A blowout is the uncontrolled release of crude oil and/or natural gas from an oil well or gas well after pressure control systems have failed. [1] Modern wells have blowout preventers intended to prevent such an occurrence. An accidental spark during a blowout can lead to a catastrophic oil or gas fire.
Prior to the advent of pressure control equipment in the 1920s, the uncontrolled release of oil and gas from a well while drilling was common and was known as an oil gusher, gusher or wild well.
Gushers were an icon of oil exploration during the late 19th and early 20th centuries. During that era, the simple drilling techniques, such as cable-tool drilling, and the lack of blowout preventers meant that drillers could not control high-pressure reservoirs. When these high-pressure zones were breached, the oil or natural gas would travel up the well at a high rate, forcing out the drill string and creating a gusher. A well which began as a gusher was said to have "blown in": for instance, the Lakeview Gusher blew in in 1910. These uncapped wells could produce large amounts of oil, often shooting 200 feet (61 m) or higher into the air. [2] A blowout primarily composed of natural gas was known as a gas gusher.
Despite being symbols of new-found wealth, gushers were dangerous and wasteful. They killed workmen involved in drilling, destroyed equipment, and coated the landscape with thousands of barrels of oil; additionally, the explosive concussion released by the well when it pierces an oil/gas reservoir has been responsible for a number of oilmen losing their hearing entirely; standing too near to the drilling rig at the moment it drills into the oil reservoir is extremely hazardous. The impact on wildlife is very hard to quantify, but can only be estimated to be mild in the most optimistic models—realistically, the ecological impact is estimated by scientists across the ideological spectrum to be severe, profound, and lasting. [3]
To complicate matters further, the free flowing oil was—and is—in danger of igniting. [4] One dramatic account of a blowout and fire reads,
With a roar like a hundred express trains racing across the countryside, the well blew out, spewing oil in all directions. The derrick simply evaporated. Casings wilted like lettuce out of water, as heavy machinery writhed and twisted into grotesque shapes in the blazing inferno. [5]
The development of rotary drilling techniques where the density of the drilling fluid is sufficient to overcome the downhole pressure[ definition needed ] of a newly penetrated zone meant that gushers became avoidable. However, if the fluid density was not adequate or fluids were lost to the formation, then there was still a significant risk of a well blowout.
In 1924 the first successful blowout preventer was brought to market. [6] The BOP valve affixed to the wellhead could be closed in the event of drilling into a high pressure zone, and the well fluids contained. Well control techniques could be used to regain control of the well. As the technology developed, blowout preventers became standard equipment, and gushers became a thing of the past.
In the modern petroleum industry, uncontrollable wells became known as blowouts and are comparatively rare. There has been significant improvement in technology, well control techniques, and personnel training which has helped to prevent their occurring. [1] From 1976 to 1981, 21 blowout reports are available. [1]
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights, and other organic compounds, found in geologic formations beneath the Earth's surface. Because most hydrocarbons are lighter than rock or water, they often migrate upward and occasionally laterally through adjacent rock layers until either reaching the surface or becoming trapped within porous rocks (known as reservoirs) by impermeable rocks above. When hydrocarbons are concentrated in a trap, an oil field forms, from which the liquid can be extracted by drilling and pumping. The downhole pressure[ definition needed ] in the rock structures changes depending upon the depth and the characteristics of the source rock. Natural gas (mostly methane) may be present also, usually above the oil within the reservoir, but sometimes dissolved in the oil at reservoir pressure and temperature. Dissolved gas typically comes out of solution as free gas as the pressure is reduced either under controlled production operations or in a kick, or in an uncontrolled blowout. The hydrocarbon in some reservoirs may be essentially all natural gas.
The downhole fluid pressures are controlled in modern wells through the balancing of the hydrostatic pressure provided by the mud column. Should the balance of the drilling mud pressure be incorrect (i.e., the mud pressure gradient is less than the formation pore pressure gradient), then formation fluids (oil, natural gas, and/or water) can begin to flow into the wellbore and up the annulus (the space between the outside of the drill string and the wall of the open hole or the inside of the casing), and/or inside the drill pipe. This is commonly called a kick. Ideally, mechanical barriers such as blowout preventers (BOPs) can be closed to isolate the well while the hydrostatic balance is regained through circulation of fluids in the well. But if the well is not shut in (common term for the closing of the blow-out preventer), a kick can quickly escalate into a blowout when the formation fluids reach the surface, especially when the influx contains gas that expands rapidly with the reduced pressure as it flows up the wellbore, further decreasing the effective weight of the fluid.
