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Oil and Gas Well Drilling and Servicing eTool >> Glossary of Terms - P


*This is an abridged version of the Dictionary of Petroleum Terms provided by Petex and the
University of Texas Austin
© Petex 2001


n: a piece of downhole equipment that consists of a sealing device, a holding or setting device, and an inside passage for fluids.

packer fluid n: a liquid, usually salt water or oil, but sometimes mud, used in a well when a packer is between the tubing and the casing. Packer fluid must be heavy enough to shut off the pressure of the formation being produced, and should not stiffen or settle out of suspension over long periods of time, and must be non-corrosive.

packer squeeze method n: a squeeze cementing method in which a packer is set to form a seal between the working string (the pipe down which cement is pumped) and the casing. Another packer or a cement plug is set below the point to be squeeze-cemented. By setting packers, the squeeze point is isolated from the rest of the well.

packing n: 1. a material used in a cylinder on rotating shafts of an engine or pump in the stuffing box of a valve, or between flange joints to maintain a leak proof seal. 2. the specially fabricated filling in packed fractionation columns and absorbers.

packing assembly n: the arrangement of the downhole tools used in running and setting a packer.

packing elements n pl: the set of dense rubber, washer-shaped pieces encircling a packer, which are designed to expand against casing or formation face to seal off the annulus.

pack-off n: a device with an elastomer packing element that depends on pressure below the packing to effect a seal in the annulus. Used primarily to run or pull pipe under low or moderate pressures. Also called a stripper.

pack off v: to place a packer in the wellbore and activate it so that it forms a seal between the tubing and the casing.

paraffin n: a saturated aliphatic hydrocarbon having the formula CnH2n+2 (for example, methane, CH4; ethane, C2H6). Heavier paraffin hydrocarbons (for example, C18H38) form a waxlike substance that is called paraffin. These heavier paraffins often accumulate on the walls of tubing and other production equipment, restricting or stopping the flow of the desirable lighter paraffins.

paraffin scraper n: a tube with guides around it to keep it centered in the hole, and a cylindrical piece with blades attached. Spaces between the blades allow drilling fluid to pass through and carry away the scrapings.

parallel strings n pl: in a multiple completion, the arrangement of a separate tubing string for each zone produced, with all zones isolated by packers.

parted rods n pl: sucker rods that have been broken and separated in a pumping well because of corrosion, improper loading, damaged rods, and so forth.

PDC bit n: a special type of diamond drilling bit that does not use roller cones.

penetration rate n: see rate of penetration.

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.

perforated completion n: 1. a well completion method in which the producing zone or zones are cased through, cemented, and perforated to allow fluid flow into the wellbore. 2. a well completed by this method.

perforated liner n: a liner that has had holes shot in it by a perforating gun.

perforated pipe n: sections of pipe (such as casing, liner, and tail pipe) in which holes or slots have been cut before it is set.

perforating gun n: a device fitted with shaped charges or bullets that is lowered to the desired depth in a well and fired to create penetrating holes in casing, cement, and formation.

perforation n: a hole made in the casing, cement, and formation through which formation fluids enter a wellbore. Usually several perforations are made at a time.

perforation depth control log (PDC log) n: a special type of nuclear log that measures the depth of each casing collar. Knowing the depth of the collars makes it easy to determine the exact depth of the formation to be perforated by correlating casing-collar depth with formation depth.

perforator n: see perforating gun.

permanent packer n: a nonretrievable type of packer that must be drilled or milled out for removal.

permeability n: 1. a measure of the ease with which a fluid flows through the connecting pore spaces of a formation or cement. The unit of measurement is the millidarcy. 2. fluid conductivity of a porous medium. 3. ability of a fluid to flow within the interconnected pore network of a porous medium.

petroleum n: a substance occurring naturally in the earth in solid, liquid, or gaseous state and composed mainly of mixtures of chemical compounds of carbon and hydrogen, with or without other nonmetallic elements such as sulfur, oxygen, and nitrogen. In some cases, especially in the measurement of oil and gas, petroleum refers only to oil—a liquid hydrocarbon—and does not include natural gas or gas liquids such as propane and butane.

