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

The volume of fluid (expressed in percent) that separates from a cementslurry when the slurry is left static. The free fluid can be measured as specified in API Recommended Practice 10B. Free fluid is also known as free… Read more →

Gas that exists in the reservoir in the gaseous phase rather than in solution. As soon as formationpressure drops below the bubblepoint, gas is evolved. This is referred to as free gas while it is in the reservoir. Read more →

The depth at which a tubing or coiled tubing string that is stuck in the wellbore is free to move. When the tubing string must be cut to enable recovery, the free point should be known to ensure retrieval of the cut… Read more →

Water in the pore space that can flow under normal reservoir conditions. When used in connection with nuclear magnetic resonance (NMR) measurements, free water is all the water that is not clay bound, capillary bound or… Read more →

In gravity surveying, a correction of 0.3086 mGal/m [0.09406 mGal/ft] added to a measurement to compensate for the change in the gravitational field with height above sea level, assuming there is only air between the… Read more →

In a nuclear magnetic resonance measurement, the decay, or relaxation, caused by dephasing in an inhomogeneous magnetic field. Since this relaxation is not related to formation properties, it is unwanted and corrected… Read more →

A wireline tool used to determine the free point on a stuck string. The free-point indicator operates by detecting stretch in the tubular when tension is applied at surface. If stretch is not detected, the string must… Read more →

A vertical or horizontal separator used mainly to remove any free water that can cause problems such as corrosion and formation of hydrates or tight emulsions, which are difficult to break.A free-water knockout is… Read more →

The rate of repetition of complete wavelengths of electrical signals, light, sound and seismic waves measured in cycles per second, or hertz, and symbolized by f. Typical recorded seismic frequencies are in the range of… Read more →

In seismic surveying or processing, the use of a function of frequency rather than time to express an independent variable or measurement. In contrast, in the time domain, variables are expressed as a function of time… Read more →

A core that is in the same state as when it was brought to the surface. A fresh core is sealed as soon as possible after retrieval from the well to minimize the loss of fluids and exposure to air. The term implies that… Read more →

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

In a gradiomanometer tool or pressure derivative calculation, the apparent increased fluid density observed due to frictional pressure losses along the tool and casing in a fast-flowing fluid. The magnitude of the… Read more →

An additive, generally in slurry or liquid form, used to reduce the friction forces experienced by tools and tubulars in the wellbore. Friction reducers are routinely used in horizontal and highly deviated wellbores… Read more →

A multiphase flow regime in near-vertical pipes in which large slugs of gas move up the center of the pipe, usually carrying small droplets of oil or water with them. Most of the remaining oil or water flows up along… Read more →

A log or a recording in which the complete signal received at an acoustic transducer is recorded. With full-waveform recording, it is possible to determine the slowness not only of the first arrival but also of later… Read more →

A description of the internal area and surfaces of a tool or tubular assembly through which there is an unimpeded internal diameter. In some cases, fullbore is used to describe the form of a nominal internal diameter… Read more →

A type of flowmeter in which the spinner blades are collapsed to pass through the tubing and other restrictions, and then opened up below to sense the full cross section of the casing or openhole. In this way, a much… Read more →

Time, in seconds for one quart of mud to flow through a Marsh funnel. This is not a true viscosity, but serves as a qualitative measure of how thick the mud sample is. The funnel viscosity is useful only for relative… Read more →