Early warning signs of an impending well kick while drilling are:
Other warning signs during the drilling operation are:
The primary means of detecting a kick while drilling is a relative change in the circulation rate back up to the surface into the mud pits. The drilling crew or mud engineer keeps track of the level in the mud pits and closely monitors the rate of mud returns versus the rate that is being pumped down the drill pipe. Upon encountering a zone of higher pressure than is being exerted by the hydrostatic head of the drilling mud (including the small additional frictional head while circulating) at the bit, an increase in mud return rate would be noticed as the formation fluid influx blends in with the circulating drilling mud. Conversely, if the rate of returns is slower than expected, it means that a certain amount of the mud is being lost to a thief zone somewhere below the last casing shoe. This does not necessarily result in a kick (and may never become one); however, a drop in the mud level might allow influx of formation fluids from other zones if the hydrostatic head is reduced to less than that of a full column of mud.[ citation needed ]
The first response to detecting a kick would be to isolate the wellbore from the surface by activating the blow-out preventers and closing in the well. Then the drilling crew would attempt to circulate in a heavier kill fluid to increase the hydrostatic pressure (sometimes with the assistance of a well control company). In the process, the influx fluids will be slowly circulated out in a controlled manner, taking care not to allow any gas to accelerate up the wellbore too quickly by controlling casing pressure with chokes on a predetermined schedule.
This effect will be minor if the influx fluid is mainly salt water. And with an oil-based drilling fluid it can be masked in the early stages of controlling a kick because gas influx may dissolve into the oil under pressure at depth, only to come out of solution and expand rather rapidly as the influx nears the surface. Once all the contaminant has been circulated out, the shut-in casing pressure should have reached zero.[ citation needed ]
Capping stacks are used for controlling blowouts. The cap is an open valve that is closed after bolted on. [23]
Well blowouts can occur during the drilling phase, during well testing, during well completion, during production, or during workover activities. [1]
Blowouts can eject the drill string out of the well, and the force of the escaping fluid can be strong enough to damage the drilling rig. In addition to oil, the output of a well blowout might include natural gas, water, drilling fluid, mud, sand, rocks, and other substances.
Blowouts will often be ignited from sparks from rocks being ejected, or simply from heat generated by friction. A well control company then will need to extinguish the well fire or cap the well, and replace the casing head and other surface equipment. If the flowing gas contains poisonous hydrogen sulfide, the oil operator might decide to ignite the stream to convert this to less hazardous substances.[ citation needed ]
Sometimes blowouts can be so forceful that they cannot be directly brought under control from the surface, particularly if there is so much energy in the flowing zone that it does not deplete significantly over time. In such cases, other wells (called relief wells) may be drilled to intersect the well or pocket, in order to allow kill-weight fluids to be introduced at depth. When first drilled in the 1930s relief wells were drilled to inject water into the main drill well hole. [24] Contrary to what might be inferred from the term, such wells generally are not used to help relieve pressure using multiple outlets from the blowout zone.
The two main causes of a subsea blowout are equipment failures and imbalances with encountered subsurface reservoir pressure. [25] Subsea wells have pressure control equipment located on the seabed or between the riser pipe and drilling platform. Blowout preventers (BOPs) are the primary safety devices designed to maintain control of geologically driven well pressures. They contain hydraulic-powered cut-off mechanisms to stop the flow of hydrocarbons in the event of a loss of well control. [26]
Even with blowout prevention equipment and processes in place, operators must be prepared to respond to a blowout should one occur. Before drilling a well, a detailed well construction design plan, an Oil Spill Response Plan as well as a Well Containment Plan must be submitted, reviewed and approved by BSEE and is contingent upon access to adequate well containment resources in accordance to NTL 2010-N10. [27]
The Deepwater Horizon well blowout in the Gulf of Mexico in April 2010 occurred at a 5,000 feet (1,500 m) water depth. [28] Current blowout response capabilities in the U.S. Gulf of Mexico meet capture and process rates of 130,000 barrels of fluid per day and a gas handling capacity of 220 million cubic feet per day at depths through 10,000 feet. [29]
An underground blowout is a special situation where fluids from high pressure zones flow uncontrolled to lower pressure zones within the wellbore. Usually this is from deeper higher pressure zones to shallower lower pressure formations. There may be no escaping fluid flow at the wellhead. However, the formation(s) receiving the influx can become overpressured, a possibility that future drilling plans in the vicinity must consider.[ citation needed ]
Myron M. Kinley was a pioneer in fighting oil well fires and blowouts. He developed many patents and designs for the tools and techniques of oil firefighting. His father, Karl T. Kinley, attempted to extinguish an oil well fire with the help of a massive explosion—a method still in common use for fighting oil fires. Myron and Karl Kinley first successfully used explosives to extinguish an oil well fire in 1913. [30] Kinley would later form the M. M. Kinley Company in 1923. [30] Asger "Boots" Hansen and Edward Owen "Coots" Matthews also begin their careers under Kinley.
