Definitions

A
abandon v: to temporarily or permanently cease production from a well or to cease further drilling   operations. [1]
abnormal pressure n: pressure outside the normal or expected range. [1]
abrasion n: wearing away by friction. [1]
acid fracture v: to part or open fractures in limestone formations by using fluid under hydraulic pressure. [1]
artificial lift: any method used to raise oil to the surface after a well ceases to flow. [3]
assignment: the legal instrument whereby Oil and Gas Leases are assigned/conveyed. [3]

B
bailer n: a long, cylindrical container fitted with a valve at its lower end, used to remove water, sand, mud, drilling cuttings, or oil from a well in cable-tool drilling. [1]
bent sub n: a short cylindrical device (generally angular) installed in the drill stem between the bottommost drill collar and a down hole motor. [1]
bit n: the cutting or boring element used in drilling oil and gas wells. [1]
blowout: an uncontrolled flow of gas, oil, or other well fluids from the well.
borehole: the hole created by the drilling of a well. [3]
bottomhole: the lowest or deepest part of a well. [3]
breakout block n: a plate that fits in the rotary table and holds the drill bit while it is being unscrewed from the drill collar. [1]

C
casing: steel pipe placed in an oil or gas well to prevent the wall of the hole from caving in, to prevent movement of fluids from one formation to another and to aid in well control. [3]
christmas tree: the arrangement of pipes and valves at the wellhead to control the flow of oil or natural gas and to prevent blowouts. [2]
compressor stations: stations located along natural gas pipelines which recompress gas to ensure an even flow. [2]
coring n: the process of cutting a vertical, cylindrical sample of the formations encountered as a well is drilled. [1]

D
daily drilling report: a record made each day of the operations on a working drilling rig and, traditionally, phoned, faxed, emailed, or radioed in to the office of the drilling company and possibly the operator every morning. [3]
dampener n: an air or inert gas device that minimizes pressure surges in the output line of a mud pump. Sometimes called a surge dampener. [1]
deed: written legal document by which the title to a property is transferred from on party to another. [3]
depletion: the value of a naturally occurring mineral deposit is a function of (1) the market value of the mineral, and (2) the concentration of the mineral in the mineral deposit. [3]
derrick/drilling rig: steel structure mounted over the borehole to support the drill pipe and other equipment that is lowered and raised during drilling operations. [2]
drill bit: tool used in drilling to break up rock mechanically in order to penetrate the subsoil. The bit drills a circular hole. [2]

E
electric cable tray n: supports the electrical cables that feed the power from the control panel to the rig motors. [1]
electric rig n: a drilling rig on which the energy from the power source—usually diesel engines—is changed to electricity by generators mounted on the engines. The electrical power is then distributed through electrical conductors to electric motors. The motors power the various rig components. [1]
erosion: the process by which material (such as rock or soil) is worn away or removed (as by wind or water). [3]

F
fastline: the end of the drilling line that is affixed to the drum or reel of the draw-works, so called because it travels with greater velocity than any other portion of the line. [3]
fishing n: the procedure of recovering lost or stuck equipment in the wellbore. [1]
flow n: a current or stream of fluid or gas. [1]
fracture n: a crack or crevice in a formation, either natural or induced. [1]
fracturing or fracking: the pumping of a media, typically water, sand and chemical additives, into a reservoir with a controlled force to fracture reservoir rock, resulting in a greater flow of natural gas or oil from the reservoir.
free-point indicator n: a device run on wireline into the wellbore and inside the fishing string and fish to locate the area where a fish is stuck. When the drill string is pulled and turned, the electromagnetic fields of free pipe and stuck pipe differ. The free-point indicator is able to distinguish these differences, which are registered on a metering device at the surface. [1]

