National Oilwell Varco 2011 Annual Report Download - page 25

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Index to Financial Statements
GLOSSARY OF OILFIELD TERMS
(Sources: Company management; A Dictionary for the Petroleum Industry, The University of Texas at Austin, 2001.)
API Abbr: American Petroleum Institute
Annular Blowout Preventer A large valve, usually installed above the ram blowout preventers, that forms a seal in the annular space between the pipe and
the wellbore or, if no pipe is present, in the wellbore itself.
Annulus The open space around pipe in a wellbore through which fluids may pass.
Automatic Pipe Handling
Systems (Automatic Pipe
Racker) A device used on a drilling rig to automatically remove and insert drill stem components from and into the hole. It replaces
the need for a person to be in the derrick or mast when tripping pipe into or out of the hole.
Automatic Roughneck A large, self-contained pipe-handling machine used by drilling crew members to make up and break out tubulars. The device
combines a spinning wrench, torque wrench, and backup wrenches.
Beam pump Surface pump that raise and lowers sucker rods continually, so as to operate a downhole pump.
Bit The cutting or boring element used in drilling oil and gas wells. The bit consists of a cutting element and a circulating
element. The cutting element is steel teeth, tungsten carbide buttons, industrial diamonds, or polycrystalline diamonds
(PDCs). These teeth, buttons, or diamonds penetrate and gouge or scrape the formation to remove it. The circulating
element permits the passage of drilling fluid and utilizes the hydraulic force of the fluid stream to improve drilling rates. In
rotary drilling, several drill collars are joined to the bottom end of the drill pipe column, and the bit is attached to the end of
the drill collars. Drill collars provide weight on the bit to keep it in firm contact with the bottom of the hole. Most bits used in
rotary drilling are roller cone bits, but diamond bits are also used extensively.
Blowout An uncontrolled flow of gas, oil or other well fluids into the atmosphere. A blowout, or gusher, occurs when formation
pressure exceeds the pressure applied to it by the column of drilling fluid. A kick warns of an impending blowout.
Blowout Preventer (BOP) Series of valves installed at the wellhead while drilling to prevent the escape of pressurized fluids.
Blowout Preventer (BOP) Stack The assembly of well-control equipment including preventers, spools, valves, and nipples connected to the top of the
wellhead.
Closed Loop Drilling Systems A solids control system in which the drilling mud is reconditioned and recycled through the drilling process on the rig itself.
Coiled Tubing A continuous string of flexible steel tubing, often hundreds or thousands of feet long, that is wound onto a reel, often dozens
of feet in diameter. The reel is an integral part of the coiled tubing unit, which consists of several devices that ensure the
tubing can be safely and efficiently inserted into the well from the surface. Because tubing can be lowered into a well without
having to make up joints of tubing, running coiled tubing into the well is faster and less expensive than running conventional
tubing. Rapid advances in the use of coiled tubing make it a popular way in which to run tubing into and out of a well. Also
called reeled tubing.
Cuttings Fragments of rock dislodged by the bit and brought to the surface in the drilling mud. Washed and dried cutting samples are
analyzed by geologist to obtain information about the formations drilled.
Directional Well Well drilled in an orientation other than vertical in order to access broader portions of the formation.
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