Paul N. "Red" Adair joined the M. M. Kinley Company in 1946, and worked 14 years with Myron Kinley before starting his own company, Red Adair Co., Inc., in 1959.
Red Adair Co. has helped in controlling offshore blowouts, including:
The 1968 American film Hellfighters , which starred John Wayne, is about a group of oil well firefighters, based loosely on Adair's life; Adair, Hansen, and Matthews served as technical advisors on the film.
In 1994, Adair retired and sold his company to Global Industries. Management of Adair's company left and created International Well Control (IWC). In 1997, they would buy the company Boots & Coots International Well Control, Inc., which was founded by Hansen and Matthews in 1978.
After the Macondo-1 blowout on the Deepwater Horizon, the offshore industry collaborated with government regulators to develop a framework to respond to future subsea incidents. As a result, all energy companies operating in the deep-water U.S. Gulf of Mexico must submit an OPA 90 required Oil Spill Response Plan with the addition of a Regional Containment Demonstration Plan prior to any drilling activity. [32] In the event of a subsea blowout, these plans are immediately activated, drawing on some of the equipment and processes effectively used to contain the Deepwater Horizon well as others that have been developed in its aftermath.
In order to regain control of a subsea well, the Responsible Party would first secure the safety of all personnel on board the rig and then begin a detailed evaluation of the incident site. Remotely operated underwater vehicles (ROVs) would be dispatched to inspect the condition of the wellhead, blowout preventer (BOP) and other subsea well equipment. The debris removal process would begin immediately to provide clear access for a capping stack.
Once lowered and latched on the wellhead, a capping stack uses stored hydraulic pressure to close a hydraulic ram and stop the flow of hydrocarbons. [33] If shutting in the well could introduce unstable geological conditions in the wellbore, a cap and flow procedure would be used to contain hydrocarbons and safely transport them to a surface vessel. [34]
The Responsible Party works in collaboration with BSEE and the United States Coast Guard to oversee response efforts, including source control, recovering discharged oil and mitigating environmental impact. [35]
Several not-for-profit organizations provide a solution to effectively contain a subsea blowout. HWCG LLC and Marine Well Containment Company operate within the U.S. Gulf of Mexico [36] waters, while cooperatives like Oil Spill Response Limited offer support for international operations.