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.

pilot bit n: a bit placed on a special device that serves to guide the device into an already existing hole that is to be opened (made larger in diameter). The pilot bit merely guides, or pilots, the cutters on the hole opener into the existing hole so that the hole-opening cutters can enlarge the hole to the desired size.

pilot mill n: a special mill that has a heavy tubular extension below it called a pilot or stinger. The pilot, smaller in diameter than the mill, is designed to go inside drill pipe or tubing that is lost in the hole. It guides the mill to the top of the pipe and centers it, thus preventing the mill from by-passing the pipe. Also called a piloted mill.

pinch points n: the sections where body parts or other materials may be pinched.

Pipe Ramppipe ramp and pipe on rack n: an angled ramp for dragging drill pipe, casing and other materials up to the drilling floor or bringing such equipment down.

pick up
v: 1. to use the drawworks to lift the bit (or other tool) off bottom by raising the drill stem. 2. to use an air hoist to lift a tool, a joint of drill pipe, or other piece of equipment.

n: 1. the male threaded section of a tool joint. 2. on a bit, the threaded bit shank.

n: a long, hollow cylinder, usually steel, through which fluids are conducted. Oilfield tubular goods are casing (including liners), drill pipe, tubing, or line pipe.

Pipe Rackpipe racks n pl: horizontal supports for tubular goods.

pipe racker n: 1. (obsolete) a worker who places pipe to one side in the derrick. 2. a pneumatic or hydraulic device used to mechanize the rig floor.

pipe ram
n: a sealing component for a blowout preventer that closes the annular space between the pipe and the blowout preventer or wellhead.

pipe ram preventer
n: a blowout preventer that uses pipe rams as the closing elements. See pipe ram.

pipe tongs
n pl: see tongs.

pipe upset n: that part of the pipe that has an abrupt increase of dimension.

pipe wiper
n: a flexible disk-shaped device, usually made of rubber, with a hole in the center through which drill pipe or tubing passes. It is used to wipe off mud, oil, or other liquid from the pipe as it is pulled from the hole.

pit level
n: height of drilling mud in the mud tanks, or pits.

pit-level indicator
n: one of a series of devices that continuously monitor the level of the drilling mud in the mud tanks. The indicator usually consists of float devices in the mud tanks that sense the mud level and transmit data to a recording and alarm device (a pit-volume recorder) mounted near the driller’s position on the rig floor. If the mud level drops too low or rises too high, the alarm may sound to warn the driller of lost circulation or a kick.

pitman n: the arm that connects the crank to the walking beam on a pumping unit by means of which rotary motion is converted to reciprocating motion.

plug n: any object or device that blocks a hole or passageway (such as a cement plug in a borehole).

plug and abandon (P&A)
v: to place cement plugs into a dry hole and abandon it.

plug back v: to place cement in or near the bottom of a well to exclude bottom water, to sidetrack, or to produce from a formation higher in the well. Plugging back can also be accomplished with a mechanical plug set by wireline, tubing, or drill pipe.

plug-back cementing n: a secondary cementing operation in which a plug of cement is positioned at a specific point in the well and allowed to set.

plunger n: 1. a basic component of the sucker rod pump that serves to draw well fluids into the pump. 2. the rod that serves as a piston in a reciprocating pump. 3. the device in a fuel-injection unit that regulates the amount of fuel pumped on each stroke.

pole mast n: a portable mast constructed of tubular members. A pole mast may be a single pole, usually of two different sizes of pipe telescoped together to be moved or extended and locked to obtain maximum height above a well. Double-pole masts give added strength and stability. See mast.

polished rod n: the topmost portion of a string of sucker rods. It is used for lifting fluid by the rod-pumping method. It has a uniform diameter and is smoothly polished to seal pressure effectively in the stuffing box attached to the top of the well.

polycrystalline diamond compact (PDC) n: a disk (a compact) of very small synthetic diamonds, metal powder, and tungsten carbide powder that are used as cutters on PDC bits.

porosity n: 1. the condition of being porous (such as a rock formation). 2. the ratio of the volume of empty space to the volume of solid rock in a formation, indicating how much fluid a rock can hold.

portable mast n: a mast mounted on a truck and capable of being erected as a single unit. See telescoping mast.

possum belly n: 1. a receiving tank situated at the end of the mud return line. The flow of mud comes into the bottom of the device and travels to control mud flow over the shale shaker. 2. a metal box under a truck bed that holds pipeline repair tools.