G
gasket n: any material (such as paper, cork, asbestos, stainless steel or other types of metal, or rubber) used to seal two essentially stationary surfaces. [1]
gas lock n: 1. a condition sometimes encountered in a pumping well when dissolved gas, released from solution during the upstroke of the plunger, appears as free gas between the valves. If the gas pressure is sufficient, the standing valve is locked shut, and no fluid enters the tubing. 2. a device fitted to the gauging hatch on a pressure tank that enables manual dipping and sampling without loss of vapor. 3. a condition that can occur when gas-cut mud is circulated by the mud pump. The gas breaks out of the mud, expands, and works against the operation of the piston and valves. [1]
gathering: the process of collecting natural gas flowing from numerous wells and bringing it together into pooling areas where it is received into transmission pipelines. [2]
grantor: a person who grants or conveys lands,  minerals, etc. [3]
guide shoe n: 1. a short, heavy, cylindrical section of steel filled with concrete and rounded at the bottom, which is placed at the end of the casing string. It prevents the casing from snagging on irregularities in the borehole as it is lowered. [1]

H
horizontal drilling: the newer and developing technology that makes it possible to drill a well from the surface, vertically down to a certain level, and then to turn at a right angle, and continue drilling horizontally within a specified reservoir, or an interval of a reservoir. [3]
hydraulic adj: 1. of or relating to water or other liquid in motion. 2. operated, moved, or effected by water or liquid. [1]
hydraulic fracturing n: an operation in which a specially blended liquid is pumped down a well and into a formation under pressure high enough to cause the formation to crack open, forming passages through which oil can flow into the wellbore. [1]
hydraulic pumping n: a method of pumping oil from wells by using a downhole pump without sucker rods. Subsurface hydraulic pumps consist of two reciprocating pumps coupled and placed in the well. One pump functions as an engine and drives the other pump (the production pump). The downhole engine is usually operated by clean crude oil under under pressure (power oil) that is drawn from a power-oil settling tank by a triplex plunger pump on the surface. If a single string of tubing is used, power oil is pumped down the tubing string to the pump, which is seated in the string, and a mixture of power oil and produced fluid is returned through the casing-tubing annulus. If two parallel strings are used, one supplies power oil to the pump while the other returns the exhaust and produced oil to the surface. A hydraulic pump may be used to pump several wells from a central source. [1]

I
impeller: a set of mounted blades used to impart motion to a fluid air or gas (such as, the rotor of a  centrifugal pump). [3]
impression block n: a block with lead or another relatively soft material on its bottom. It is made up on drill pipe or tubing at the surface, run into a well, and set down on the object that has been lost in the well. The block is retrieved and the impression is examined. The impression is a mirror image of the top of the fish; it also indicates the fish’s position in the hole, for example, whether it is centered or off to one side. From this information, the correct fishing tool may be selected. [1]
induction log n: an electric well log in which the conductivity of the formation rather than the resistivity is measured. Because oil-bearing formations are less conductive of electricity than water-bearing formations, an induction survey, when compared with resistivity readings, can aid in determination of oil and water zones. [1]
insert n: 1. a cylindrical object, rounded, blunt, or chisel-shaped on one end and usually made of tungsten carbide, that is inserted in the cones of a bit, the cutters of a reamer, or the blades of a stabilizer to form the cutting element of the bit or the reamer or the wear surface of the stabilizer. Also called a compact. [1]
intake valve n: 1. the mechanism on an engine through which air and sometimes fuel are admitted to the cylinder. 2. on a mud pump, the valve that opens to allow mud to be drawn into the pump by the pistons moving in the liners. [1]

