Oil and Gas Terms Beginning with “W”

(noun) Abbreviation for Water Alternating Gas. An enhanced oil recovery technique in which slugs of water and gas (typically carbon dioxide, nitrogen, or hydrocarbon gas) are alternately injected into a reservoir to… Read more →

WOC (waiting on cement) is a period of planned inactivity at a wellsite during which drilling operations are suspended after a cement job has been pumped into the casing annulus or wellbore, allowing the cement slurry… Read more →

Abbreviation for water/oil ratio, the ratio of produced water to produced oil. Read more →

The Wadati-Benioff zone is the inclined plane of earthquake hypocenters that defines the location of a subducting oceanic lithospheric plate as it descends into the Earth's mantle beneath an overriding plate at a… Read more →

What Is a Walking System? A walking system is a self-propelled hydraulic mechanism that moves a land drilling rig short distances between wellheads on a multi-well pad without rigging down the derrick or disconnecting… Read more →

The Walsh-Hadamard transform (WHT) is a mathematical signal processing operation that decomposes a signal into a sum of Walsh functions (a complete orthonormal set of square wave basis functions that take values of plus… Read more →

Walther's Law (also spelled Walther's law or the law of the correlation of facies) is a fundamental principle of stratigraphy and sedimentary geology, formulated by the German geologist Johannes Walther in 1894, stating… Read more →

What Is a Wear Bushing? A wear bushing is a replaceable steel sleeve inserted into the rotary table bowl or spider bowl to absorb abrasion and impact from rotating drill pipe tool joints and casing connections,… Read more →

What Is a Wellbore? A wellbore is the physical hole drilled from the earth's surface into a subsurface formation, forming the fundamental conduit through which drilling fluids circulate downward and reservoir fluids… Read more →

Wide-azimuth towed streamer acquisition (WATS) is a marine seismic acquisition technique that records seismic data over a broader range of source-to-receiver azimuths than conventional narrow-azimuth towed streamer… Read more →

What Is Winsor Phase Behavior? Winsor phase behavior describes the equilibrium microemulsion and excess-phase relationships that develop when a surfactant contacts oil and water, classified by British chemist P.A.… Read more →

What Is Wire Rope? Wire rope is a multi-strand steel cable used throughout the global oil and gas industry to hoist drill string, support travelling blocks, anchor offshore platforms, and secure subsea moorings.… Read more →

Wait on cement (WOC) is the period of time after a cement job has been pumped and the wellhead or casing hanger has been set, during which drilling or completion operations are suspended to allow the cement slurry to… Read more →

Wait time in nuclear magnetic resonance (NMR) logging and laboratory NMR petrophysics is the time interval (measured in seconds) between the end of one pulse sequence (the echo train acquisition) and the beginning of… Read more →

A walk-above vertical seismic profile (also called a walkabove VSP or walk-above VSP) is a seismic acquisition geometry in which the seismic source at the surface is progressively moved to maintain a position directly… Read more →

A walkaway vertical seismic profile (walkaway VSP) is a borehole seismic acquisition technique in which geophones are fixed at one or multiple depths in a wellbore while surface seismic sources are fired at… Read more →

Wall loss in oilfield tubular and pipeline inspection refers to the reduction in the original wall thickness of a steel pipe, casing, tubing, or vessel caused by corrosion, erosion, or mechanical wear, expressed either… Read more →

What Is a Wash Out? A wash out describes an enlarged section of openhole wellbore where the actual diameter exceeds the bit size, identified by an over-gauge reading on the caliper log . Drillers control wash out risk… Read more →

A wash pipe is a relatively large internal-diameter tubular component of a fishing tool string that is used together with a burn shoe to wash over a stuck fish (drill pipe, drill collar, casing, packer, or other… Read more →

What Is a Washout? A washout is a hole or severe thin spot cut into pressure equipment by fast-moving fluid, gas, drilling mud, or sand. It starts as erosion, but it can become a pressure-control problem. API RP 14E is… Read more →

Washover in petroleum drilling and workover operations is a fishing technique used to free stuck pipe (drill pipe, drill collars, casing, or tubing) that is mechanically held in the wellbore by cement, junk, formation… Read more →

Washover pipe (also called washpipe or a washover string) is a specialized tubular run in fishing operations over a stuck or lost fish (a piece of pipe, bit, or other downhole equipment stuck in the wellbore) to wash… Read more →

Wastewater cleanup in the oil and gas industry refers to the treatment, remediation, and disposal of contaminated water streams generated during drilling, production, and processing operations — encompassing everything… Read more →

A water-base drilling fluid (WBDF, also called water-base mud or WBM) is a drilling fluid system in which water (fresh water, brackish water, saturated salt water, or seawater) serves as the major liquid phase and as… Read more →

What Is a Water Block? A water block is a type of formation damage caused by the capillary retention of water in the pore system of a gas or oil reservoir following the invasion of aqueous fluids from drilling,… Read more →

Water clarification is the process of removing suspended solids, dispersed oil droplets, emulsified hydrocarbons, and other particulate matter from produced water or water injection streams to produce a clarified… Read more →

(noun) A production phenomenon in which water from an underlying aquifer migrates upward toward the well perforations due to pressure drawdown, forming a cone-shaped intrusion of water around the wellbore that increases… Read more →

Water control in oil and gas production refers to the range of engineering techniques and treatment methods used to reduce, redirect, or shut off unwanted water production from oil and gas wells — water that dilutes the… Read more →

A water cushion is a volume of water deliberately placed in the production tubing string below the drill string or above a formation zone before conducting a drillstem test (DST) or before opening a well to initial… Read more →

What Is Water Cut in Oil and Gas? Water cut is the fraction of total liquid production that is water, expressed as a percentage. If a well produces 800 barrels of water per day (BWPD) and 200 barrels of oil per day… Read more →