W

Water drive

A kind of extracting process where oil or gas are driven out of the layer due to the pressure from the underlying water.

Water flooding

Injecting water into a reservoir in order to get additional oil out of the reservoir rock and into the borehole of already producing wells. 
 

Water injection

Injecting water into the oil or gas producing layer in order to maintain or increase the pressure in the subsoil.
 

Weak point

A piece of steel cable placed inside a logging head that is designed to break for instance at a pre-determined tension. In case the logging tool becomes stuck, logging cable may break at surface as that is the place of maximum tension. Weak point is designed to break before the cable, so cable can be retrieved and leaving only the logging tool and head down hole.
 

Weather window

Often refers to a short period between two lows.
 

Weight on bit (WOB)

The amount of downward force placed on the bit, the force is applied by the weight from the drill string.
 

Wellbore damage

The relationship between the theoretical and actual production achieved through a drill stem test.
 

Wellhead

Equipment at the surface of a well for controlling the pressure of a production well. The wellhead includes all equipment on the surface that supports the various pipe strings, seals off the well and controls the paths and flow rates of reservoir fluids.

Wellhead

Well logging

A procedure where electrical gauges are lowered into the borehole in order to examine the quality of the hydrocarbon-leading layer.
Also a term describing the constant flow of data and information gathered from a well during drilling.
 

Well servicing

Performing maintenance on an oil or gas well in order to improve or resume production.
 

Wet natural gas

Natural gas that contains larger amounts of fluids.
 

Wet tree

A wellhead located below the surface.
 

Whipstock

Wedge-shaped equipment at the bottom of the drill shaft. The purpose is to get the drill bit and drill string to change direction when drilling is resumed.
 

Wildcat

Drilling a well without knowledge of the rocks structure or content.
 

Wildcat appraisal well

A drilling made close to a prior finding of oil or gas where content or structure of the rocks is unknown.
 

WOB

See weight on bit
 

Workover

A term used for operations with a purpose of restoring or increasing production when a reservoir stops producing at the rate it should. Many workover jobs involve treating the reservoir rocks rather than the down hole equipment.
 

WOW

Waiting on weather.
 

Working pressure

The pressure that equipment is constructed to normally function under.
 

WTI (West Texas Intermediate)

A kind of crude that is often used as standard of reference for pricing.

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