4.2 Deep Water Horizon

In the late spring and summer of 2010, the United States was dealing with one of the worst oil spills to date (6–8). It occurred in the Gulf of Mexico and involved the Deepwater Horizon drilling platform. The Deepwater Horizon was an offshore oil platform owned by Transocean Ltd (Transocean). The rig was drilling within the Macondo Prospect oil field approximately 50 miles southeast of Mississippi in approximately 5000 ft of water. The Deepwater Horizon was considered an ultra-deepwater, dynamically positioned, column-stabilized, semisubmersible mobile offshore drilling unit (MODU) and could operate in waters of up to 8000-ft deep. Semisubmersibles are rigs that have platforms with hulls, columns, or pontoons that have sufficient buoyancy to cause the structure to float, but with weight sufficient enough to keep the structure upright. The Deepwater Horizon housed 126 workers, and its task was to drill wells, extract and process oil and natural gas from the Gulf of Mexico, and export the products to shore. As with any large venture, there are several principle players in an oil exploration and development process. The rig was owned by Transocean, but the principal developer of the Macondo Prospect oil field was British Petroleum Oil Company (BP). The Horizon had been leased to BP on a 3-year contract for deployment in the Gulf of Mexico following its construction. On April 20, 2010, an explosion on the Deepwater Horizon and its subsequent sinking 2 days later resulted in the largest marine oil spill in the history of the United States, which resulted in the death of 11 workers.

On April 20, 2010, at 10:45 PM EST, a sudden explosion rocked the Deepwater Horizon oil platform. The resulting fire traveled so fast that survivors stated they had less than 5 minutes to evacuate the platform after the first fire alarm. The majority of the workers had to evacuate the platform using the lifeboats from an auxiliary ship, the M/V Damon B Bankston, a workboat assigned to the Deepwater Horizon. The Bankston had been hired to service the large platform oil rig. After the evacuation, 11 persons remained unaccounted for, and rescue procedures were put into place.

The US Coast Guard launched a rescue operation. Two cutters, four helicopters, and a rescue plane were involved in the search. The Coast Guard conducted a 3-day search covering approximately 5300 mi. They called off the search for the missing persons, concluding that the “reasonable expectations of survival” had passed. Officials concluded that the missing workers might have been near the area of the blast and may not have been able to escape (7). After many investigations, it has been suggested that the cause of the explosion and resulting fire was a bubble of methane gas that escaped from the well and rose up through the pipes, expanding and blowing out seals and barriers as it rose before exploding on the oil rig.

The Deepwater Horizon had been tethered to the ocean floor by a pipe used to extract oil called a riser. Because of the sinking platform, the pipe was damaged. The damaged pipe began leaking tremendous amount of oil in what is commonly known as a gusher. Huge quantities of crude oil gushed from the riser pipe for approximately 3 months. A device called a blowout preventer (BOP) attached to the pipe at the ocean floor level to prevent such an occurrence failed to operate. Numerous attempts to manually operate the BOP also failed. The rate of oil that was released from the riser soon became a hotly debated issue. Real-time video feeds from the scene were played all over the United States and in fact for the world to see. Eventually, the resulting oil spill would cover almost 30,000 square miles of the ocean, an area, depending on weather conditions, larger than the state of South Carolina. The inaccuracies concerning the amount of oil release from government responders conflicted with the estimates of nongovernment scientists, who suggested that the oil release figures were being underreported. Though, in reality, the exact quantity of oil released was really not the issue. The real issue was how to clean up the oil that was there and, subsequently, preventing future occurrences. According to the most reliable estimate, there was roughly five million barrels of oil released by the Macondo well, with roughly 4.2 million barrels pouring into the waters of the Gulf of Mexico (7).

BP's attempts to plug the leak had become a long and arduous task. BP engineers' initial plan was to use Remotely Operating Underwater Vehicles (ROVs) to stop the leak by remotely activating the BOP. The BOP was “a massive five story, 450 ton stack of shutoff valves, rams, housings, tanks and hydraulic tubing that sits on top of the well” (6, 7). As previously stated, the BOP failed to operate and speculation was that gas hydrates entered and formed in the BOP after a methane bubble rose up through the riser and blew out the seals and barriers in the pipes, causing it to malfunction.

BP's next and subsequent attempts had become exercises in futility. On May 7, BP engineers decided they would use a “top hat” or cofferdam to control the escaping oil from the broken riser. A top hat is a containment dome that is maneuvered over a blowout to collect the escaping oil so that it can be funneled through a pipe up to an awaiting drill ship on the surface. Except this top hat was 98 tons of steel. This project soon floundered because again, “the cofferdam containment system failed, becoming iced up with methane hydrates when hydrocarbons from the end of riser proved to have a higher gas content than anticipated” (6). A second smaller top hat that weighed a mere 2 tons, with the ability to be injected with alcohol to act as an antifreeze to reduce the formation of gas hydrates was the next course of action, but that plan was abandoned on May 12, when engineers became unsure that the plan would work either. “The first significant success at reducing the release of oil came on May 17, 2010 when robots inserted a four-inch diameter Riser Insertion Tube Tool (RITT) into the Horizon's riser, a twenty one-inch diameter pipe between the well and the broken end of the riser on the seafloor in five-thousand feet of water” (7). The RITT is supposed to work like a giant straw that siphons off the leaking oil and transports it to an awaiting tanker on the surface. This attempt brought some success.

