A test that measures the reservoir pressure of the well, obtained at a specific depth or at the midpoint of the producing zone.
A flowing bottomhole pressure test measures pressure while the well continues to flow; a shut-in bottomhole pressure test measures pressure after the well has been shut in for a specified period of time.
See bottomhole pressure, bottomhole pressure gauge.
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For ships, water taken onboard into specific tanks to permit proper angle of repose of the vessel in the water, and to assure structural stability.
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For mobile offshore drilling rigs, weight added to make the rig more seaworthy, increase its draft, or sink it to the seafloor.
Seawater is usually used for ballast, but sometimes concrete or iron is used additionally to lower the rig’s center of gravity permanently.
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A downhole tool, composed primarily of slips, a plug mandrel, and a rubber sealing element, that is run and set in casing to isolate a lower zone while an upper section is being tested or cemented.
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A downhole tool that is located and set to isolate the lower part of the wellbore.
Bridge plugs may be permanent or retrievable, enabling the lower wellbore to be permanently sealed from production or temporarily isolated from a treatment conducted on an upper zone.
A well using a pumping unit and rods to lift fluid.
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One of several valves installed at the wellhead to prevent the escape of pressure either in the annular space between the casing and drill pipe or in open hole (i.e., hole with no drill pipe) during drilling completion operations.
Blowout preventers on land rigs are located beneath the rig at the land’s surface; on jackup or platform rigs, at the water’s surface; and on floating offshore rigs, on the seafloor.
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A large valve at the top of a well that may be closed if the drilling crew loses control of formation fluids.
By closing this valve (usually operated remotely via hydraulic actuators), the drilling crew usually regains control of the reservoir, and procedures can then be initiated to increase the mud density until it is possible to open the bop and retain pressure control of the formation.
Bops come in a variety of styles, sizes and pressure ratings.
Some can effectively close over an open wellbore, some are designed to seal around tubular components in the well (drillpipe, casing or tubing) and others are fitted with hardened steel shearing surfaces that can actually cut through drillpipe.
Since bops are critically important to the safety of the crew, the rig and the wellbore itself, bops are inspected, tested and refurbished at regular intervals determined by a combination of risk assessment, local practice, well type and legal requirements.
Bop tests vary from daily function testing on critical wells to monthly or less frequent testing on wells thought to have low probability of well control problems.
A device made up in the drill stem above the mill to collect bits of junk ground away during a milling operation.
During milling, drilling mud under high pressure forces bits of junk up the narrow space between the boot sub and the hole wall.
When the junk reaches the wider annulus above the boot sub and pressure drops slightly, the junk falls into the boot sub.
A boot sub also can be run above the bit during routine drilling to collect small pieces of junk that may damage the bit or interfere with its operation.
A heavy wall sub placed opposite flowing perforations.
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A curved steel rod on top of the swivel that resembles the handle, or bail, of an ordinary bucket, but is much larger.
Just as an ordinary bucket is hung from a hook by its bail, the swivel is hung from the traveling block’s hook by its bail.
Sometimes, the two steel rods (the links) that attach the elevator to the hook are also called bails.
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To recover bottomhole fluids, samples, mud, sand, or drill cuttings by lowering a cylindrical vessel called a bailer to the bottom of a well, filling it, and retrieving it.
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A pipe connection around a valve or other control mechanism that is installed to permit passage of fluid through the line while adjustments or repairs are being made on the control.
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A delivery of gas to a customer by means of a pipeline other than that customer’s traditional supplier.
For example, delivery of gas to an end user directly off a transmission pipeline without moving the gas through the end user’s traditional local distribution company supplier.
A fracture created with little or no plastic deformation.
The part of a valve that packs off and encloses the valve stem.
Boe is a method of equating the energy produced by a hydrocarbon gas to a standard oil measurement.
One barrel of oil has about the same heat producing capacity as 6,000 ft3 of gas at standard conditions.
A part of the brake mechanism consisting of a flexible steel band lined with a material that grips a drum when tightened.
On a drilling rig, the brake band acts on the flanges of the drawworks drum to control the lowering of the traveling block and its load of drill pipe, casing, or tubing.
A device used to restrict fluid flow to one direction.
It consists of a polished sphere, or ball, usually or metal, and an annular piece, the seat, ground and polished to form a seal with the surface of the ball.
Gravitational force or the force of a spring holds the ball against the seat.
Flow in the direction of the force is presented, while flow in in the opposite direction overcomes the force and unseats the ball.
Abbreviation: barrels per day; often used in drilling reports