Oil and Gas Terms Beginning with “V”

An opening at floor level in a side of a derrick or mast, opposite the drawworks, used as an entry to bring in drill pipe, casing, and other tools from the catwalk. Read more →

The V-G meter, formally known as the direct-indicating viscometer or Fann VG meter, is the standard instrument used in drilling operations to measure the flow properties of drilling muds at surface conditions. It… Read more →

VAMA (vinyl acetate-maleic anhydride copolymer) is a synthetic organic polymer used as a filtration control additive and viscosifier in water-based drilling fluids, formed by the free-radical copolymerization of vinyl… Read more →

VAPEX (Vapor Extraction) is a thermal-free enhanced heavy oil and bitumen recovery process in which a gaseous or near-critical solvent (typically propane, butane, ethane, or a mixture of light hydrocarbons) is injected… Read more →

A VG meter, short for viscosity-gel meter, is the field name for the direct-indicating concentric-cylinder viscometer used at the rig site to measure the flow properties and gel strengths of drilling mud, and in… Read more →

Abbreviation for very large crude carrier. Read more →

What Is a Vertical Seismic Profile (VSP)? A vertical seismic profile (VSP) is a class of borehole seismic measurement in which seismic energy is generated at surface (or near surface) and detected by geophones… Read more →

VAPEX (Vapor Extraction) is a thermal-free enhanced heavy oil and bitumen recovery process in which a gaseous or near-critical solvent (typically propane, butane, ethane, or a mixture of light hydrocarbons) is injected… Read more →

Vapor pressure is the pressure exerted by a vapor in equilibrium with its corresponding liquid (or solid) phase at a given temperature, quantifying the tendency of molecules in the liquid to escape into the gaseous… Read more →

A vapor recovery unit (VRU) is a surface compression and processing system that captures hydrocarbon vapors that would otherwise be emitted to the atmosphere from crude oil storage tanks, produced water tanks, loading… Read more →

Vaporizing drive is a gas injection enhanced oil recovery (EOR) mechanism in which a dry injected gas (dry hydrocarbon gas, CO2, or nitrogen) that is initially not miscible with the reservoir oil progressively vaporizes… Read more →

Variable rate in oil and gas well operations refers to a production or injection rate that changes over time — either deliberately as part of a planned operating protocol (variable-rate testing, rate-controlled… Read more →

A variable density log (VDL) is a cement bond log presentation in which the full recorded acoustic waveform at each depth level is displayed as a continuous gray-scale or color-coded 2D image, with waveform amplitude… Read more →

Varimax rotation is an orthogonal factor rotation method in multivariate statistical analysis that rotates the coordinate axes of a principal component analysis (PCA) or factor analysis solution to achieve a "simple… Read more →

A variogram (or semivariogram) in petroleum geostatistics is a mathematical function that quantifies the spatial variability of a reservoir property — such as porosity, permeability, net-to-gross ratio, or facies… Read more →

A varve is a rhythmic sedimentary couplet deposited in annual cycles in glacial lake environments, with each varve representing one year's deposition through alternating summer and winter components — the summer layer… Read more →

A vee door (also spelled V-door) is the V-shaped opening in the side of a drilling rig's substructure and derrick at the drill floor level through which drill pipe, casing, tubing, and other tubular goods are hoisted… Read more →

A vee door (also spelled V-door) is the V-shaped opening in the side of a drilling rig's substructure and derrick at the drill floor level through which drill pipe, casing, tubing, and other tubular goods are hoisted… Read more →

What Is Velocity in Oil and Gas Geoscience? In oil and gas geoscience and well logging, velocity refers to the speed at which acoustic (elastic) waves travel through subsurface formations, expressed as compressional… Read more →

Velocity analysis, in seismic data processing, is the process of estimating the subsurface seismic wave velocity as a function of depth (or two-way travel time) from the moveout behavior of reflections on seismic… Read more →

A velocity anomaly is a distortion in seismic data caused by lateral or vertical changes in the speed at which sound travels through the rock, and it is one of the most persistent traps in subsurface interpretation.… Read more →

A velocity correction in seismic processing is any adjustment applied to recorded data so that reflectors appear at their correct two-way travel time, true depth, and accurate lateral position, compensating for the fact… Read more →

A velocity image in petroleum geophysics is a two-dimensional or three-dimensional spatial representation of seismic wave velocities throughout a subsurface volume — derived from the analysis of seismic reflection… Read more →

Velocity layering refers to the division of the subsurface into intervals of rock or sediment that share a common seismic velocity, as distinct from the geological layering or bedding defined by depositional and… Read more →

(noun) A spatial representation of seismic wave propagation velocities across a survey area at a specific depth or time horizon, derived from seismic data processing and well tie analysis. Velocity maps are used for… Read more →

A velocity string is a small-diameter production tubing string — typically 1 to 2 inches in nominal diameter — installed inside the existing production tubing of a gas well that has experienced liquid loading, designed… Read more →

A velocity survey is a set of borehole measurements that establish how fast seismic energy travels through subsurface rock as a function of depth, producing the average velocity versus depth function that geophysicists… Read more →

A velocity correction factor (VCF) is a dimensionless multiplier or correction term applied to a measured or estimated seismic, acoustic, or fluid velocity to account for systematic deviations between the conditions… Read more →

What Is a Velocity-Shot Measurement? A velocity-shot measurement is a borehole seismic technique that fires a seismic source at the surface while a geophone receiver clamped inside the wellbore records the direct… Read more →

Verification in wireline logging is the systematic set of quality control checks performed at the wellsite before, during, and after a logging run to confirm that the tool's measurements are functioning correctly, that… Read more →