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Discover the IHRDC Energy Glossarybeta

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W

wackestone

A mud-supported carbonate rock with scattered grains, typically poor reservoir.

Wadati-Benioff zone

The dipping plane of earthquakes that traces a subducting slab, named for the seismologists Kiyoo Wadati and Hugo Benioff.

wage and hour law

The statutory rules on minimum pay, overtime and hours worked.

wait on cement (WOC)

The period after a cement job during which operations stop while the cement develops strength, abbreviated WOC.

wait time

The interval allowed before an NMR measurement so protons can realign with the static field, abbreviated TW.

walk-above vertical seismic profile (VSP)

A VSP in a deviated well where the source is moved along the surface to stay directly above each receiver position.

walkaway

A vertical seismic profile recorded with the source moved progressively away from the well.

walkaway vertical seismic profile (VSP)

A VSP with the receivers fixed in the well and the source moved out to progressively longer offsets.

walkie

A type of motor-driven pallet jack that the operator walks along with to guide and control.

walking away

Ending negotiation and taking the alternative, credible only if the alternative is real.

wall cake

The layer of solids deposited on the borehole wall as filtrate is forced into a permeable formation.

wall loss

Reduction of casing or tubing wall thickness by corrosion or erosion, inside or out.

wall sticking

Differential sticking, in which the string is pinned against the filter cake by the pressure difference into a permeable zone.

wall-fired furnace

A furnace that has burners installed along the shell walls.

WALPG (law, accounting and finance simulation)

The law, accounting and finance simulation, evaluating an energy project in a hypothetical West African country.

Walsh-Hadamard transform

A transform onto square-wave basis functions, computed by addition and subtraction alone with no multiplication.

Walther's law

The principle that facies succeeding one another vertically without a break must have been deposited in laterally adjacent environments.

WANOCO (West African NOC simulation)

The simulation in which teams grow the international arm of a West African national oil company.

warehouse management system (WMS)

The software directing receipt, putaway, picking and dispatch.

warehouse productivity

Output per labor hour or per square meter in the warehouse.

warmth and strength

The two dimensions on which people instinctively judge others, and which leaders must balance.

warmup

Bringing equipment gradually to operating temperature so it expands evenly.

warmup burner

A burner that is used to increase boiler temperature during the warmup stage of startup.

warning signs of violent behaviour

The observable changes that often precede an incident and allow intervention.

warranty

A contractual promise about quality or condition, breach of which sounds in damages.

wash pipe

The inner string run inside a screen or through a washover shoe to carry returns during placement or washover.

washer

A flat thin ring or a perforated plate used in joints or assemblies to ensure tightness, prevent leakage, or relieve friction.

washout

An enlargement of the borehole beyond the bit size, caused by erosion or by the formation caving.

washover

A fishing operation in which a hollow mill is run over the outside of a stuck fish to free it.

washover pipe

The large-diameter pipe run over a fish during a washover, with a cutting shoe at its base.

washover shoe

A cutting shoe on the bottom of washpipe, run over a stuck fish to cut away the material holding it.

waste activated sludge

Sludge that is removed and disposed of during the activated sludge process.

waste disposal

Getting waste away in a lawful and documented way.

waste minimization

Eliminating activity that consumes resources without adding value.

wastewater

Water left over from a process that may be contaminated with pollutants.

wastewater cleanup

Removing solids and contaminants from used water so it can be returned to the mud system or discharged.

wastewater treatment

Treating plant effluent to a standard permitting discharge.

wastewater treatment system

The equipment treating effluent to a dischargeable standard.

water alternating gas (WAG)

Injecting slugs of water and gas in turn, so the water controls the mobility of the gas ahead of it, abbreviated WAG.

water base mud

A drilling fluid in which water is the major liquid phase, as well as the wetting phase.

water base mud, water base drilling fluid

A water base mud is a drilling fluid in which water is the major liquid phase, as well as the wetting phase.

water block

A reduction in permeability to hydrocarbon caused by water saturation raised in the near-wellbore rock, usually by filtrate invasion.

water bottom roll

A pseudo-Rayleigh wave travelling along the water-seafloor interface, seen as strong low-frequency noise on marine records.

water breakthrough

Water breakthrough is a description of reservoir conditions under which a fluid, previously isolated or separated from production, gains access to a producing wellbore. The term is most commonly applied to water or gas breakthrough, where the water or gas injected to maintain reservoir pressure via injection wells breaks through to one or more of the producing wells.

