Blowout Preventer (BOP)
Installed on top of the well casing head, blowout preventers (BOPs) consist of various equipment, including high-pressure safety valves. The equipment associated with the system is engineered to shut off a well hole if necessary so that oil and other fluids do not escape. A BOP stack may contain annular preventers that form a seal between the drill pipe and wellbore. While these are typically on top of the stack, Ram-type systems inside it have rubber faced steel rams that seal the bore.
Other components include a choke line valve and a kill line valve. Choke manifolds are valves that circulate mud and provide an automatic response to prevent blowouts. Energy to run the system is provided by an accumulator that has regulator valves, pumps, compressed gas bottles, control manifolds and valves, and a hydraulic reservoir.
Use of BOPs
Blowout preventer valves are closed during well interventions. They can also be closed during in the case of overpressure, which can be caused by fluids entering the well bore. The system is typically operated via hydraulic actuators, controlled from remote locations. It is critical for the proper operation of the rig and the safety of crewmembers. Regular maintenance, refurbishment, and testing is a must, and daily tests are often conducted on the blow out system and other well functions.
Deepwater Horizon Accident
The rig, operated by British Petroleum, was located in 5,000 feet of water, 52 miles off the Louisiana Coast. In 2010, an accident and subsequent disaster resulted from a variety of malfunctions, both at a technical and human level. It was nearly complete in a mission to drill a 13,000 foot well under the Gulf of Mexico. In the accident, 11 people were killed. Causal factors, per an investigative report, included a loss of well control because relevant standards weren’t followed, deviation from plans for well abandonment, and a failure to react to indications of a control failure. The U.S. Chemical Safety Board found that control systems were improperly wired. Plus, a flawed well plan that didn’t include enough cement for the production and protection casing caused the blowout and subsequent oil spill.
After the accident, CNN reported that BOP failures are more commonplace than people realize. They occur in the ocean and on land too. The report described a natural gas well failure in Pennsylvania, in which a blowout preventer couldn’t stop gas from spewing into the air for up to 16 hours. Comparatively, the Deepwater Horizon rig spewed 60,000 barrels of oil per day into the Gulf of Mexico.
BOPs, along with other equipment, can be to blame in accidents. Multiple design flaws and mistakes can cause equipment to fail, making it challenging to prove who was liable for an incident. In many maritime accidents, vessel owners, captains, crew members, and manufacturers may be held accountable and be required to compensate accident victims and their families for injuries, medical costs, loss of income, and even wrongful death.