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Uncontrolled release of crude oil and/or natural gas from a well

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The Lucas Gusher at Spindletop, Texas ()

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 s, 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.

History

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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 . 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 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 to , 21 blowout reports are available.[1]

Notable gushers

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Causes

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Reservoir pressure

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A petroleum trap. An irregularity (the trap) in a layer of impermeable rocks (the seal) retains upward-flowing petroleum, forming a reservoir.

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.

Formation kick

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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:

• Sudden change in drilling rate;
• Reduction in drillpipe weight;
• Change in pump pressure;
• Change in drilling fluid return rate.

Other warning signs during the drilling operation are:

• Returning mud "cut" by (i.e., contaminated by) gas, oil or water;
• Connection gases, high background gas units, and high bottoms-up gas units detected in the mudlogging unit.

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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]

Well control

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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]

Types

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Ixtoc I oil well blowout

Well blowouts can occur during the drilling phase, during well testing, during well completion, during production, or during workover activities.[1]

Surface blowouts

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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 s 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.

Subsea blowouts

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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 -N10.[27]

The Deepwater Horizon well blowout in the Gulf of Mexico in April 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]

Underground blowouts

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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]

Blowout control companies

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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 .[30] Kinley would later form the M. M. Kinley Company in .[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 , and worked 14 years with Myron Kinley before starting his own company, Red Adair Co., Inc., in .

Red Adair Co. has helped in controlling offshore blowouts, including:

The 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 , Adair retired and sold his company to Global Industries. Management of Adair's company left and created International Well Control (IWC). In , they would buy the company Boots & Coots International Well Control, Inc., which was founded by Hansen and Matthews in .

Methods of quenching

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Subsea well containment

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If you are looking for more details, kindly visit Subsea Blowout Preventer Manufacturer.

Government Accountability Office diagram showing subsea well containment operations

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.

Use of nuclear explosions

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On Sep. 30, , 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, ) and the creation of gas storage reservoirs (Orenburg, ).[38]

Notable offshore well blowouts

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Data from industry information.[1][39]

See also

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References

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In oil well drilling, safety is crucial, and one key piece of equipment that ensures this is the blowout preventer (BOP). This article will cover the main parts of a BOP, their roles, and how they work together to prevent blowouts.

A blowout preventer is a sophisticated device that seals the wellhead and manages oil and gas flow during drilling. It includes several important parts like the annular preventer, rams, and control systems.

Functions and Importance of Blowout Preventers

BOPs are essential in the oil and gas industry to prevent blowouts, or uncontrolled releases of oil and gas. They are designed to seal the wellhead and manage the flow during drilling and intervention activities. Understanding their key components and how they function helps the industry reduce the risk of blowouts.

1. Seal the Wellhead

BOPs create a secure seal around the wellhead to prevent the uncontrolled escape of oil and gas, maintaining well control.

2. Control Well Pressure

Blowout preventers help regulate pressure within the well during drilling, preventing excessive buildup that could lead to a blowout.

3. Facilitate Well Intervention

BOPs enable safe well-intervention activities like wireline operations, tubing or casing replacement, and maintenance, providing a secure environment for technicians.

Blowout preventers are crucial as the last line of defense against blowouts, ensuring the safety of personnel and the environment.

Types of Blowout Preventers: Annular BOPs and Ram BOPs

Blowout preventers are essential tools in the oil and gas industry, designed for specific functions. The two primary types are annular BOPs and ram BOPs.

Annular BOPs

Annular blowout preventers are rubber, doughnut-shaped devices that encircle the drill pipe and create a seal when closed. They feature a packer element that expands and contracts to ensure a secure seal, offering flexibility and pressure control across various pipe sizes.

Ram BOPs

Ram blowout preventers use mechanical rams, activated by hydraulic systems, to close around the drill pipe or seal the wellbore. They include Blind Rams, Pipe Rams, and Shear Rams.

Blind Rams

Blind rams, also known as blind shear rams, are solid rams with no openings. They are used to fully seal the wellbore during emergencies by stopping uncontrolled flow.

Pipe Rams

Pipe rams feature an opening for the drill pipe and create a secure seal by closing around it when activated. This helps keep the flow of oil and drilling fluids flowing properly.

Shear Rams

Shear rams are equipped with blades to cut and seal the drill pipe during a blowout, preventing uncontrolled releases of oil and gas.

Blowout Preventer Components: Casing Head, Housing, Bonnet, and Stack

A blowout preventer is made up of several crucial parts that work together to ensure its effectiveness. These include the casing head, housing, bonnet, and stack.

Casing Head

The casing head is the lowest part of the blowout preventer assembly. It serves as the foundation, supporting the weight of the BOP stack. It also houses the annular preventer and connects to the well casing.

Housing

The housing is the main body of the blowout preventer, containing the rams and other stack components. It is typically constructed from heavy-duty steel to withstand high pressures and tough conditions like drilling mud.

Bonnet

The bonnet is the upper section of the blowout preventer housing. It provides access to internal components and serves as a mounting point for the control system. Designed for easy removal, it facilitates maintenance and inspections.

Stack

The stack consists of the arrangement of rams and components within the BOP housing. It includes the annular preventer, pipe rams, blind rams, shear rams, and other necessary elements. The stack offers multiple layers of protection against blowouts, with each component serving a specific role.

Understanding the Control System of a Blowout Preventer

The control system of a blowout preventer manages the operation of its components, ensuring proper functionality. It includes hydraulic control panels, accumulators, control valves, and instruments that move the rams and activate the annular preventer.

Located at the surface and operated by trained personnel, the system allows for remote control of the BOP, enhancing safety by keeping workers away from the wellhead during drilling.

The control system provides precise management of the BOP&#;s functions, enabling rapid response in emergencies. Regular testing and maintenance are crucial for its reliability and effectiveness.

Maintenance and Inspection of a Blowout Preventer

Aftermarket services are an essential part of keeping BOPs functioning. Regular maintenance and inspection help ensure effective operations and safe use. This involves routine checks, testing, and preventive measures. Key tasks include:

Visual Inspections

Conduct regular visual checks for damage, corrosion, or wear. Inspect rams, seals, hydraulic hoses, and other components for any visible issues.

Pressure Testing

Perform routine pressure tests to ensure the BOP can handle high pressures. This involves pressurizing the system and checking for leaks or failures.

Preventive Maintenance

Regularly replace worn or damaged parts, lubricate moving components, and perform other preventive tasks to maintain the BOP&#;s reliability.

Documentation and Record-Keeping

 Keep detailed records of all maintenance and inspections. This documentation helps track the BOP&#;s history and ensures compliance with regulatory standards.

Understanding BOP Components and Capabilities with BOP Products

At BOP Products, we manufacture, repair, and service oilfield equipment. These include blowout preventers, ram blocks, and blowout preventer replacement parts. Our commitment to quality and precision ensures that every component we produce meets the highest industry standards. Whether you need new equipment, urgent repairs, or replacement parts, we are your trusted partner in maintaining safe and effective operations.

Contact BOP Products today to learn how our specialized services can keep your equipment performing at its best!

The company is the world’s best BOP Control System supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.