contributed to the accident. During the investigation, the CSB made new findings about why a key piece of safety equipment, the Deepwater Horizons

blowout

preventer, did not managed to seal the well during the emergency.

These new findings help explain why the accident was so devastating and the CSB warned that other explosion prevention devices currently in use could fail in a similar way. Drilling an offshore well involves creating a path between the drilling platform and oil and gas reservoirs trapped beneath the seafloor. A deep well is drilled through layers of underwater rock and sediment. These rock layers may contain waste water, crude oil and natural gas under pressure, an unplanned flow of these fluids from the well into the well, known in the industry. As a kick, it can be dangerous without careful management, a kick can cause an explosion, the uncontrolled release of flammable oil and gas from In the well, an explosion can be catastrophic, as oil and gas reaching drilling speed They can quickly find a life-threatening ignition source or explosion on the drilling rig to prevent drillers from kicking the pump.

It dents mud called drilling mud into the well, creating a barrier between the underwater oil. and the gas and pipelines leading to the platform, if this mud barrier fails or is somehow removed, the safety of the drilling rig depends on a critical piece of equipment located on the seabed called a

blowout

preventer or Bo Q. The Bo P is a complex. Electrically and hydraulically powered device that is essential to control the well and in an emergency situation to prevent a disaster on the platform high above the sea surface, the Bo P is connected to the platform by a large diameter pipe called a tube. ascending if a kick occurs.

The blowout preventer is designed to prevent flammable oil and gas from rising up the riser to the drilling platform. This is done by sealing the area around the drill pipe known as the annulus. To do this, the team can manually close the pipe rams and donut-shaped rubber devices. Known as annular preventers, if those devices don't work, the last resort is a pair of sharp metal blades that form a blind-cutting ram designed to cut the drill pipe and seal the well. The blind shear ram can be activated manually or by automated emergency systems. at approximately 8:45 p.m.

On April 20, 2010, a kick occurred at the Macondo well, oil and gas entered the well undetected and eventually bypassed the blowout preventer and traveled rapidly up the riser toward Deepwater Horizon and the 126 people. shortly after 9:40 p.m. Drilling mud forced upward by rising oil and gas suddenly flew toward the platform. Crew members responded by closing the upper annular preventer on the Bo P; However, this did not seal the wellbore as expected and flammable oil and gas continued to flow into the riser. The rig then closed a Ram pipe, this successfully closed the annulus and sealed the wellbore, but tragically this It turned out to be only a temporary solution.

Oil and gas already above the Ram pipeline continued to flow inexorably toward the Deepwater Horizon at approximately 949 pm. flammable hydrocarbons found an ignition source the first explosions shown on Deepwater Horizon when oil and gas escaped from the riser onto the platform the pressure dropped in the annulus above the Ram pipe but at the same time the pressure in the drill pipe increased The drill pipe was substantially closed at the top, but oil and gas continued to flow from the reservoir below. After extensive analysis, the CSB concluded that this large pressure difference likely caused the drill pipe to buckle, essentially bending the tubing off-center inside the blowout preventer.

The buckling pushed sections of the drill pipe out of reach of the blind shear ram blades. This would eventually prove catastrophic with the drill pipe buckling, the explosion and subsequent loss of electrical and hydraulic power due to the attack likely activated an automated system in the blowout preventer known as the AMF Deadman which closes the blind ram and cuts the drill pipe. . This emergency system is designed to activate when electrical hydraulic pressure and communications from the platform are lost. The AMF Deadman system was operated by two redundant control systems in the Bo P known as the yellow pod and blue pod.

The redundancy was supposed to increase the reliability of the system in an emergency situation. The yellow and blue pods operated independently of each other and were Composed of identical closed computer systems and solenoid valve assemblies when activated, the solenoid valves controlled important functions of the Bo P, such as closing the Blind Cut Ram if electrical power to the platform was lost, happened on April 20, 2010 Both the yellow and blue control modules contained 27-volt and nine-volt backup batteries to power the emergency functions. The nine-volt batteries powered the computers that activated the solenoid valves that were powered by the 27-volt batteries;

However, evidence indicates that the blue capsule had been improperly connected at some point before the Bo P was lowered to the sea floor, causing the capsules' 27-volt battery to drain and making it impossible to operate the valve. blind cut Ram solenoid the night of the accident and inside the redundant yellow capsule the blind cut Ram solenoid had been miswired the solenoid valves were controlled by two coils of electrical wire These two coils were designed to work together generating a magnetic field strong enough to operate the valve, but inside the poorly wired solenoid valve, the two coils actually opposed each other leaving the valve paralyzed.

Only a third unplanned failure allowed the yellow capsule to operate overnight. of the accident one of the 9 volt batteries that powered the solenoid valves computer had failed as a result the affected computer system could not initiate the command to energize the miswired coil if both coils of the miswired and energized solenoid valve had been energized the two coils generated opposite forces on the valve, the solenoid valve would have remained closed and the blind shear ram would never have closed; However, the failed battery left one coil inoperable and most likely allowed the other coil to open the solenoid valve on its own, this in turn initiated the closure. of the blind shear Ram, this should have sheared the drill pipe and sealed the wellbore, greatly reducing the impact of the accident, but because the drill pipe was buckled and off-center within the blowout preventer, it became trapped and only It was partially cut with the failure of this.

As a last measure, there was nothing left to stop the massive oil spill and the destruction of the ring. During its investigation, the CSB identified a mechanism that likely caused the drill pipe to buckle at the time of the explosion. This mechanism is called effective compression, although effective compression had previously been observed as a hazard in other drilling operations, it had never been identified as a problem affecting drill pipe during well operations. Effective compression occurs because, although the pipe may appear perfectly straight, it actually has small curves and irregularities invisible to the observer. At first glance, along these curves, the side of the pipe that is curved outward is slightly longer and has more surface area than the other side when there is a large pressure difference between the inside and outside of the pipe. pipe occurred on April 20, 2010, the longer the side of the pipe experiences a greater bending force, eventually this force can become large enough to buckle even a heavy pipe.

This is an important finding, CSB researchers said because the same differential pressure conditions could occur on other drilling rigs even if a rig successfully shuts down one. While the CSB cautioned that this could make existing blowout prevention designs unusable, Less effective in emergency situations, in the case of the Deepwater Horizon accident, the kinked drill pipe prevented the Ram blind shear from sealing the well, oil and gas from the well flowed out of the kinked drill pipe. and in the Gulf of Mexico for 87 days it was reported that 5 million barrels of oil eventually spilled causing one of the worst environmental disasters in the history of the United States.