water circulating pump

The pump moving water round a circuit.

water clarification

Removing suspended and colloidal solids from water, usually by coagulation and flocculation before filtration.

water coning

The upward pull of the oil-water contact toward a producing well under drawdown, until water is produced.

water contact

The elevation above which fluids other than water, such as oil and gas, can be found in the pores of a rock.

water control

Any treatment intended to cut unwanted water production while preserving hydrocarbon flow.

water cooling

Rejecting heat to water rather than to air, giving lower temperatures where water is available.

water cushion

A water cushion is a volume of water placed in a tubing string prior to conducting a drill stem test or opening a well to flow with a formation tester. The water cushion is designed to reduce and control the pressure drawdown applied to the reservoir when the downhole valve or tester valve is opened to initiate flow.

water cut

Water cut is the ratio of water produced compared to the volume of total liquids produced.

water dew point

The temperature at which water starts to condense from gas, the limit sales contracts set.

water disposal

Getting produced water away, by injection or treatment, and often the constraint on production rate.

water disposal system

The pumps, lines and wells taking produced water away.

water draw method

The method used to calibrate a physical prover. Water flows into a calibrated container as the displacer makes a trip.

water drive

Water drive is a reservoir drive mechanism whereby the oil is driven through the reservoir by an active aquifer.

water droplet

A drop of water dispersed in another phase.

water dump valve

Automatic valve discharging separated water when the level controller calls for it.

water electrolysis

Splitting water electrically to hydrogen and oxygen, distinguished from chlor-alkali routes that yield it as byproduct.

water flood

Water flood is a method of secondary hydrocarbon recovery in which water is injected into the reservoir formation to displace some of the residual oil.

water flood, waterflood

Water flood is a method of secondary hydrocarbon recovery in which water is injected into the reservoir formation to displace some of the residual oil.

water flood, waterflood, water injection

Water flood is a method of secondary hydrocarbon recovery in which water is injected into the reservoir formation to displace some of the residual oil.

water formation volume factor

The volume a barrel of stock tank water occupies at reservoir conditions, symbol Bw.

water glycol

A water and glycol mixture, whose freezing point is below either component alone.

water gun

A marine seismic source that fires a slug of water into the sea, creating an implosion rather than an expanding bubble.

water hammer

The slamming of accumulated condensate against a piping wall.

water holdup

The fraction of pipe cross-section occupied by water in multiphase flow.

water influx

The movement of aquifer water into a reservoir as its pressure falls, replacing the volume produced.

water inlet

The connection water enters by.

water loss

The volume of filtrate a mud gives up in the standard API filtration test.

water mud

A drilling fluid whose continuous phase is water or brine.

water outlet

The connection water leaves by.

water production

The volume of water produced with the oil or gas.

water reactive chemicals

Chemicals that will react with water to release a gas that is either flammable or presents a health hazard.

water resistivity

The electrical resistivity of formation water, a required input to the saturation calculation.

water salinity

The dissolved salt content of formation water, which must be known before a resistivity log means anything.

water saturation

The fraction of water in a given pore space, expressed in volume/volume, percent, or saturation units. Unless otherwise stated, water saturation refers to the fraction of formation water in the undisturbed zone, corresponding to the effective porosity.

water seal

A type of turbine seal that uses water to fill the opening between the turbine shaft and the casing to prevent leakage.

water siphon

The device by which the water level in the unit is maintained.

water testing

Testing the mechanical integrity of a tank by filling the tank with water and then checking the tank for leaks or other signs of damage; also called hydroelectric or hydro testing.

water tube

A tube through which water and steam are distributed in a water tube boiler.

water tube boiler

A type of boiler in which tubes are used to transport water and steam.

water tube boilers

A type of boiler in which tubes are used to transport water and steam.

water valve

A valve on water service.

water vapor

Water in a gaseous form. Water can exist in three phases: gas, liquid, and solid.

water vapour

Water in gas phase, which must be removed before it condenses or freezes downstream.

water wash

A piece of equipment in which water is mixed with neutralized reactor effluent to absorb entrained caustic.

water, oil, and solids test

The retort test that splits a mud sample into its water, oil and solids fractions by distillation.

water-based drilling fluid

A drilling fluid whose continuous phase is fresh water, seawater or brine.

water-based mud

A drilling fluid built on water or brine as its continuous phase, with clays and polymers giving it its properties.