The company's long-range plan was to initiate relief wells that would intercept the bored out well at approximately 13,000 ft below the ocean floor. After the relief wells were completed, heavy fluids and cement could be pumped down the damaged hole to kill the well, this is referred to as a top kill. The only problem with this plan is it would take a minimum of 90 days to accomplish. Thus, the reasoning for the stopgaps put into play was to reduce the oil leak at the broken riser early on after the explosion. On May 25, the RITT was disabled for a “top kill” procedure scheduled for the following day. “On May 26, 2010, the U.S. government gave BP the approval to proceed with a ‘top kill’ operation to stop the flow of oil from the damaged well. The procedure was intended to stop the flow of oil and gas from the damaged well and ultimately kill it by injecting heavy drilling fluids through the blowout preventer. On May 29, 2010, BP engineers said that the ‘top kill’ technique had failed. Over thirty thousand barrels of heavy mud was injected into the well in three attempts at rates of up to 80 barrels a minute. Several different bridging materials had been tried and still the operation did not overcome the flow from the well” (7). After 86 days, and several failed attempts and efforts to seal the leak, on July 15, BP succeeded in stopping the flow of oil into the Gulf of Mexico.

Much of the work on oil platforms has become automated in functions below the waves and on the ocean floor. But human error still manifests itself from time to time on these huge sea-going structures. These drilling rigs are some of the largest moveable man-made structures in the world; as such they have become virtual cities afloat that will always have minor equipment failure and human error, not to mention working in hurricane-prone environments. The Deepwater Horizon was no different; it had a long history of spills, fires, and other mishaps before the Gulf oil spill in April 2010. There is even a collision documented in its recent history. “Because vessels like the Deepwater Horizon operate 24 hours a day, Coast Guard officials said minor equipment problems appear frequently. If these problems are not corrected then such incidents could mushroom into bigger concerns” (9). The agency responsible for investigating the safety of offshore and gas operations is the US Department of the Interior's Minerals Management Service (MMS). The MMS had an extensive, detailed inspection program to help ensure the safety of offshore oil and gas operations. MMS inspectors are placed offshore on oil and gas drilling rigs and production platforms to audit operator compliance with extensive safety and environmental protection requirements.

The Deepwater Horizon had experienced many problems before.

• In 2005, the oil rig, still under contract with BP, “spilled 212 barrels of an oil based lubricant due to equipment failure and human error. That spill was probably caused by not screwing the pipe tightly enough and not adequately sealing the well with cement, as well as a possible poor alignment of the rig, according to records maintained by the federal Minerals Management Service” (9). Actions were taken following that spill. The MMS inspectors recommended increasing the amount of cement used during this process and applying more torque when screwing in its pipes.
• Also in 2005, a crane operator sparked a hazardous fire onboard Deep Horizon while refueling. His inattention caused diesel to overflow, and a spark initiated a fire on board. “In June 2003, the rig floated off course in high seas, resulting in the release of 944 barrels of oil. MMS blamed bad weather and poor judgment by the captain.”
• “A month later, equipment failure and high currents led to the loss of an additional 74 barrels of oil” (9). These were just a few of the mishaps that were reported, and investigated by the MMS on the Deepwater Horizon before the blowout on April 2010.

The MMS, the caretaker of America's federal lands and oceans, and watchdog of the oil and gas drilling industry had come under increasing criticism in the years before the Deepwater Horizon mishap. “Investigators from the Interior Department's inspector general's office said more than a dozen employees, including the former director of the oil royalty-in-kind program, took meals, ski trips, sports tickets and golf outings from industry representatives. The report alleges that the former director, Gregory W. Smith, also netted more than $30,000 from improper outside work” (10). Government officials were also alleged to have taken bribes so that they would direct the contracts to favored clients. In the report, investigators said they “discovered a culture of substance abuse and promiscuity” in which employees accepted gratuities “with prodigious frequency” (10).

The responsibility for the initial cleanup was assumed by BP Oil Corporation. Tony Haywood, Chief Executive Officer (CEO), formally verbalized to the American people that his company was taking full responsibility for the disaster, “and where people can present legitimate claims for damages we will honor them.” To augment the cost of the cleanup, under the Federal Water Pollution Control Act, The Oil Spill Liability Trust Fund (OSLTF), established in the Treasury helped defer expenses of a federal response to oil pollution and to help compensate claims for oil removal and damages as authorized by the Oil Pollution Act (OPA) of 1990. “The OPA requires that responsible parties pay the entire price tag for cleaning up after spills from offshore drilling, including lost profits, destroyed property and lost tax revenue, but the statute caps their liability for economic damages at $75 million. Aggressive collection efforts are consistent with the ‘polluter pays’ public policy underlying the OPA. BP and Transocean have been named as responsible parties, although all claims are still being processed centrally through the BP Corporation” (7).

Many events led to the explosion on the Deepwater Horizon platform. Numerous events took place that contributed to the disaster. Working at great depths, 5000 ft or more, and pressures >2000 lb/in² (13,789,514.56 Pa) should be reevaluated. Problems at these depths have very real dangers and are unfamiliar. Most equipments used to secure a well run amok have only been tested at depths half that of the Deepwater Horizon's. Guy Cantwell, a spokesman for the oil rig's owner Transocean Ltd, said that the Swiss-based company planned to conduct its own investigation of what caused the explosion aboard the Deepwater Horizon. “The industry is going to learn a lot from this. That's what happens in these kinds of disasters” he said, citing a 1988 explosion of the Piper Alpha rig in the North Sea and a 1979 blowout of Mexico's IXTOC I in the eastern Gulf (9). After the North Sea incident in which 167 men were killed, Great Britain revamped its safety requirements concerning deep water drilling. There is no doubt that the same will happen in the United States. Numerous “well topping” devices and associated installation accessories have already been designed, built, and readied for future deployment, particularly where gas hydrates are concerned. It seems as though deep water drilling is here to stay.

At the time of writing of this book, we are only 1 year since this event occurred. There is still much controversy as to the long-term effects of the spill. Only time will tell what the long-term ecological effects of the spill are.