The explosion and fire that destroyed the Deepwater Horizon drilling rig in the Gulf of Mexico in April 2010 killed 11 crew members and triggered an environmental nightmare. Before the well was finally capped in mid-July, almost 5 million barrels of oil had been spilled into the Gulf, the National Oceanic and Atmospheric Administration reported, causing catastrophic damage for marine and plant life.
Federal investigators found that the disaster was the result of multiple mistakes made by oil company BP, including an improperly cemented seal on the well that allowed oil to leak, and the company's failure to perform up-to-par maintenance and safety tests and to adequately train the rig's crew, according to Time. In the aftermath of the incident, critics warned that drilling for oil more than a mile under water is inherently risky, since equipment must withstand intense pressure, and the methods used to cap leaks at lesser depths may not work. Nevertheless, six months after the accident, U.S. Secretary of the Interior Ken Salazar decided to allow deep-water drilling to resume, providing that operators comply with newly imposed, tighter safety standards.
What are these new measures, and have any other improvements been made to make offshore oil drilling a safer practice?
One of the causes of the Deepwater Horizon disaster was the failure of cement sealing, which lined the hole bored in the Gulf floor and held the pipe that goes down through the rig in place. New federal regulations require that an engineer certify that the cementing can withstand the pressures to which it will be subjected. BP says that in the future, it will not take its construction contractors' word that its wells are strong enough to withstand the extreme pressures to which they'll be subjected. Instead, the company will require laboratory testing of the cement used in the portions of wells that'll be under the most stress. This testing will be done by either a BP engineer or an independent inspector.
Some experts think BP and other oil drillers should go even further to strengthen wells. For example, oil industry engineers told Technology Review that the design of the Deepwater Horizon's well was fatally flawed because of BP's decision to install a continuous set of threaded casting pipes -- essentially, one long pipe -- from the wellhead down to the bottom of the well. That method seals off the space between the pipe casing and the bore hole drilled for the well, making it difficult to detect leaks that develop during construction, and allows gas from the oil deposit more time to build up and percolate, raising the risk of an explosion. Instead, critics want to see oil wells built in pieces, with each section of pipe cemented in place before the next one is installed. That slow, cautious method would enable builders to watch for leaks that might develop while the concrete is setting, and to fix them more easily. Unfortunately, it also would be costly.
On a deepwater oil rig, perhaps the most crucial piece of safety equipment is a device called the blowout preventer, or BOP. The BOP's function is to prevent gas and oil from rushing too quickly up into the pipe inside the rig, which can cause the sort of explosion that destroyed the Deepwater Horizon. Imagine pinching a rubber hose with your fingers to stop the flow of water, and you've got the basic concept, except that your hand would have to be more than 50 feet (15 meters) in length and weigh more than 300 tons, according to Newsweek. Instead of fingers, the BOP is equipped with a powerful tool called a shear ram, which cuts into the pipe to shut off the flow of oil and gas. Unfortunately, in the Deepwater Horizon disaster, the BOP failed to do its job.
Federal regulators hope to prevent those problems the next time around by requiring better documentation that BOPs are in working order, and better training for crew members who operate them. As added insurance, they now mandate that BOPs be equipped with more powerful shears, capable of cutting through the outer pipe even when subjected to the highest water pressure expected at that depth.
In addition, BP has announced that it will exceed federal requirements on its rigs in the Gulf by equipping its BOPs with at least two shear rams instead of one, and will also keep an additional set of shear rams on each rig as a backup. Additionally, BP says that whenever one of its undersea BOPs is brought to the surface for testing and maintenance, it will bring in an independent inspector to verify that the work is being done properly.
In deepwater oil drilling, robots are the roughnecks who get the most difficult jobs done. Oil companies have been using remotely operated vehicles (ROVs) -- basically, robot submarines that can descend to depths where no human diver could survive -- for more than 30 years, to do everything from turn bolts to close valves. Today's state-of-the-art ROV is a $1 million, box-shaped steel craft the size of a small car, equipped with mechanical arms that can lift up to a ton in weight. It's outfitted with video cameras that transmit live images from the dark depths to pilots in the control rooms of surface vessels thousands of feet above. At a typical Gulf oil rig, it's not uncommon to find half a dozen ROVs and several vessels for support crews working on various tasks.