water-cut meter

A device that infers water holdup from the capacitance or impedance of the produced fluid.

water-filled resistivity

The resistivity a formation would have if all its pore space were filled with formation water, symbol Ro.

water-flow log

A log of water velocity and direction in or behind the casing, from the oxygen activation of the water itself.

water-in-oil emulsion

An emulsion with water droplets dispersed through a continuous oil phase.

water-mud emulsifier

The surfactant that keeps oil dispersed as fine droplets through a water-base mud.

water-reactive

A chemical that reacts with water to release a gas that is either flammable or presents a health hazard.

water-to-cement ratio

The mass of mix water per unit mass of cement, usually quoted as a percentage.

water-wet

The tendency of one fluid to spread on, or adhere to, a solid surface in the presence of other immiscible fluids. Many rocks are water-wet. A water-wet area contains profuse amounts of water but no recoverable hydrocarbons.

water-wet formation

In water-wet formations, a thin film of water coats the surface of the formation matrix.

water/oil interface

The level at which the layers of water and crude meet in a desalter.

water/oil ratio (WOR)

The volume of water produced per volume of oil, abbreviated WOR.

waterfall

Sequential delivery where each phase completes before the next begins.

Waterfall vs. Agile

Fixed scope with variable time against fixed time with variable scope.

waterflood

An improved oil recovery technique that involves injecting water into a producing reservoir to increase production and enhance movement of oil to producing wells. Use of water to increase oil production is known as secondary recovery.

waterflood kick

The first rise in oil production that shows a waterflood is working — fill-up is complete and the oil bank has arrived.

waterflood recovery

The additional oil produced by injecting water into the reservoir.

waterflooding

Injecting water into a reservoir to maintain pressure and sweep oil toward the producers.

waterwall

The boiler furnace wall made of water-filled tubes, which absorbs radiant heat.

waterwall tube

A tube forming the water-cooled wall of a boiler furnace.

waterwalls

Vertical tubes, filled with a water/steam mixture, that line the inside of a boiler furnace.

watson K factor (UOP)

A calculated index placing a crude on the scale from paraffinic to aromatic.

watt

The unit of electric power, equal to the rate of energy transfer when one ampere of current flows through an electrical potential difference of one volt at unity power factor.

watt-hour

The basic unit used to measure electrical energy. Watt-hours are determined by multiplying power by time. One watt-hour is the amount of energy used when one watt of power is delivered to an electrical device for one hour.

watt-hour (wh)

An electrical energy unit of measure equal to 1 watt of power supplied to, or taken from, an electric circuit steadily for 1 hour.

wave

A disturbance that carries energy through a medium by displacing its particles about their rest positions.

wave equation

The partial differential equation relating a wavefield's variation in space to its variation in time through the propagation velocity.

wave propagation

The travel of a disturbance through a medium.

wave swash

Wave swash refers to the movement of water from a wave that breaks onto a beach and then recedes back into the sea. Swash is a dynamic process that involves both an uprush (onshore flow) and a backwash (offshore flow).

wave velocity

The speed a wave travels at in a medium.

wavefield

The complete pattern of wave motion in the subsurface at a given instant.

waveform

A graphic representation of a voltage varying over time.

waveform analysis

Waveform analysis is the determination of the amplitude and phase of the components of a complex waveform, either mathematically or by means of electronic instruments.

wavefront

The surface joining all points of a propagating wave that are at the same phase.

wavelength

The distance between successive corresponding points of a wave, equal to velocity divided by frequency.

wavelet

A short oscillating pulse of finite length, used to represent the seismic source and the basic reflection response.

wavelet extraction

Deriving the embedded wavelet from the seismic data itself, usually by comparing it against a known reflectivity series at a well.

wavelets transform

A wavelet transform creates a representation of the signal in both time and frequency domains, which allows efficient access of localized information about the signal.

wavenumber

The number of wave cycles per unit distance, the spatial counterpart of frequency, symbol k.

waxman-smits

The saturation equation accounting for the conductivity clay contributes in shaly sands.

waxy

Containing enough paraffin wax to gel or deposit as the crude cools.

weak point

A deliberately weakened section of cable or rope head, designed to part at a known tension so the line can be recovered if the tool sticks.