On Sep. 30, 1966, the Soviet Union experienced blowouts on five natural gas wells in Urta-Bulak, an area about 80 kilometers from Bukhara, Uzbekistan. It was claimed in Komsomoloskaya Pravda that after years of burning uncontrollably they were able to stop them entirely. [37] The Soviets lowered a specially made 30 kiloton nuclear physics package into a 6-kilometre (20,000 ft) borehole drilled 25 to 50 metres (82 to 164 ft) away from the original (rapidly leaking) well. A nuclear explosive was deemed necessary because conventional explosives both lacked the necessary power and would also require a great deal more space underground. When the device was detonated, it crushed the original pipe that was carrying the gas from the deep reservoir to the surface and vitrified the surrounding rock. This caused the leak and fire at the surface to cease within approximately one minute of the explosion, and proved to be a permanent solution. An attempt on a similar well was not as successful. Other tests were for such experiments as oil extraction enhancement (Stavropol, 1969) and the creation of gas storage reservoirs (Orenburg, 1970). [38]
Data from industry information. [1] [39]
Year | Rig Name | Rig Owner | Type | Damage / details |
---|---|---|---|---|
1955 | S-44 | Chevron Corporation | Sub Recessed pontoons | Blowout and fire. Returned to service. |
1959 | C. T. Thornton | Reading & Bates | Jackup | Blowout and fire damage. |
1964 | C. P. Baker | Reading & Bates | Drill barge | Blowout in Gulf of Mexico, vessel capsized, 22 killed. |
1965 | Trion | Royal Dutch Shell | Jackup | Destroyed by blowout. |
1965 | Paguro | SNAM | Jackup | Destroyed by blowout and fire. |
1968 | Little Bob | Coral | Jackup | Blowout and fire, killed 7. |
1969 | Wodeco III | Floor drilling | Drilling barge | Blowout |
1969 | Sedco 135G | Sedco Inc | Semi-submersible | Blowout damage |
1969 | Rimrick Tidelands | ODECO | Submersible | Blowout in Gulf of Mexico |
1970 | Stormdrill III | Storm Drilling | Jackup | Blowout and fire damage. |
1970 | Discoverer III | Offshore Co. | Drillship | Blowout (S. China Seas) |
1971 | Big John | Atwood Oceanics | Drill barge | Blowout and fire. |
1971 | Wodeco II | Floor Drilling | Drill barge | Blowout and fire off Peru, 7 killed.[ citation needed ] |
1972 | J. Storm II | Marine Drilling Co. | Jackup | Blowout in Gulf of Mexico |
1972 | M. G. Hulme | Reading & Bates | Jackup | Blowout and capsize in Java Sea. |
1972 | Rig 20 | Transworld Drilling | Jackup | Blowout in Gulf of Martaban. |
1973 | Mariner I | Santa Fe Drilling | Semi-sub | Blowout off Trinidad, 3 killed. |
1975 | Mariner II | Santa Fe Drilling | Semi-submersible | Lost BOP during blowout. |
1975 | J. Storm II | Marine Drilling Co. | Jackup | Blowout in Gulf of Mexico.[ citation needed ] |
1976 | Petrobras III | Petrobras | Jackup | No info. |
1976 | W. D. Kent | Reading & Bates | Jackup | Damage while drilling relief well.[ citation needed ] |
1977 | Maersk Explorer | Maersk Drilling | Jackup | Blowout and fire in North Sea[ citation needed ] |
1977 | Ekofisk Bravo | Phillips Petroleum | Platform | Blowout during well workover. [40] |
1978 | Scan Bay | Scan Drilling | Jackup | Blowout and fire in the Persion Gulf.[ citation needed ] |
1979 | Salenergy II | Salen Offshore | Jackup | Blowout in Gulf of Mexico |
1979 | Sedco 135 | Sedco Drilling | Semi-submersible | Blowout and fire in Bay of Campeche Ixtoc I well. [41] |
1980 | Sedco 135C | Sedco Drilling | Semi-submersible | Blowout and fire of Nigeria. |
1980 | Discoverer 534 | Offshore Co. | Drillship | Gas escape caught fire.[ citation needed ] |
1980 | Ron Tappmeyer | Reading & Bates | Jackup | Blowout in Persian Gulf, 5 killed.[ citation needed ] |
1980 | Nanhai II | People's Republic of China | Jackup | Blowout of Hainan Island.[ citation needed ] |
1980 | Maersk Endurer | Maersk Drilling | Jackup | Blowout in Red Sea, 2 killed.[ citation needed ] |
1980 | Ocean King | ODECO | Jackup | Blowout and fire in Gulf of Mexico, 5 killed. [42] |
1980 | Marlin 14 | Marlin Drilling | Jackup | Blowout in Gulf of Mexico[ citation needed ] |
1981 | Penrod 50 | Penrod Drilling | Submersible | Blowout and fire in Gulf of Mexico.[ citation needed ] |
1984 | Plataforma Central de Enchova | Petrobras | fixed platform | Blowout and fire in Campos Basin, Rio de Janeiro, Brazil, 37 fatalities. |