But in the event of a disaster like the Deepwater Horizon blowout, ROVs become even more crucial. An unprecedented 14 robots worked on the emergency effort simultaneously. Some attempted to close the BOP's shear rams, while others hooked up hoses and plumbing, installed oil recovery devices and built the relief well to stop the gusher. Still others monitored the underwater plume of oil floating in the Gulf and gathered data on its effect on the Gulf's ecosystem, according to HuffPost.
The new federal regulations require that each oil rig have its own ROV, and crew members trained to operate it, so they can rush into action immediately in an emergency. Additionally, the feds now require BOPs to be equipped so that, in the event they fail to work, an ROV can take over and use its shear rams to shut off the pipe. To make sure that the robotic craft can work the BOP, the government is requiring more extensive testing of the machines, including having the ROV dive and operate shear rams at the sea bottom.
After the Deepwater Horizon exploded in April 2010, engineers struggled to figure out how to contain and stop the spill. As oil industry officials later admitted during Congressional hearings, they were unprepared to deal with a disaster a mile underwater, and so the emergency team was forced to use tactics improvised on the fly, from trying to use robots to force the BOP's shear rams closed, to lowering a 100-ton containment dome over the leaking well. It took them until mid-July to succeed in installing a device called a capping stack, which finally stopped the uncontrolled flow of oil. After that, they were able to perform a "top kill," in which they pumped mud and cement down through the well to block it, and then drilled a relief well to handle the remaining oil.
If there's a plus side to the catastrophe, it's that if and when another such deepwater blowout occurs, we'll be much better prepared. To deal with the Deepwater Horizon, the oil industry had to quickly design and create an assortment of new equipment, including a fleet of vessels modified to collect the oil spill, and a special system of pipes for performing a top kill and diverting oil flow. Additionally, engineers had to figure out how to utilize underwater robots to perform complex construction tasks, and had to become adept at using remote sensing technology to monitor conditions thousands of feet below on the Gulf floor.
Since the accident, BP has developed the Containment Disposal Project, a blueprint for how to use existing technology to respond quickly to oil spills based on the lessons of the Deepwater Horizon disaster. Additionally, a group of major oil drillers -- ExxonMobil, Chevron, ConocoPhillips and Shell -- have formed the Marine Well Containment Company, a new outfit that aims to develop more advanced systems for controlling blowouts.
The massiveness of the Deepwater Horizon spill forced the oil industry to try just about every conceivable method for removing oil from the Gulf and its shoreline: using ships to skim oil from the surface, controlled burning of the oil slick in open water and the use of chemical dispersants to break up the massive cloud of oil underwater.
While there's been controversy about the effectiveness of that effort, it provided experience and knowledge that will be invaluable in the event of another such accident.
For example, oil industry officials have learned how to combine information from a variety of sources -- satellite and aerial photography, thermal imaging, radar and infrared sensing, among others -- to detect the size of oil plumes and track their movement, which is essential to choosing the right method of cleaning up the mess. They've also built a new network of 26 radio towers outfitted with equipment for communicating with ships and planes, which will enable them to more easily coordinate response efforts to a future spill. In addition, the industry has beefed up its skimming capabilities, adding four modified barges known as "Big Gulp" skimmers, and setting up a system that can marshal nearly 6,000 local commercial fishing vessels to join in skimming operations. However, some of the other methods used to deal with the April 2010 spill remain controversial. While setting fire to oil removed as much or more of the spill as skimming, officials remain concerned about health risks from the resulting air pollution. The effectiveness of the approximately 2.5 million gallons of chemical dispersants used in the Gulf remains unclear, and there are nagging questions about the possible long-term health and environmental effects of the chemicals.
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