weak point, weakpoint

The weak point is a piece of steel cable placed inside a logging head that is designed to break at a pre-determined tension. If the logging tool becomes stuck in the borehole, there is a danger that the logging cable will break at surface, since this is the place of maximum tension. It is difficult to fish a long length of tangled cable in the borehole. The weak point is designed to break before the cable, so that the latter can be retrieved, leaving only the logging tool and head in the borehole.

wearing ring

A replaceable ring that can be mounted on either the impeller or the casing of a centrifugal pump; designed to prevent leakage from the volute back to the suction eye.

wearing rings

Replaceable rings on the casing or the impeller of a centrifugal pump that wear as the pump operates.

weathered layer

The low-velocity surface layer whose variable thickness and velocity distort seismic traveltimes.

weathering

The breakdown of rock at and near the surface by physical, chemical and biological processes.

weathering correction

The time shift applied to seismic data to remove the delay caused by the low-velocity near-surface layer.

weathering layer

A weathering layer is a rock layer at or near the surface, usually marked by a sharp transition, in which the seismic velocities are substantially lower than in the less weathered, hard rock layers beneath it.

web analytics

Measuring site traffic and behavior to understand what visitors actually do.

Web Content Accessibility Guidelines (WCAG)

The international standard for accessible web content, cited in most procurement requirements.

webinar

A digital seminar where presenters discuss a specific subject, reaching viewers worldwide. Participants can either join these sessions live or view the recorded version at a later time at their convenience.

wedge gate

A gate valve closure member tapered so that closing thrust drives it hard against matching inclined seats.

weevil

Rig slang for a new and inexperienced hand, short for boll weevil.

weight

The downward force exerted by an object as a result of gravity.

weight indicator

The driller's gauge showing hook load, and by difference the weight being carried by the bit.

weight material

A dense, finely ground solid added to raise a fluid's density.

weight transference

The temporary movement of a forklift's center of gravity due to changes in momentum.

weighted average

An average in which each value counts in proportion to its size or importance.

weighted mud

A mud whose density has been raised above that of its base fluid by adding barite or another weighting material.

weighting agent

Another term for weighting material — the dense solid used to increase fluid density.

weighting material

The dense inert solid, usually barite, added to a drilling fluid to raise its density.

weir

A dam-like device or flat restriction installed across a channel to maintain and control liquid level and flow. In metering, a notched restriction that causes liquid level to rise for conversion to a flow rate. In glycol systems, a dam in the contactor or reboiler that holds glycol level above bubble cap slots or fire tubes.

welder

The person or machine making a welded joint.

welding

A process in which heat is used to melt metal surfaces for the purpose of joining them together.

welding machine

The power source supplying and controlling current for welding.

well cleanup

The initial flow period during which drilling and completion debris is produced back before the well settles down.

well completion

The process of making a well ready for production or injection after drilling operations.

well control

The set of practices and equipment that keep formation fluids from entering the well uncontrolled.

well flow rate

The rate at which a well produces or takes fluid.

well interference

The pressure change at one well caused by production or injection at another.

well interference testing

A test in which one well's rate is changed and the pressure response is watched in another, to establish whether they are connected.

well kick

A kick is a well control problem in which the pressure found within the drilled rock is higher than the mud hydrostatic pressure acting on the borehole or rock face. When this occurs, the greater formation pressure tends to force formation fluids into the wellbore. This forced fluid flow is called a kick.

well log

A record of one or more measured properties against depth in a well.

well log correlation

Well log correlation is the identification and connection of equivalent patterns and/or values between log curves of adjacent wells.

well logging

Running instruments down a borehole to measure the properties of the formations penetrated.

well logging, geological well logging

Well logging is the practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole. The log may be based either on visual inspection of samples brought to the surface or on physical measurements made by instruments lowered into the hole.

well logging, geological well logging, well logs

The practice of making a detailed record (a well log) of the geologic formations penetrated by a borehole, based either on visual inspection of samples brought to the surface (mud log) or on physical measurements made by instruments lowered into the hole (wireline logging or logging while drilling).

well placement

The steering of a wellbore to land and stay within a chosen part of the reservoir.

well plan

The approved document specifying a well's trajectory, casing, mud, evaluation and completion program.

well potential

The rate a well is capable of producing under its best achievable conditions.

well production rate

The volume of fluid a well delivers per unit time.

well prognosis

A well prognosis is a detailed description of the likely geological sequence to be encountered in the well, together with associated data acquisition objectives and operational procedures.

