glossary

A drilling fluid (mud) in which water or saltwater is the major liquid phase as well as the wetting (external) phase. General categories of water-base muds are fresh water, seawater, salt water, lime, potassium and silicate.

Natural gas that contains less methane (typically less than 85% methane) and more ethane and other more complex hydrocarbons.

Oil that contains basic sediment and water.

An exploration well. The significance of this type of well to the drilling crew and well planners is that by definition, little if anything about the subsurface geology is known with certainty, especially the pressure regime.

A record of rock properties and their fluids that are measured by an instrument raised up the well on a wireline.

The repair or stimulation of an existing production well for the purpose of restoring, prolonging or enhancing the production of hydrocarbons (see oil production) The process of performing major maintenance or remedial treatments on an oil or gas well.
In many cases, workover also implies the removal and replacement of the production tubing string after the well has been killed (see killing a well) and a workover rig has been placed on location. Through-tubing workover operations, using coiled tubing, snubbing or slickline equipment, are routinely conducted to complete treatments or well service activities that avoid a full workover where the tubing is removed. This operation saves considerable time and expense.