An adaptive drilling process used to precisely control the annular pressure profile throughout the wellbore (iadc definition).

The initial part of the fracture fluid that creates the fracture width and controls the initial fluid loss but contains no proppant.

A displacement. in the reservoir a sweep is displacement of a hydrocarbon fluid from a reservoir rock by a flooding fluid. in the wellbore, a sweep is a viscous pill circulated around to help clear the wellbore of cuttings or debris.

A downhole device that isolates wellbore pressure and fluids in the event of an emergency or catastrophic failure of surface equipment. the control systems associated with safety valves are generally set in a fail-safe mode, such that any interruption or malfunction of the system will result in the safety valve closing to render the well safe. downhole [...]

Abbr. installation / workover control system
find more info about iwocs at hydrafit-subsea.co.uk

The amount of the pore volume of a reservoir rock that is filled by water, oil, or gas and measured in routine core analysis.

1. a scale of pressure differences in which there is a uniform variation of pressure from point to point. for example, the pressure gradient of a column of water is about 0.433 pounds per square inch per foot (9.794 kilopascals per meter) of vertical elevation. the normal pressure gradient in a formation is equivalent to [...]

See production rig. also see pulling unit.

Water that contains relatively low concentrations of soluble salts. brackish water is saltier than fresh water but not as salty as salt water.

The gradient needed to initiate a fracture.

To perform one or more of a variety of remedial operations on a producing oil well to try to increase production. examples of workover opera6tions are deepening, plugging back, pulling and resetting liners, squeeze cementing, and so on.

Abbr. health, safety and environment.

The permeability of the pack times its width. expressed in md-ft.

A volume of fluid, without proppant, injected in front of a frac job to establish frac width.

Abbr. prove undeveloped (reserves).
see also proved undeveloped reserves.