well program

The engineered plan for a well: depths, casing, mud, logging and expected costs.

well servicing

Routine maintenance work on a producing well, done with a service rig or lighter equipment rather than a drilling rig.

well shoot

A borehole seismic survey measuring traveltime from a surface source to known depths in the well.

well stimulation

A treatment performed to enhance the productivity of a well, by either hydraulic fracturing or matrix treatments.

well stream

All fluids produced at the wellhead, e.g., gas, liquid vapors, water, oil, etc.

well terminology

An Exploration Well is the first well drilled on an exploration prospect. If there is a discovery then several Appraisal Wells (or Delineation Wells) are drilled to confirm the extent of the discovery, the size of the reservoir and the quality of reservoir environment. These wells are typically drilled vertically. In offshore prospects, they are often abandoned after drilling the appraisal wells.

well test

The measurement of production from a well in a given length of time under controlled conditions.

well testing

Well testing is the execution of data acquisition activities to broaden the knowledge and understanding of hydrocarbons properties and characteristics of the reservoir. The test will also provide information about the state of the particular well tested. The overall objective is identifying the reservoir's capacity to produce hydrocarbons.

well tractors

A well tractor is a self-propelled robotic device used in highly deviated wellbores to drive tools down towards the toe of the well.

wellbore

The hole drilled by a drilling rig to explore for or develop oil and/or natural gas. Also referred to as a well or borehole.

wellbore breakout

Failure of the hole wall in compression, which enlarges the hole along the least stress direction.

wellbore damage

Any near-wellbore reduction in flow capacity, from invasion, fines migration, scale or crushed perforations.

wellbore deviation

Departure of the hole from vertical, deliberate or otherwise.

wellbore diagram

A scaled schematic of a well showing casing, tubing, packers, nipples and every other component with its depth.

wellbore environment

The pressure, temperature and fluid conditions inside the hole.

wellbore fill-up

The continued flow into a well after it is shut in at surface, as the compressed fluid in the wellbore expands and the level rises.

wellbore fluid

Whatever fluid occupies the hole, whether mud, brine or produced fluid.

wellbore instability

The hole failing to stay open, from stress, chemical attack or wrong mud weight.

wellbore orientation

The direction of a wellbore, given as an inclination from vertical and an azimuth.

wellbore pressure

The fluid pressure inside the hole, balanced against formation pressure during drilling.

wellbore radius

The hole radius, a term in every inflow equation.

wellbore stability

Whether the hole stays open, set by mud weight against rock strength and stress.

wellbore storage

Wellbore storage is the afterflow of fluids into the well bore after the well is shut-in at the wellhead. During wellbore storage, reservoir effects are masked or distorted, making it impossible to quantify well properties such as permeability, skin and P*.

wellbore storage effects

The early-time distortion of a pressure test caused by fluid compressing or the level moving in the wellbore rather than by reservoir flow.

wellbore wall

The exposed rock surface of the drilled hole.

wellhead

The stack of casing heads, spools and hangers at surface that suspends the strings and seals the annuli.

wellhead backpressure

The pressure held at the wellhead against the flowing well by the choke and the downstream system.

wellhead equipment

The valves and spools controlling and sealing the well at surface.

wellhead flowing pressure

The pressure at surface while the well produces.

wellhead pressure

The pressure measured at surface, from which downhole conditions are inferred.

wellness program

Employer-provided activities and support intended to improve employee health.

wellsite

The prepared location where the rig and its support equipment stand.

wellsite geologist

A specialist who analyzes samples from an oil well as it is being drilled, recommends decisions on coring, reports on hydrocarbon shows, and liaises with drilling engineers and the company office.

welte

Co-author of the standard text on petroleum formation and occurrence.

Wentworth scale

The Udden-Wentworth grade scale, classifying sediment by grain diameter in doubling steps from clay through silt and sand to gravel.

West Texas Intermediate (WTI)

The light sweet US crude that serves as the North American price benchmark.

