18 July 2017

Narrow drilling margin

A situation in which the formation pressure is very close to the fracture pressure. Often encountered in deepwater, narrow drilling windows complicate drilling operations, requiring multiple […]
18 July 2017

Narrow margin drilling practices

Narrow margin drilling practices refer to practices and procedures adopted when there is only a small margin (or window) between either: A. The lowest measured (or […]
18 July 2017

Natural gas

Highly compressible, highly expansible mixture of hydrocarbons with low specific gravity and occurring naturally in gaseous form. Besides hydrocarbon gases, natural gas may contain appreciable quantities […]
18 July 2017

Needle valve

A globe valve that incorporates a needlepoint disk to produce extremely fine regulation of flow.
18 July 2017

Negative Pressure Testing

A test in which the hydrostatic pressure is reduced such that the net differential pressure direction is from the formation into the wellbore. (Duplicate of term […]
18 July 2017

Negative Test

A test in which the hydrostatic pressure is reduced such that the net differential pressure direction is from the formation into the wellbore.
18 July 2017

Nipple

A tubular pipe fitting threaded on both ends and less than 12 inches long.
18 July 2017

Nipple chaser

A material-man whose duty it is to procure and deliver to the drilling rig the necessary tools and equipment to carry on the work.
18 July 2017

Nipple down

Disassembly of well control equipment and lines for removal.
18 July 2017

Nipple up

In drilling, to assemble the blowout preventer stack on the wellhead at the surface.
18 July 2017

Non-shearable

A non-shearable is normally accepted as a component of the drillstring: BHA or a large size casing string that cannot be sheared under expected wellbore conditions […]
18 July 2017

Normal circulation

The smooth, uninterrupted circulation of drilling fluid down the drill stem, out the bit, up the annular space between the pipe and the hole, and back […]