Discover the IHRDC Energy Glossary_beta

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V

vacuum

A space or condition that has a pressure lower than atmospheric pressure.

vacuum breaker

A type of valve that is often installed on storage tanks to allow air into the tank to equalize pressure and prevent a vacuum developing as the tank is being drained.

vacuum column

A distillation column run below atmospheric pressure so heavy fractions boil without cracking.

vacuum condition

Pressure below atmospheric, which draws air into leaks rather than pushing product out.

vacuum distillation

Distillation at lower than atmospheric pressure; used when high temperatures would cause thermal degradation of the process material.

vacuum distillation system

The vacuum column and its ejectors, distilling heavy fractions without cracking them.

vacuum distillation unit

The tower distilling atmospheric residue under reduced pressure.

vacuum gasoil (VGO)

The heavy distillate from the vacuum tower, the usual feed to a catalytic cracker.

vacuum pump

A pump maintaining pressure below atmospheric.

vacuum system

Equipment maintaining pressure below atmospheric.

vacuum tower

A distillation tower that operates under a partial vacuum.

vacuum unit

A unit that uses reduced pressures to separate gas oils and pitch, or bottoms, from the residuum fraction.

vacuum vent

A vent that is used to admit air into a tank to prevent a vacuum from developing during loading or unloading.

vacuum vents

Vents that are used to admit air into a tank to avoid pulling a vacuum.

The vadose zone, also known as the unsaturated zone or zone of aeration, is a subsurface area between the land surface and the water table. This is an oxidating environment in which organic matter is destroyed and red ferric iron oxides develop. This region is subject to many physical, chemical, and biological processes.

valence electron

The outer electron that takes part in bonding and conduction.

valence shell

The outermost shell of an atom consisting of the valence electrons.

valences

The combining capacities of ions, which govern water chemistry and scaling.

valid and reliable data

Data that measures what it claims, and does so consistently.

validation and verification

Checking the right thing was built, and that it was built correctly.

validation data

Data held back from training and used to check a model's performance and tune it before it is applied.

Value at Risk (VaR)

A statistical estimate of the loss a book could suffer over a period at a stated confidence level.

value chain

The full sequence of activities from exploration to end sale, each stage adding cost and margin.

value creation

Generating returns above the cost of the capital employed.

value driver

The specific lever in a contract that most affects total cost or delivered value.

value for the customer

What the customer would actually pay for, which defines what counts as waste.

value leakage

Value agreed in the contract but never realized, through weak administration or unclaimed entitlements.

value of information

The amount a decision maker would be willing to pay for information prior to making a decision. A VOI analysis provides a formal assessment of the value of data acquired, based on the extent to which the data would improve expected payoffs by reducing uncertainty surrounding a decision.

Value of Work Done (VOWD)

The value of work actually performed to date, whether or not invoiced, used for accurate cost control.

value offering

What the organization proposes to give the customer, stated in the customer's terms.

value proposition canvas

A one-page tool matching what a proposed solution offers against what the user actually needs.

values-based leadership

Leading by consistent reference to stated principles, especially when it is costly.

valve

A device designed to control the flow of fluid.

valve actuator

The device moving a valve to the position the control system asks for.

valve body

The pressure-containing shell of a valve.

valve cap

The cover over a valve stem or adjustment.

valve disc

The closure member a valve seats.

valve failure

A valve losing its function, which for a control valve means the fail position matters more than the fault.

valve lineup

The proper positioning of all valves for a specific operation, ensuring that valves that should be open are open and those that should be closed are closed, according to plant procedures. Also called valve alignment or lining up the system.

valve opening

How far a valve is open.

valve operation

Operating a valve, and how it is meant to be done.

valve packing

The compressed material sealing round a valve stem.

valve position

How far a valve is open, which the positioner confirms and the controller assumes.

valve rod

The connection between the rod string and the traveling part of the pump.

valve seat

The surface the closure member presses against to shut off flow.

valve stem

The rod transmitting motion from actuator or handwheel to the valve closure member.

valve symbol

The drawing convention identifying a valve type on a diagram.

valves

Devices used to start, stop, or regulate the flow of fluids through pipes and equipments.