J
jar: a percussion tool operated manually or hydraulically to deliver a heavy upward or downward blow to fish stuck in the borehole. [3]
jet n: 1. a hydraulic device operated by a centrifugal pump used to clean the mud pits, or tanks, and to mix mud components. 2. in a perforating gun using shaped charges, a highly penetrating, fast-moving stream of exploded particles that forms a hole in the casing, cement, and formation. [1]
joint operating agreement: an agreement among working interest owners describing how a well is to be operated.[3]
junk n: metal debris lost in a hole. Junk may be a lost bit, pieces of a bit, pieces of pipe, wrenches, or any relatively small object that impedes drilling or completion and must be fished out of the hole. v: to abandon (as a nonproductive well). [1]
junk basket n: a device made up on the bottom of the drill stem or on wireline to catch pieces of junk from the bottom of the hole. Circulating the mud or reeling in the wireline forces the junk into a barrel in the tool, where it is caught and held. When the basket is brought back to the surface, the junk is removed. Also called a junk sub or junk catcher. [1]

K
kelly: the heavy square or hexagonal steel member suspended from the swivel through the rotary table and connected to the topmost joint of drill pipe to turn the drill stem as the rotary table turns. [3]
keyseat n: 1. an undergauge channel or groove cut in the side of the borehole and parallel to the axis of the hole. A keyseat results from the rotation of pipe on a sharp bend in the hole. 2. a groove cut parallel to the axis in a shaft or a pulley bore. [1]
kick n: an entry of water, gas, oil, or other formation fluid into the wellbore during drilling. It occurs because the pressure exerted by the column of drilling fluid is not great enough to overcome the pressure exerted by the fluids in the formation drilled. If prompt action is not taken to control the kick, or kill the well, a blowout may occur. [1]
kick fluids n pl: oil, gas, water, or any combination that enters the borehole from a permeable formation. [1]
kickoff point (KOP) n: the depth in a vertical hole at which a deviated or slant hole is started; used in directional drilling. [1]
kill v: 1. in drilling, to control a kick by taking suitable preventive measures (for example, to shut in the well with the blowout preventers, circulate the kick out, and increase the weight of the drilling mud). 2. in production, to stop a well from producing oil and gas so that reconditioning of the well can proceed. [1]

L
landman: the person who secures leases and handles damages for oil and gas companies who are drilling new wells or laying pipelines. [3]
landowner: The person who generally owns all or part of the minerals under his lands and is entitled to lease the same. [3]
land rig: any drilling rig that is located on dry land. [1]
lay n: 1. the spiral of strands in a wire rope either to the right or to the left, as viewed from above. 2. a term used to measure wire rope, signifying the linear distance a wire strand covers in one complete rotation around the rope. [1]
lease (oil & gas): a contract by which the owner of the mineral rights to a property conveys to another party, the exclusive right to explore for and develop minerals on the property, during a specified period of time. [3]
lessee: The person who purchases an Oil, Gas, and Mineral Lease. [3]
lessor: The party who grants an Oil, Gas, and Mineral Lease. [3]
liquefied natural gas: natural gas that has been cooled into a liquid state so that it takes up only 1/600 of the volume of natural gas. [2]
liquefied petroleum gas: propane, butane or propane-butane mixtures derived from crude oil refining or natural gas fractionation. For convenience of transportation, these gases are liquefied through pressurization.

M
mandrel n: a cylindrical bar, spindle, or shaft around which other parts are arranged or attached or that fits inside a cylinder or tube. [1]
mast n: a portable derrick that is capable of being raised as a unit, as distinguished from a standard derrick, which cannot be raised to a working position as a unit. For transporting by land, the mast can be divided into two or more sections to avoid excessive length extending from truck beds on the highway. [1]
master valve n: 1. a large valve located on the Christmas tree and used to control the flow of oil and gas from a well. Also called master gate. [1]
mill n: a down hole tool with rough, sharp, extremely hard cutting surfaces for removing metal, packers, cement, sand, or scale by grinding or cutting. [1]
mineral interest: an ownership of the minerals beneath a tract of land. If the surface ownership and the mineral ownership are different, the minerals are said to be “severed.” [2]
monkeyboard n: the derrickhand’s working platform. As pipe or tubing is run into or out of the hole, the derrickhand must handle the top end of the pipe, which may be as high as 90 feet (27 meters) or higher in the derrick or mast. [1]
mousehole n: shallow bores under the rig floor, usually lined with pipe, in which joints of drill pipe are temporarily suspended for later multiple completion n: an arrangement for producing a well in which one wellbore penetrates two or more petroleum-bearing formations. In one type, multiple tubing strings are suspended side by side in the production casing string, each a different length and each packed to prevent the commingling of different reservoir fluids. Each reservoir is then produced through its own tubing string. Alternatively, a small diameter production casing string may be provided for each reservoir, as in multiple miniaturized or multiple tubingless completions.connection to the drill string. [1]