Western Union splice

A type of splice that is often used to join small, solid conductors together in a linear run.

wet air receiver

Air receiver upstream of the dryer, where condensed moisture collects and is drained.

wet chemistry

See Intermittent monitoring.

wet combustion

In-situ combustion with water injected alongside or alternating with the air.

wet gas

Natural gas that contains an appreciable amount of heavier hydrocarbons (natural gas liquids), which are often liquid.

wet glycol (or rich glycol)

Glycol that has absorbed water.

wet oil

Oil still carrying basic sediment and water above the sales specification.

wet scrubber

A scrubber that uses a liquid to remove contaminants from a gas or vapor stream.

wet-clay porosity

The fraction of a wet clay's volume occupied by clay-bound water.

wet-type filter

A filter that is coated with a sticky substance that holds contaminants against the filter material; also called an adhesive-type filter.

wettability

The tendency of a liquid to spread on, or adhere to, a solid surface in the presence of other immiscible fluids.

wettability change

Formation damage in which the rock's surface preference shifts, usually from water-wet toward oil-wet, altering relative permeability.

wettability, oil-wet, water-wet

Wettability is the tendency of one fluid to spread on, or adhere to, a solid surface in the presence of other immiscible fluids. Rocks can be oil-wet or water-wet.

wettability, water wet, oil wet

Wettability is the tendency of one fluid to spread on, or adhere to, a solid surface in the presence of other immiscible fluids.

wetting

The tendency of one fluid to spread on the rock surface in preference to another.

wetting phase

The fluid preferentially coating the rock, which occupies the small pores and moves last.

wheel

In a turbine, a round hub containing a set of rotating blades.

whipstock

A whipstock is a curved steel wedge used in drilling operations to start a new branch of a well, or wellbore, or to deflect the drill bit for directional drilling.

whistleblowing

Reporting wrongdoing, internally or externally, and the protection owed to the reporter.

whole core

A full-diameter cylinder of rock cut with a core barrel, as opposed to a plug or a sidewall sample.

whole number

A number that describes a whole object or an entire quantity.

whole-mud dilution

Controlling solids by dumping part of the active system and replacing the volume with fresh mud.

Whole-Part-Whole learning

Showing the complete picture, teaching the components, then reassembling them.

wholesale market

The market in which bulk product is traded before retail distribution.

wholesale price

The bulk price at which product is sold before retail distribution.

wide-azimuth towed-streamer acquisition

Marine acquisition using separate source and streamer vessels so that a wide range of source-receiver azimuths is recorded.

wiggle trace

A seismic display in which each trace is drawn as a line deflecting either side of a zero axis.

wildcat

An exploration well that is drilled in an area in which little is known about the subsurface geology.

wildcat well

An exploration well drilled where no field has yet been proven.

win-win outcome

A settlement leaving both sides better off than their alternatives, and so likely to hold.

winch

A hand-powered or motor-driven lifting device designed to lift and move a load using a wire rope or chain. In wireline logging, it is used to pick up the logging tool string attached to the wireline cable.

wind turbine

A rotor converting wind into shaft power and then electricity, rated for a wind speed it rarely sees.

winder

A mechanical take-up reel that stores measuring tape; the tape is connected to a float inside a container and is released or retracted by the winder as level changes.

window

The portion of a dataset, in time or depth, over which an operator or filter is computed or applied.

wing valve

The side outlet valve on a Christmas tree through which production leaves the well.

winnowed

Winnowing is the process by which wind or water removes finer material from a coarser sediment. This process can improve the sorting of sediment.

Winsor phase behavior

The classification of oil-water-surfactant systems into Type I, II and III according to which phases the microemulsion coexists with.

wiper

The circular seat in a ball valve.

wiper plug

A rubber plug pumped ahead of and behind the cement to separate it from the mud and wipe the casing wall clean.

wiper ring

Ring scraping oil from a rod as it withdraws, keeping crankcase oil out of the process.

wiper rings

Rings located in the distance piece surrounding the piston rod that form a seal to prevent cylinder gas from passing to the crankcase and crankcase lubricant from passing to the cylinder, while also removing lubricants from the rod.

wiper trip

A short trip made to run the bit back through an interval and clean up the hole before running casing or logging.

wiping

Wiping is an additional operation when drilling a borehole that may be done to part or all of the open borehole, to ensure the borehole is the diameter and quality expected. For example, wiping (or a wiper trip) may be done when issues, such as insufficient hole cleaning, have occurred or are suspected.

wire clamp

A clamp fitted on the slickline at surface to hold it while the lubricator is broken or the stuffing box is changed.

wire connector

A cone-shaped solderless connector that has a steel spring inside it. Also called a wire nut.

wire rope

A type of rope that is made of individual wires of iron or steel that are wrapped into strands, which are then wound around a central core.

wire rope clip

A fitting that is used to clamp two sections of wire rope together.