VAMA

Vinyl acetate maleic anhydride copolymer, used for filtration control in high-temperature and calcium-contaminated muds.

vane

A fixed or moving blade directing flow.

vane axial fan

A type of axial fan that is basically a tube axial fan with vanes added inside the housing.

vane pump

A rotary positive displacement pump that uses rigid or flexible vanes to move liquid.

vanes

The parts of a centrifugal pump's impeller that push and move the fluid being pumped, increasing its speed.

vapor

The gaseous form of a substance which is normally liquid or solid at atmospheric temperature and pressure; fluid in a gaseous state.

vapor binding

Vapor collecting in a pump or line and stopping liquid flow.

vapor bubble

A bubble of vapor in a liquid, whose formation and collapse is cavitation.

vapor density

A measurement that indicates whether a gas or a vapor is lighter than air or heavier that air.

vapor emission

Vapor released to atmosphere, which is both a loss of product and a reportable quantity.

vapor extraction (vapex)

A non-thermal heavy oil process in which injected solvent vapor dissolves into the bitumen and lets it drain under gravity, abbreviated VAPEX.

vapor extractor

A device that is often installed on equipment with oil reservoirs to remove oil vapors by maintaining a slight vacuum in the reservoir.

vapor flow

The gas-phase flow through a column or line.

vapor freeing

The process of removing toxic, flammable, or combustible vapors from a storage tank using ventilation equipment.

vapor lock

A condition that develops when hot weather causes gasoline to vaporize too quickly, thereby preventing an adequate supply of fuel to an engine.

vapor phase

The gaseous phase in a multiphase system.

vapor pressure

The pressure exerted by vapors released from a material at a given temperature when enclosed in a vapor-tight container; the partial pressure created by vapor molecules after evaporation. Also used as a measure of a liquid's volatility.

vapor recovery

Capturing vapors that would otherwise vent and returning them to process.

vapor recovery system

Equipment that is used together to return, recover, or reduce emissions.

vapor recovery unit

A small compressor package that collects tank vapors and returns them to the sales stream instead of venting them.

vapor space

The space in a storage tank that contains the vapors that have formed from the stored liquid.

vapor system

The equipment handling and recovering vapor.

vapor/liquid ratio

A comparison of the amount of vapor and the amount of liquid contained in a gasoline blend at a specified temperature and pressure.

vaporization

The change from liquid to gas, which governs separation and product volatility.

vaporization capacity

The rate at which a facility can turn liquid into gas, sizing a regasification terminal.

vaporizing

Turning from liquid to gas.

vaporizing drive

A miscible process in which lean injected gas strips intermediate components out of the reservoir oil until the displacing front becomes miscible with it.

vapour binding

The condition in which vapour or gases either blanket the tubes or block off the flow of fluid through a heat exchanger.

vapour cloud explosion

Ignition of a dispersed flammable cloud, producing blast overpressure as well as fire.

vapour lock

Vapor forming in a pump suction or line and stopping liquid flow.

vapour recovery

Collecting vapors that would otherwise vent from tanks and loading, and returning them to process.

vapour return

Returning displaced vapor from a receiving tank to the source during transfer.

vapour stream

The gas phase leaving a separation.

vapourization

The change from liquid to gas, and the heat load that change imposes.

vapourize

Turn liquid into gas by adding heat, the duty a reboiler or vaporizer performs.

Varec valve

A pressure relief device used with some separators.

variable

An unknown that can have a wide range of possible values.

variable cost

Cost that changes with the level of production.

variable frequency drive

Drive varying motor speed by changing supply frequency, matching output to demand instead of throttling.

variable orifice

An adjustable restriction fitted ahead of a pilot or instrument to set how quickly it responds to a change.

variable rate

A test condition in which the flow rate changes appreciably during the flow period.

variable refrigerant cycle heat pump

A refrigeration system in which air temperature is controlled by the way in which refrigerant flow is directed through the system.

variable speed controller

The controller varying a driven machine's speed to match demand.

variable speed drive

A drive changing motor speed to match output to demand rather than throttling.

variable volume

A working volume that can be changed, used to adjust compressor capacity without changing speed.

variable-density log

A grey-scale or color display of the full acoustic waveform against depth, abbreviated VDL.

variable-speed coupling

A device that allows the speed of a pump to vary while the speed of its driver remains constant.