N
natural gas: a mixture of hydrocarbon compounds and small amounts of various non-hydrocarbons (such as carbon dioxide, helium, hydrogen sulfide, and nitrogen) existing in the gaseous phase or in solution with crude oil in natural underground reservoirs. [3]
natural gas liquids: a general term for liquid products separated from natural gas in a gas processing plant. These include propane, butane, ethane and natural gasoline. [2]
nitro shooting n: a formation-stimulation process first used about 100 years ago in Pennsylvania. Nitroglycerine is placed in a well and exploded to fracture. [1]
nozzle n: 1. a passageway through jet bits that causes the drilling fluid to be ejected from the bit at high velocity. [1]

O
oil gravity: the density of liquid hydrocarbons, generally measured in degrees. [3]
operator: the party responsible for exploration, development or production projects. [2]
open formation n: a petroleum-bearing rock with good porosity and permeability. [1]
open hole n: 1. any wellbore in which casing has not been set. 2. open or cased hole in which no drill pipe or tubing is suspended. 3. the portion of the wellbore that has no casing. [1]
overshot n: a fishing tool that is attached to tubing or drill pipe and lowered over the outside wall of pipe or sucker rods lost or stuck in the wellbore. A friction device in the overshot, usually either a basket or a spiral grapple, firmly grips the pipe, allowing the fish to be pulled from the hole. [1]

P
packer n: a piece of downhole equipment that consists of a sealing device, a holding or setting device, and an inside passage for fluids. [1]
perforate v: to pierce the casing wall and cement of a wellbore to provide holes through which formation fluids may enter or to provide holes in the casing so that materials may be introduced into the annulus between the casing and the wall of the borehole. Perforating is accomplished by lowering into the well a perforating gun, or perforator. [1]
pilot n: a rodlike or tubelike extension below a downhole tool, such as a mill, that serves to guide the tool into or over another downhole tool or fish. [1]
pipeline: A string of interconnected pipe providing a route for natural gas to travel from the wellhead to market. Without pipelines, natural gas cannot be transported and sold at market to provide royalty payments, clean energy and economic benefits to the community. [2]
plug n: any object or device that blocks a hole or passageway (such as a cement plug in a borehole). [1]
pooling: a term frequently used interchangeably with “unitization;” more properly, it refers to the combining of small or irregular tracts into a unit large enough to meet state spacing regulations for drilling permits. “Unitization” is a term used to describe the combined operations of all or some portion of a producing reservoir.  [2]
porosity: a measurement of the number and size of the spaces between each particle in a rock.  Porosity affects the amount of liquid and gases, such as natural gas and crude oil, that a given reservoir can contain. [3]

R
rack n: 1. framework for supporting or containing a number of loose objects, such as pipe. See pipe rack. 2. a bar with teeth on one face for gearing with a pinion or worm gear. 3. a notched bar used as a ratchet. v: 1. to place on a rack. 2. to use as a rack. [1]
ream v: to enlarge the wellbore by drilling it again with a special bit. [1]
refracturing n: fracturing a formation again. [1]
reserves: the amount of oil or gas in a reservoir currently available for production, usually described as barrels of oil, or MCF. [3]
reservoirs: porous, permeable rock containing oil and natural gas; enclosed or surrounded by layers of less permeable or impervious rock. [2]
rig n: the derrick or mast, drawworks, and attendant surface equipment of a drilling or workover unit. [1]
royalty: the share of production or proceeds reserved to a mineral owner under the terms of a mineral lease. Normally, royalty interests are free of all costs of production except production taxes and transportation costs. It is established in the lease by reserving a royalty which is usually expressed as a fraction of production. [2]