Engine Generator Setspower generating system n: a diesel, LPG, natural gas, or gasoline engine along with a mechanical transmission or generator for producing power for the drilling rig.

power wrench n: a wrench that is used to make up or break out drill pipe, tubing, or casing on which the torque is provided by air or fluid pressure. Conventional tongs are operated by a mechanical pull provided by a jerk line connected to a cathead.

preflush n: 1. an injection of water prior to chemical flooding that is used to induce reservoir conditions favorable to the surfactant solution by adjusting reservoir salinity and reducing ion concentrations. A preflush may also be used to obtain advance information on reservoir flow patterns. 2. fluid injected prior to the acid solution pumped into a well in an acid-stimulation treatment; sometimes called a spearhead. Compare overflush.

pressure depletion n: the method of producing a gas reservoir that is not associated with a water drive. Gas is removed and reservoir pressure declines until all the recoverable gas has been expelled.

preventer n: shortened form of blowout preventer. See blowout preventer.

preventive maintenance
n: a system of conducting regular checks, routine maintenance and testing of equipment to lengthen the service life and to potentially permit replacement or repair of weakened or faulty parts before equipment failure results.

primary recovery n: the first stage of oil production in which natural reservoir drives are used to recover oil, although some form of artificial lift may be required to exploit declining reservoir drives.

n: 1. the phase of the petroleum industry that deals with bringing the well fluids to the surface and separating them and storing, gauging, and otherwise preparing the product for delivery. 2. the amount of oil or gas produced in a given period.

production casing
n: the last string of casing set in a well, inside of which is usually suspended a tubing string.

production maintenance
n: the efforts made to minimize the decline in a well’s production. It includes, for example, acid-washing of casing perforations to dissolve mineral deposits, scraping or chemical injection to prevent paraffin buildup, and various measures taken to control corrosion and erosion damage.

production packer n: any packer designed to make a seal between the tubing and the casing during production.

production rig n: a portable servicing or workover unit, usually mounted on wheels and self-propelled. A wellservicing unit consists of a hoist and engine mounted on a wheeled chassis with a self-erecting mast. A workover rig is basically the same, with the addition of a substructure with rotary, pump, pits, and auxiliaries to permit handling and working a drill string.

production test n: a test of the well’s producing potential usually done during the initial completion phase.

production tubing n: a string of tubing used to produce the well.

production well
n: in fields in which improved recovery techniques are being applied, the well through which oil is produced.

productivity test n: a combination of a potential test and a bottomhole pressure test the purpose of which is to determine the effects of different flow rates on the pressure within the producing zone of the well to establish physical characteristics of the reservoir and to determine the maximum potential rate of flow.

propping agent n: a granular substance (sand grains, aluminum pellets, or other material) that is carried in suspension by the fracturing fluid and that serves to keep the cracks open when fracturing fluid is withdrawn after a fracture treatment.

pulling unit n: a well-servicing outfit used in pulling rods and tubing from the well. See production rig.

pulsed neutron logging device n: a measuring instrument run inside casing to obtain an indication of the presence or absence of hydrocarbons outside the casing, to determine water saturation in a reservoir behind casing, to detect water movement in the reservoir, to estimate porosity, and to estimate water salinity.

pulsed-neutron survey n: a special cased hole logging method that uses radioactivity reaction time to obtain measurements of water saturation, residual oil saturation, and fluid contacts in the formation outside the casing of an oil well.

pump n: a device that increases the pressure on a fluid or raises it to a higher level. Various types of pumps include the bottom hole pump, centrifugal pump, hydraulic pump, jet pump, mud pump, reciprocating pump, rotary pump, sucker rod pump, and submersible pump.

pump barrel n: the cylinder or liner in which the plunger of a sucker rod pump reciprocates.

pump-down adj: descriptive of any tool or device that can be pumped down a wellbore. Pump-down tools are not lowered into the well on wireline; instead, they are pumped down the well with the drilling fluid.

pumping unit n: the machine that imparts reciprocating motion to a string of sucker rods extending to the positive displacement pump at the bottom of a well. It is usually a beam arrangement driven by a crank attached to a speed reducer, coupled to a motor.

pump jack n: a surface unit similar to a pumping unit but having no individual power plant. Usually, several pump jacks are operated by pull rods or cables from one central power source.

pump rate n: the speed, or velocity, at which a pump is run. In drilling, the pump rate is usually measured in strokes per minute.

pup joint n: a length of drill or line pipe, tubing, or casing shorter than range 1 (18 feet or 6.26 meters for drill pipe) in length.

pusher n: shortened form of toolpusher.


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