variance

Variance refers to a statistical measurement of the spread between numbers in a data set. More specifically, variance measures how far each number in the set is from the mean and thus from every other number in the data set.

variance analysis

Comparing actual cost and progress against baseline and explaining the difference.

variation and amendment

A change to scope, price or terms, and the formal instrument recording it.

varimax rotation

A rotation of factor axes that maximizes the variance of the loadings while keeping the axes orthogonal.

variogram

A plot of the average squared difference between sample pairs against the distance separating them.

varve

A pair of laminae — one coarse, one fine — deposited in a single year in a still-water lake.

vault

A free-standing concrete containment area for a storage tank.

vee-door

The inverted V opening in one side of the derrick through which pipe and tools are dragged up the ramp to the floor.

velocity

Speed and direction of movement over a period of time, determined by dividing the distance traveled by the travel time. Expressed in units such as feet per minute (FPM) or revolutions per minute (RPM).

velocity analysis

The determination of stacking or migration velocities from moveout across common midpoint gathers.

velocity anomaly

A lateral or vertical velocity change that distorts the seismic image beneath it.

velocity change

A change in seismic velocity, which bends rays and distorts depth conversion.

velocity correction

An adjustment applied to seismic data to place reflectors at their proper time or depth.

velocity correction factor

The factor converting a spinner's centerline velocity reading into the average velocity across the pipe.

velocity estimation

Projecting future capacity from observed velocity.

velocity field

Velocity as it varies through space, the thing depth conversion needs and rarely has.

velocity function

Velocity expressed as a function of depth or time rather than as a single value.

velocity image

A color or grey-scale display of measured velocity against depth and position around the borehole.

velocity layering

The division of the subsurface into layers of common velocity, which need not coincide with the bedding.

velocity map

A contour map of stacking or interval velocity across a survey area, used for depth conversion.

velocity measurement

Determining seismic velocity, from wells, from the data, or from both.

velocity model

The velocity field used to migrate and depth-convert data, and the largest single source of depth error.

velocity pressure

The pressure that is developed by the movement of air through a fan system.

velocity reduction

Slowing a stream so entrained liquid or solids can settle out.

velocity shot measurement

A radioactive tracer technique that times a tracer ejection between two detectors to give fluid velocity.

velocity string

A small-diameter string run inside the tubing to raise gas velocity above the critical rate needed to lift liquid.

velocity survey

A borehole measurement of traveltime against depth, from a check-shot survey, VSP or sonic log.

vent

A valve or passage that is used to remove air or gases from a heat exchanger.

vent line

The line releasing gas or vapor to a safe place.

vent plug

A pipe plug with a small integral valve, so pressure can be bled off before the plug itself is removed.

vent valve

A valve that allows the escape or venting of gas, air, or NGLs to depressure a cylinder, compressor package, or other equipment.

ventilating

Moving air through a space to dilute or remove contaminant.

ventilation system

A system that performs the air movement and ventilation functions in a heating, ventilation, and air conditioning system.

venture assets

Assets held through a joint venture rather than wholly owned.

venture funding

The capital raised to start and grow a business, and the terms attached.

venture structure

How ownership, control and returns are arranged among founders and investors.

Venturi

The type of restriction inside an injection torch that increases the velocity of oxygen so that it can draw acetylene into its stream.

Venturi effect

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe.

venturi valve

A valve or fitting with a converging-diverging throat, so flow accelerates through the restriction and recovers most of its pressure after it.

verbal and nonverbal communication

What is said and everything conveyed alongside it.

verification

A check that a measurement or piece of equipment is performing to specification before it is relied on.

verification listing

A printed or displayed summary of what a digital record contains — curves, depth range, parameters and formats.

vernier

A secondary scale allowing a reading to be interpolated finer than the main divisions.

vernier caliper

A slide caliper with two scales: a maîn scale and a Vernier scale. Able to take measurements accurate to the nearest thousandth.

vernier micrometer

A micrometer that permits accurate measurements to within .0001 inch, or .002 mm.

versenate

The EDTA solution used to titrate calcium and magnesium, so that water or mud hardness can be determined.

vertebra

One of the interlocking bones that make up the spinal column.

vertebrae

The stack of bones that make up the spine. Viewed from the side, the spine creates an S-curve.

vertical component

The up-down part of ground motion, which a conventional geophone records.