S
safety clamp: a clamp placed tightly around a drill collar that is suspended in the rotary table by drill collar slips. [3]
severance tax: a tax due to the state on oil or gas produced or “severed” from the earth. [3]
shale n: a fine-grained sedimentary rock composed mostly of consolidated clay or mud. Shale is the most frequently occurring sedimentary rock. [1]
shut-in: an oil or gas well which is inactive. [3]
spud v: 1. to begin drilling a well; such as, to spud in. 2. to force a wireline tool or tubing down the hole by using a reciprocating motion. [1]
squeeze n: 1. a cementing operation in which cement is pumped behind the casing under high pressure to recement channeled areas or to block off an uncemented zone. [1]
substructure n: the foundation on which the derrick or mast and usually the drawworks sit; contains space for well control equipment. [1]

T
tally: to measure and record the total length or pipe, casing, or tubing that is to be run in a well. [3]
tank battery: tank batteries are part of the production equipment installed after a well is completed. They store the salt water that is returned from a producing well. [2]
tag line n: in crane and truck operations, a rope attached to the bottom of a load suspended by the crane or truck, which, when grasped by a crew member, allows the crew member to prevent rotation and to assist in guiding the load. [1]
tight formation n: a petroleum- or water-bearing formation of relatively low porosity and permeability. [1]
tracer n: a substance added to reservoir fluids to permit the movements of the fluid to be followed or traced. Dyes and radioactive substances are used as tracers in underground water flows and sometimes helium is used in gas. When samples of the water or gas taken some distance from the point of injection reveal signs of the tracer, the route of the fluids can be mapped. [1]
trip n: the operation of hoisting the drill stem from and returning it to the wellbore. v: to insert or remove the drill stem into or out of the hole. Shortened form of “make a trip.” [1]

U
unconsolidated formation n: a loosely arranged, apparently unstratified section of rock. [1]
unconventional resource: any area (shales, tight sands, fractured carbonates) where natural gas cannot be drilled and extracted vertically. [2]
undergauge bit n: a bit whose outside diameter is worn to the point at which it is smaller than it was when new. A hole drilled with an undergauge bit is said to be undergauge. [1]
unloading a well n: removing fluid from the tubing in a well, often by means of a swab, to lower the bottomhole pressure in the wellbore at the perforations and induce the well to flow. [1]

V
valve n: a device used to control the rate of flow in a line to open or shut off a line completely, or to serve as an automatic or semiautomatic safety device. Those used extensively include the check valve, gate valve, globe valve, needle valve, plug valve, and pressure relief valve. [1]
viscosity: a fluid’s resistance to flowing. [3]

W
wash over v: to release pipe that is stuck in the hole by running washover pipe. The washover pipe must have an outside diameter small enough to fit into the borehole but an inside diameter large enough to fit over the outside diameter of the stuck pipe. A rotary shoe, which cuts away the formation, mud, or whatever is sticking the pipe, is made up on the bottom joint of the washover pipe, and the assembly is lowered into the hole. Rotation of the assembly frees the stuck pipe. Several washovers may have to be made if the stuck portion is very long. [1]
well n: the hole made by the drilling bit, which can be open, cased, or both. Also called borehole, hole, or wellbore. [1]
wellhead: the control equipment fitted to the top of the well, consisting of outlets, valves, blowout-prevention equipment, etc. [2]
working interest: interest in a well which bears the cost of operations

Gas/Oil Terms
[1] United States Department of Labor – http://www.osha.gov/index.html
[2] Chesapeake Energy – http://www.chk.com/Pages/default.aspx
[3] Chestnut Petroleum, INC. – http://www.chestnutpetro.com/   

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