18 July 2017

Drilling spool

A connection component with ends either flanged or hubbed. It must have an internal diam at least equal to the bore of the blowout preventer and […]
18 July 2017

Drilling under pressure

Carrying on drilling operations while maintaining a seal at the top of the wellbore to prevent the well fluids from blowing out.
18 July 2017

Drilling window

(also, “drilling margin”) The drillable pressure profile, bounded on the low side by formation pressure, below which formation fluids will enter the wellbore, and on the […]
18 July 2017

Drillship

A ship constructed to permit a well to be drilled from it at an offshore location. Although not as stable as semisubmersible MODUs, drillships are capable […]
18 July 2017

Drive bushing

Device used to transmit torque from the rotary table to the kelly but allow vertical movement of the kelly while drilling. It may have pins fitting […]
18 July 2017

Drum

1) a cylinder around which wire rope is wound in the drawworks. The drawworks drum is that part of the hoist on which the drilling line […]
18 July 2017

Dry hole

Somewhat loosely used in oil work, but in general any well that does not produce oil or gas in commercial quantities. A dry hole may flow […]
18 July 2017

Dual active heave Drawworks system

Utilization of two active heave drawworks to provide full load compensation without the need of a crown-mounted compensation system and to increase the speed of the […]
25 July 2017

Dual gradient drilling

Dual gradient drilling (DGD) is a subset of MPD. As defined by the IADC, DGD means “two or more pressure gradients within selected well sections to […]
18 July 2017

Dual vertical rackers

In a parallel racking system often the design will include a second racker on the same track system. This is to facilitate redundancy as well as […]
18 July 2017

Dutchman

The portion of a stud or screw which remains in place after the head has been twisted off in an effort to remove the entire stud […]