wire-wrapped screen

A sand control screen made by winding profiled wire around a perforated base pipe at a controlled gap.

wireless network

A network using radio rather than cable, with its own exposure at the perimeter.

wireline

An electrical cable used to lower tools into and out of the wellbore and to transmit downhole condition data. Wireline relates to any aspect of logging that employs such a cable.

wireline coiled tubing

The two principal intervention conveyance methods.

wireline cutter

A tool run to cut slickline downhole so the recoverable part of the wire can be pulled and the fish left clean.

wireline formation pressure test

The wireline formation pressure measurement is acquired by inserting a probe into the borehole wall and performing a mini-drawdown and build up by withdrawing a small amount of formation fluid and then waiting for the pressure to build up to the formation pore pressure.

wireline formation test

A pressure test made by a wireline tool sealed against the borehole wall, giving formation pressure and a fluid sample.

wireline formation tester

A tool run on an electric logging cable that pushes a probe into the formation, allowing production into a small closed chamber. It is primarily used to obtain formation pressures at chosen locations, and with an accurate quartz gauge, order-of-magnitude permeability estimates may be obtained. Variations have been developed to acquire formation fluid samples.

wireline grab

A fishing tool with barbed prongs used to catch and recover broken slickline from the well.

wireline log

A record of formation properties measured continuously by a tool lowered on electric cable after the hole is drilled.

wireline logging

Wireline logging is the acquisition of geological and geophysical data as a function of the wellbore depth by lowering a string of one or more logging instruments on the end of a wireline into a borehole.

wireline logging run, wireline logging survey run

Wireline logging is the acquisition of geological and geophysical data as a function of the wellbore depth by lowering a string of one or more logging instruments on the end of a wireline into a borehole.

wireline logging tool

The instrument lowered on cable to measure formation properties.

wireline operation

Any intervention performed with tools run on cable.

wireline perforating

Perforating with guns run on electrical cable rather than on pipe.

wireline surface

The surface equipment supporting a wireline operation.

wireline tool

Any instrument run into the well on cable.

wireline tractor conveyance, tractor

A wireline tractor conveyance, or tractor, is a device for assisting a logging tool to descend a deviated or irregular profile wellbore.

wireline unit

The winch, cable and recording equipment used to run logging tools.

wireline valve

A valve set or operated by wireline, allowing intervention without killing the well.

wireline, wireline cable

Wireline relates to any aspect of logging that employs an electrical cable to lower tools into the borehole and to transmit data.

wireline-retrievable

Designed to be recovered on cable rather than requiring the tubing to be pulled.

wireline-retrievable safety valve (WRSV)

A subsurface safety valve whose working parts are run and pulled on wireline, abbreviated WRSV.

wiring diagram

A drawing or graphic representation that shows the physical locations of components, the physical relationships between them, and where electrical connections are made.

withdrawal

A partner's exit from the venture, and the obligations that survive it.

withdrawal profile

The withdrawal profile usually consists of a constant rate (plateau) period followed by a period of declining rates.

withdrawal rate

The amount of gas that can be delivered (withdrawn) from a storage facility on a daily basis.

witness testimony [evidence]

A statement about the employee's ability to perform a task can be obtained from someone who has worked closely with the employee, e.g., a line manager or supervisor. This may be useful where the Assessor is not in a position to observe an employee's performance directly. It can also be used for assessing competencies that have to be demonstrated over a period of time, such as working safely and working as part of a team.

word address

An address that refers to one or more complete 16-bit words, rather than to a single bit of a word.

word instruction

An instruction that acts on a group of bits rather than on a single bit.

word module

A type of I/O module that handles a relatively large number of input or output bits simultaneously.

wordiness and redundancy

Using more words than the meaning requires, which obscures rather than elaborates.

work

A force applied to an object times the distance that the object travels.

work A tank

To gauge and test a lease tank.

work acceptance

Formal confirmation that delivered work meets the contract before payment is released.

work basket

The elevated platform on a snubbing unit from which the operator controls the jack and handles the pipe.

work breakdown structure (WBS)

The hierarchical decomposition of the work into manageable packages.