vertical depth

Depth measured vertically rather than along a deviated hole, and the only depth pressure responds to.

vertical displacement efficiency

The fraction of the pay thickness swept by the injected fluid.

vertical exaggeration

Stretching the vertical scale of a section, which makes gentle structure visible and steep structure misleading.

vertical flow

Flow up or down through the reservoir or the wellbore.

vertical fracture

A fracture standing vertically, which is what forms where the least stress is horizontal.

vertical lift

The vertical distance between two points in a deviated or horizontal well, as distinct from the distance along the hole.

vertical misalignment

Shaft axes offset in the vertical plane.

vertical permeability

The permeability perpendicular to the bedding plane.

vertical resistivity

Formation resistivity measured with current flowing perpendicular to the bedding, symbol Rv.

vertical resolution

The smallest vertical separation at which two features can still be told apart.

vertical response

How a measurement responds as a function of distance along the borehole axis.

vertical seismic profile (VSP)

Vertical seismic profiles (VSP) are borehole seismic measurements used for correlation with surface seismic data, for obtaining images of higher resolution than surface seismic images and for looking ahead of the drill bit.

vertical seismic profiling

Recording in the borehole from a surface source, tying seismic time to measured depth.

vertical sensitivity

An indication of how much an oscilloscope's vertical amplifier can amplify a weak signal. Vertical sensitivity is usually given in millivolts (my) per division. The smallest voltage that a general purpose oscilloscope can detect is typically about 1 mV per vertical screen division.

vertical separation

The vertical distance between two features or two fault cut-offs.

vertical separator

A separator whose vessel axis stands upright, so gas rises counter to the falling liquid.

vertical severance

Splitting mineral ownership by area, so different parties hold the rights beneath defined parts of a tract.

vertical stress

Stress from the weight of overburden, the reference the horizontal stresses are compared to.

vertical sweep efficiency

The fraction of the pay thickness actually contacted by the injected fluid.

vertical transverse isotropy (VTI)

Transverse isotropy whose symmetry axis is vertical, the usual result of horizontal layering, abbreviated VTI.

vertical vessel

A vessel standing upright, chosen where floor space is short or liquid holdup should be small.

vertical vs. horizontal integration

Owning more of the chain against expanding at the same stage of it.

vertically mounted pump

A pump installed with its shaft vertical, saving floor space and simplifying suction.

very large crude carrier

A crude tanker of roughly 200,000 to 320,000 deadweight tons, abbreviated VLCC.

vesicle

A bubble-shaped cavity left in volcanic rock by gas coming out of the magma as it cooled.

vesicular

Containing vesicles — full of gas bubble cavities, as in a scoria or vesicular basalt.

vesicular porosity

Porosity from gas bubbles frozen into a volcanic rock as it solidified.

VG meter

Direct-indicating viscometer: the rotational instrument used to measure the viscosity and gel strength of drilling mud at standard speeds.

vibration

The periodic or oscillatory motion of a physical body in alternately opposite directions. Localized vibration of the hand, wrists, and arms can occur from powered hand tools, while whole body vibration from heavy-duty vehicles or machinery can lead to problems such as back trouble.

vibration meter

A device used to measure the amount of vibration in plant equipment.

vibrator

A truck-mounted seismic source that presses a baseplate to the ground and shakes it through a controlled frequency sweep.

vibratory seismic data

Data from a vibrator source, which sweeps through a frequency range rather than releasing its energy at once.

vibroseis

The land seismic source that vibrates a controlled sweep into the ground instead of using explosives.

video conference

A meeting held over video, with its own etiquette and fatigue.

vinculum

A horizontal line placed above a term or terms in a Boolean expression to indicate the presence of a NOT function. (Plural is vincula.)

vinyl acetate-maleic anhydride copolymer

A copolymer of vinyl acetate and maleic anhydride used as a fluid-loss additive in water-base mud, abbreviated VAMA.

vinyl polymer

A polymer built from ethylene-derived monomers in which hydrogens have been replaced by other groups.

virgin formation, virgin rock formation, virgin reservoir

The subsurface rock in its natural state, before any invasion of fluids and solids from the drilling process.

virgin naphtha

Naphtha taken straight from crude distillation, before any conversion or treating.

virgin pressure

The reservoir pressure before any production has taken place.