1985 | West Vanguard | Smedvig | Semi-submersible | Shallow gas blowout and fire in Norwegian sea, 1 fatality. |
1981 | Petromar V | Petromar | Drillship | Gas blowout and capsize in S. China seas.[ citation needed ] |
1983 | Bull Run | Atwood Oceanics | Tender | Oil and gas blowout Dubai, 3 fatalities. |
1988 | Ocean Odyssey | Diamond Offshore Drilling | Semi-submersible | Gas blowout at BOP and fire in the UK North Sea, 1 killed. |
1988 | Plataforma Central de Enchova | Petrobras | fixed platform | Blowout and fire in Campos Basin, Rio de Janeiro, Brazil, no fatality, platform entirely destroyed. |
1989 | Al Baz | Santa Fe | Jackup | Shallow gas blowout and fire in Nigeria, 5 killed. [43] |
1993 | M. Naqib Khalid | Naqib Co. | Naqib Drilling | fire and explosion. Returned to service. |
1993 | Actinia | Transocean | Semi-submersible | Sub-sea blowout in Vietnam. [44] |
2001 | Ensco 51 | Ensco | Jackup | Gas blowout and fire, Gulf of Mexico, no casualties [45] |
2002 | Arabdrill 19 | Arabian Drilling Co. | Jackup | Structural collapse, blowout, fire and sinking. [46] |
2004 | Adriatic IV | Global Santa Fe | Jackup | Blowout and fire at Temsah platform, Mediterranean Sea [47] |
2007 | Usumacinta | PEMEX | Jackup | Storm forced rig to move, causing well blowout on Kab 101 platform, 22 killed. [48] |
2009 | West Atlas / Montara | Seadrill | Jackup / Platform | Blowout and fire on rig and platform in Australia. [49] |
2010 | Deepwater Horizon | Transocean | Semi-submersible | Blowout and fire on the rig, subsea well blowout, killed 11 in explosion. |
2010 | Vermilion Block 380 | Mariner Energy | Platform | Blowout and fire, 13 survivors, 1 injured. [50] [51] |
2012 | KS Endeavour | KS Energy Services | Jack-Up | Blowout and fire on the rig, collapsed, killed 2 in explosion. |
2012 | Elgin platform | Total | Platform | Blowout and prolonged sour gas release, no injuries. |
An oil well is a drillhole boring in Earth that is designed to bring petroleum oil hydrocarbons to the surface. Usually some natural gas is released as associated petroleum gas along with the oil. A well that is designed to produce only gas may be termed a gas well. Wells are created by drilling down into an oil or gas reserve and if necessary equipped with extraction devices such as pumpjacks. Creating the wells can be an expensive process, costing at least hundreds of thousands of dollars, and costing much more when in difficult-to-access locations, e.g., offshore. The process of modern drilling for wells first started in the 19th century but was made more efficient with advances to oil drilling rigs and technology during the 20th century.
Directional drilling is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring, and surface in seam (SIS), which horizontally intersects a vertical bore target to extract coal bed methane.
The Atlantis oil field is the third largest oil field in the Gulf of Mexico. The field was discovered in 1998 and is located at the Green Canyon blocks 699, 700, 742, 743, and 744 in United States federal waters in the Gulf of Mexico about 130 miles (210 km) from the coast of Louisiana. The oil field lies in water depths ranging from 4,400 to 7,100 feet. The subsea structure of Atlantis has long been the target of safety critics.
Ixtoc 1 was an exploratory oil well being drilled by the semi-submersible drilling rig Sedco 135 in the Bay of Campeche of the Gulf of Mexico, about 100 km (62 mi) northwest of Ciudad del Carmen, Campeche in waters 50 m (164 ft) deep. On 3 June 1979, the well suffered a blowout resulting in the largest oil spill in history at its time. To-date, it remains the second largest oil spill in history after the Deepwater Horizon oil spill.
Well control is the technique used in oil and gas operations such as drilling, well workover and well completion for maintaining the hydrostatic pressure and formation pressure to prevent the influx of formation fluids into the wellbore. This technique involves the estimation of formation fluid pressures, the strength of the subsurface formations and the use of casing and mud density to offset those pressures in a predictable fashion. Understanding pressure and pressure relationships is important in well control.
In geotechnical engineering, drilling fluid, also known as drilling mud, is used to aid the drilling of boreholes into the earth. Used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are also used for much simpler boreholes, such as water wells.
