Terminology Series W

Working in the Oil and Gas industrywill introduce you to a whole new set of industry-specific vocabulary and abbreviations – to help you understand we’ve collated a list of a few terms beginning with the letter "W" that focus on Drilling.

Wait On Cement (WOC)

This abbreviation refers to suspending drilling operations so cement slurries can harden and solidify. This allows the slurry to develop compressive strength so small cracks or fluid pathways do not form. The WOC time can range from a few hours up to several days and the drilling crew will usually use this time for maintenance.

Wall Sticking

Refers to a condition where the drill string cannot move along the axis of the wellbore. This is sometimes known as ‘Differential Sticking’. This is often described as the greatest drilling problem in terms of financial costs and time lost and it occurs when high-contact forces caused by low reservoir pressures, high wellbore pressures, or both, are exerted over a large area of the drillstring.

Wellbore Orientation

Wellbore Orientation describes the direction of the wellbore in terms of inclination and azimuth. Inclination is the vertical angle and Azimuth is the horizontal angle.


Refers to the borehole, drilled hole, openhole or uncased portion of the well.


The system of valves, spools and assorted adapters that provide pressure control for a production well.

Wiper Plug

A Wiper Plug, (sometimes referred to as a cementing plug) is a rubber plug used to separate the cement slurry from other fluids. This reduces contamination and maintains predictable slurry performance.

Wireline Log

Refers to the continuous measurement of formation properties. Electrically powered instruments are used to gather information about the formation so decisions can be made about drilling operations.


This term refers to the stimulation or repair of an existing production well. The purpose of this is to restore or prolong the production of hydrocarbons.


An openhole section or an enlarged region of a wellbore. A Washout is usually larger than the size of the drillbit and can be caused by excessive bit jet velocity, soft formations, in-situ rock stresses, mechanical damage amongst other reasons. They can become more severe with time but using an appropriate mud time can minimize them.

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