virgin zone

The part of the formation that mud filtrate has not reached, holding its original fluids.

virtual collaboration

Working together through digital tools rather than in the same room.

virtual ground

An apparent ground. The summing junction appears to be electrically grounded whenever the reference junction is grounded, since the summing junction drives to equal the reference junction.

virtual meeting

A meeting held by video or audio, requiring more deliberate facilitation than one in person.

virtual mentored learning (VML)

VML programs combine the advantages of e-Learning with engaging learning simulation games and the support of experienced virtual mentors to drive greater retention of key skills. These programs allow individuals or teams to learn at their own pace, from home or office, on a regular schedule.

virtual private network (VPN)

An encrypted connection giving secure access to a private network over the internet.

virtual team

A team working across locations and time zones, where trust must be built without proximity.

virtualization

Running multiple logical machines on shared physical hardware.

vis

Abbreviation for viscosity, used in mud reports and cuttings descriptions.

viscometer

The instrument measuring a drilling fluid's viscosity and gel properties.

viscosified

Thickened deliberately by adding polymer or gel.

viscosifiers

A viscosifer is an additive that is used to increase the viscosity or the drilling mud.

viscosity

A property of fluids and slurries indicating their resistance to flow, defined as the ratio of shear stress to shear rate. A measure of a fluid's resistance to gradual deformation by shear stress or tensile stress. The thicker the liquid, the higher its viscosity.

viscosity and gel-strength test

The viscometer measurement giving plastic viscosity, yield point and the ten-second and ten-minute gel strengths of a mud.

viscous

Resistant to flow, a property that largely determines how readily oil can be produced.

viscous crude oil

Crude oil's viscosity can vary from a low viscosity liquid to up to tar-like, nearly solid form. Classification according to the API degree: ... Medium crude oil: API gravity from 31.1 °API to 22.3 °API (870 to 920 kg/m3) Heavy crude oil: API gravity from 22.3 °API to 10 °API (920 to 1000 kg/m3).

viscous fingering

The breakthrough of a less viscous displacing fluid in narrow branching fingers through a more viscous fluid.

viscous force

The force resisting flow that arises from a fluid's internal friction, proportional to velocity.

viscous oil

Crude of high viscosity, conventionally above about 10 cp, and correspondingly high density.

vise

A bench clamp holding work while it is machined or cut.

visible position indicator

A rod on a gate valve that rises and falls with the gate, showing from outside whether the valve is open.

visible sponsorship

Senior leaders being seen to back a change personally, without which it stalls.

vision statement

What the organization intends to become, stated to set direction.

visionary leadership

Leading by articulating a compelling future and enlisting others in it.

visual aid

Anything shown to support the message, which should carry meaning rather than decorate.

visual inspection

Examination by eye, the first and cheapest check.

visualization

Mentally rehearsing a successful delivery as preparation.

vitrinite

The maceral group derived from woody plant tissue, uniform enough in composition to serve as a maturity standard.

vitrinite reflectance

The percentage of light reflected from polished vitrinite, which rises irreversibly with thermal exposure, symbol Ro.

VLCC

Very large crude carrier: a tanker of roughly 200,000 to 320,000 deadweight tonnes, the standard vessel for long-haul crude.

VLSFO (Very Low Sulphur Fuel Oil)

Marine fuel oil meeting the 0.5 percent sulfur cap introduced in 2020.

void space

The volume within a rock not occupied by solid.

volatile organic compounds (VOCs)

Substances, such as benzene and butadiene, that can escape from equipment such as valves and pumps.

volatility

The tendency of a liquid to vaporize or evaporate; a reference to how easily a liquid can change into a vapor. The higher a liquid's volatility, the more easily it becomes a vapor.

volcanic

Pertaining to volcanoes and to the rocks and processes associated with them.

volcanic arc

The chain of volcanoes above a subduction zone.

volcanism

Volcanic activity, which supplies heat, ash beds and sometimes fractured reservoirs.

volcano

A vent in the Earth's surface through which magma, ash and gas erupt, and the landform built around it.

volt

The unit by which voltage is measured. One volt is defined as the voltage necessary to drive a current of one ampere through a resistance of one ohm, or the voltage across a conductor when one ampere dissipates one watt of power. A small letter v or a capital V is typically used as an abbreviation.