A blowout preventer (BOP) is a specialized valve or similar mechanical device, used to seal, control and monitor oil and gas wells to prevent blowouts, the uncontrolled release of crude oil or natural gas from a well. They are usually installed in stacks of other valves.
The Lakeview Gusher was an eruption of hydrocarbons from a pressurized oil well in the Midway-Sunset Oil Field in Kern County, California, in 1910. Caused by a blowout, it created the largest accidental oil spill in history, lasting 18 months and releasing an estimated 9 million barrels of crude oil.
Offshore drilling is a mechanical process where a wellbore is drilled below the seabed. It is typically carried out in order to explore for and subsequently extract petroleum that lies in rock formations beneath the seabed. Most commonly, the term is used to describe drilling activities on the continental shelf, though the term can also be applied to drilling in lakes, inshore waters and inland seas.
The Santa Barbara oil spill occurred in January and February 1969 in the Santa Barbara Channel, near the city of Santa Barbara in Southern California. It was the largest oil spill in United States waters at the time. It remains the largest oil spill to have occurred in the waters off California.
Oilfield terminology refers to the jargon used by those working in fields within and related to the upstream segment of the petroleum industry. It includes words and phrases describing professions, equipment, and procedures specific to the industry. It may also include slang terms used by oilfield workers to describe the same.
The Macondo Prospect is an oil and gas prospect in the United States Exclusive Economic Zone of the Gulf of Mexico, off the coast of Louisiana. The prospect was the site of the Deepwater Horizon drilling rig explosion in April 2010 that led to a major oil spill in the region from the first exploration well, named itself MC252-1, which had been designed to investigate the existence of the prospect.
On April 20, 2010, an explosion and fire occurred on the Deepwater Horizon semi-submersible mobile offshore drilling unit, which was owned and operated by Transocean and drilling for BP in the Macondo Prospect oil field about 40 miles (64 km) southeast off the Louisiana coast. The explosion and subsequent fire resulted in the sinking of the Deepwater Horizon and the deaths of 11 workers; 17 others were injured. The same blowout that caused the explosion also caused an oil well fire and a massive offshore oil spill in the Gulf of Mexico, considered the largest accidental marine oil spill in the world, and the largest environmental disaster in United States history.
The Cameron ram-type blowout preventer was the first successful blowout preventer (BOP) for oil wells. It was developed by James S. Abercrombie and Harry S. Cameron in 1922. The device was issued U.S. patent 1,569,247 on January 12, 1926. The blowout preventer was designated as a Mechanical Engineering Landmark in 2003.
The following is a timeline of the Deepwater Horizon oil spill. It was a massive oil spill in the Gulf of Mexico, the largest offshore spill in U.S. history. It was a result of the well blowout that began with the Deepwater Horizon drilling rig explosion on April 20, 2010.
Offshore oil spill prevention and response is the study and practice of reducing the number of offshore incidents that release oil or hazardous substances into the environment and limiting the amount released during those incidents.
Following is a timeline of the Deepwater Horizon oil spill for July 2010.
Efforts to stem the Deepwater Horizon oil spill were ongoing from the time that the Deepwater Horizon exploded on April 20, 2010 until the well was sealed by a cap on July 15, 2010. Various species of dolphins and other mammals, birds, and the endangered sea turtles have been killed either directly or indirectly by the oil spill. The Deepwater Horizon spill has surpassed in volume the 1989 Exxon Valdez oil spill as the largest ever to originate in U.S.-controlled waters; it is comparable to the 1979 Ixtoc I oil spill in total volume released.
Oil well control is the management of the dangerous effects caused by the unexpected release of formation fluid, such as natural gas and/or crude oil, upon surface equipment of oil or gas drilling rigs and escaping into the atmosphere. Technically, oil well control involves preventing the formation gas or fluid (hydrocarbons), usually referred to as kick, from entering into the wellbore during drilling or well interventions.
The Deepwater Horizon investigation included several investigations and commissions, among others reports by National Incident Commander Thad Allen, United States Coast Guard, National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling, Bureau of Ocean Energy Management, Regulation and Enforcement, National Academy of Engineering, National Research Council, Government Accountability Office, National Oil Spill Commission, and Chemical Safety and Hazard Investigation Board.
One of the greatest obstacles they met with when boring was the striking a strong vein of oil, a spontaneous outburst, which shot up high as the tops of the highest trees!