work commitment

This term refers to Contractor's commitment to the owner of the oil and gas rights, outlining the specific work that will be guaranteed during the exploration phase. The commitment is usually made in both money amounts and the type of exploration to be undertaken (seismic surveys, exploration wells etc.). This commitment is usually divided into two or three exploration stages (about two years each) during the Exploration Period. The Work Commitment represents the minimum expenditure that a company may make during each stage - it can certainly spend more and often does. If more funds are spent in one stage, the excess normally can be credited to the next stage.

work contour

How a resource's effort is distributed across a task rather than assumed level.

work group

People grouped for coordination rather than joint output.

work of equal value

Different jobs judged comparable in demand, skill and responsibility, so warranting equal pay.

work practice controls

Controls that reduce the likelihood of exposure by altering the manner in which a task is performed (e.g., prohibiting recapping of needles by a two-handed technique).

work product [evidence]

Evaluation of work products used in conjunction with observation. Examples include a part manufactured on a machine or by hand, documents (a report, process logs, permit to work, etc.), a completed task (e.g., repaired or maintained equipment).

work station

The interactive computer system on which seismic data is processed, interpreted and displayed.

work string

A temporary tubing or pipe string run to carry out a treatment or an intervention, then pulled.

work, material and cost resources

The three resource types a plan can consume, costed differently.

work-life balance

The sustainable division between work and the rest of life.

workforce metrics

The measures — turnover, time to competence, coverage — that indicate workforce health.

workforce planning

Forecasting the number and kind of people needed, and when.

Workforce Scorecard

The framework linking workforce behavior and capability to strategic and financial results.

working capital cost

The financing cost of money tied up in inventory and receivables between paying and being paid.

working drawings

Drawings that are used in the actual construction of a building or part of a building; also referred to as blueprints and construction drawings.

working interest

The legal and revenue interest in an oil and gas lease after payment of royalties, representing the ownership interest that manages operations and pays all capital and operating costs. It is the right granted to the lessee to explore for, produce, and own oil, gas, or other minerals.

working power

Voltage and current that performs work.

workover

Major remedial work on a completed well, usually requiring the well to be killed and the tubing pulled.

workover fluid

The fluid, usually a clear brine, that holds the well dead while a workover is carried out.

workover operation

Re-entering a completed well to repair or change the completion.

workover operations

Workover operations mean the work conducted on wells after the initial well-completion operation for the purpose of maintaining or restoring the productivity of a well. Well completion/well workover means those operations following the drilling of a well that are intended to establish or restore production.

workover rig

The smaller rig used for intervention on existing wells.

workover string

The temporary string run during a workover to carry tools, circulate or convey a treatment.

workplace accessibility

Designing premises, systems and practices so disabled people can work without barriers.

workplace authenticity

Being able to work without concealing significant parts of who one is.

workplace culture

The shared norms determining how things are actually done in an organization.

workplace grievance procedure

The formal route by which an employee raises a complaint and gets a decision.

workplace hazard

Anything with the potential to cause harm at work.

workplace violence

Threats or physical harm occurring at work, from colleagues or outsiders.

workspace design

Arranging the physical working environment for comfort, focus and health.

world crude

The global crude oil market taken as a whole.

world crude oil

The global crude market and its supply and demand balance.

worldscale

The index of nominal freight rates against which tanker charters are quoted as a percentage.

worldscale flat rate

The published reference rate for a given voyage, set annually as the index base.

worm

A cylindrical gear that has teeth shaped like the threads on a screw 1.

worm gear

The gear in a motor operator that engages and is driven by the worm.

worm shaft

The shaft carrying a worm gear, giving high reduction in one stage.

wormhole

A large, highly conductive channel dissolved through carbonate rock by acid, reaching well beyond the wellbore.

wound rotor

A rotor that has conducting coils wound to match the stator windings.

wrench fault

A deep, basement-involved strike-slip fault system whose surface is essentially vertical.

wrist pin

A pin placed in a pre-positioned hole in the crank to hold the pitman arm to the crank.

wrist pin bearing

A tapered or spherical roller bearing that allows rotary motion between the crank and the pitman arm.

wti crude

West Texas Intermediate, the North American light sweet benchmark.

WTI Midland

West Texas Intermediate priced at Midland in the Permian, now part of the Brent basket.

wye connection

A connection in a three-phase AC system (also called a star connection) in which one end of each of the three phase windings is connected to a common point and the load is connected to the free ends of the coils, which connect to the three phase lines.

wye-connected stator

A stator in which the coils are connected through a common point; also called a star-connected stator.

wyllie

Author of the time-average equation relating sonic transit time to porosity.