Jargon Buster

A well drilled as part of an appraisal drilling programme to better understand and estimate the physical extent, reserves and likely production rate of a field.

A well that is drilled in or next to a proven part of a pool to optimise petroleum production. Development wells are drilled after hydrocarbons have been discovered by successful exploration.

A well drilled at an angle from the vertical by using a slanted drilling rig or by deflecting the drill bit; directional wells are used to drill multiple wells from a common drilling pad or to reach a subsurface location beneath land where drilling cannot be done.

The first oil or gas well drilled in a new field.

A well in an area where petroleum has not been previously found or one targeted for formations above or below known reservoirs. Drilling carried out to determine whether hydrocarbons are present in a particular area or structure. Sometimes known as a ‘wildcat well’, particularly in areas where little drilling has taken place previously.

A high-angle well (with an inclination of generally greater than 85°) drilled to enhance reservoir performance by placing a long Wellbore section within the reservoir.

A well that has not produced oil or natural gas in 12 months.

An injection well is used to place fluid underground into porous geologic formations. This could be steam, carbon dioxide, water or other substances to help maintain reservoir pressure, heat the oil or lower its viscosity, allowing it to flow to a producing well nearby.

A well that is not currently producing oil or gas but has been safely secured and may produce in the future.

Sources: Dictionary of Oil, Gas, and Petrochemical Processing; Glossary of Oil & Gas Terms and Definitions by CAPP; Glossary of Terms by the Oil and Gas Authority