Oil and Gas Terms Beginning with “F” — Page 8

(noun) The downhole pressure at which a formation rock fractures and a hydraulic fracture initiates and propagates. Fracturing pressure is a function of the in-situ stress state, rock tensile strength, pore pressure,… Read more →

Free fluid, sometimes called free water, is the volume of liquid that separates from a cement slurry when the slurry is left static during the period between mixing and the onset of hydration set, expressed as a… Read more →

Free gas is the natural gas phase that exists separately from liquid oil within a reservoir, formed when formation pressure drops below the bubblepoint pressure of the original undersaturated crude. Above bubblepoint… Read more →

The free point, in drilling and fishing operations, is the depth in the drill string or stuck pipe at which the string transitions from being fixed in place by sticking forces (differential sticking, key seating,… Read more →

Free water in oilfield contexts refers to water that exists as a distinct, mobile phase rather than being chemically bound to a solid surface, adsorbed onto clay minerals, trapped in capillary-bound micro-pores, or… Read more →

The free-air correction (FAC) is a correction applied to raw gravity survey measurements to remove the effect of the elevation of the measurement station above the datum (typically sea level or the geoid), based on the… Read more →

Free-induction decay (FID) is the transient signal recorded from nuclear magnetic resonance (NMR) measurements immediately after the application of a radiofrequency (RF) pulse that tips the net magnetization of hydrogen… Read more →

A free-point indicator (FPI) is a wireline-deployed downhole tool used in drilling and workover operations to locate the depth at which a stuck pipe string transitions from being mechanically constrained (stuck) to… Read more →

What Is a Free Water Knockout? Free water knockout (also called FWKO) is a vertical or horizontal pressure vessel installed as the first separation stage in a produced fluids handling train to remove the bulk of free… Read more →

What Is Frequency? Frequency measures the rate of repetition of complete wavelengths in electrical, acoustic, or seismic signals, expressed in cycles per second or hertz (Hz) and symbolized by f. Reflection seismic… Read more →

The frequency domain is a mathematical representation of a signal in which the independent variable is frequency (measured in hertz) rather than time. Any time-domain signal (such as a seismic trace showing amplitude… Read more →

A fresh core is a rock core sample that is in the same state as when it was brought to the surface from the wellbore — preserved through immediate sealing protocols that minimize the loss of fluids, exposure to… Read more →

Water that is low in dissolved salt (< 2000 ppm). Read more →

The friction effect in petroleum engineering refers to the pressure loss generated when fluids flow through pipes, annuli, perforations, fractures, and porous media due to viscous shear and turbulent energy dissipation… Read more →

A friction reducer in oil and gas operations is a chemical additive, generally supplied as a liquid emulsion or slurry, that is incorporated into hydraulic fracturing slickwater or drilling fluids to reduce the… Read more →

Froth flow is a multiphase flow regime in near-vertical pipes characterized by large slugs of gas moving upward through the center of the pipe (typically carrying small droplets of oil or water with them as entrained… Read more →

Full waveform in acoustic logging refers to the complete time-domain recording of the pressure wave train received at a detector after an acoustic pulse is transmitted from a source in the borehole — capturing not just… Read more →

Fullbore (also written as full bore or full-bore) in the context of oilfield equipment refers to a valve, fitting, or completion component that has an internal flow passage with an inside diameter equal to (or very… Read more →

A fullbore spinner is a production logging tool that measures fluid flow velocity inside a wellbore using a multi-blade impeller (spinner) that rotates at a speed proportional to the fluid velocity past the tool — the… Read more →

Funnel viscosity is a field measurement of drilling fluid thickness, defined as the number of seconds required for one US quart (946 mL) of mud to flow by gravity through a standard Marsh funnel. The Marsh funnel itself… Read more →