Sunday, September 6, 2015

Drilling fluids processing glossary F

Fault. Geological term denoting a formation break across the trend of a subsurface strata. Faults can significantly affect the drilling fluid and casing programs due to possibilities for lost circulation, sloughing hole, or kicks
Feed. A mixture of solids and liquid (including dilution liquid) entering a liquid/solids separation device.
Feed capacity. The maximum volume flow rate at which a solids-control device is designed to operate without detriment to separation efficiency.This capacity will be dependent on particle size, particle concentration,viscosity, and other variables of the feed. See: capacity, flow capacity, solids discharge capacity.
Feed chamber. That part of a device that receives the mixture of diluents, drilling fluid, and solids to be separated.
Feed head. The equivalent height, in feet or meters, of a column of fluid at the cyclone feed header.
Feed header. A pipe, tube, or conduit to which two or more hydrocyclones have been connected and from which they receive their feed slurry.
Feed inlet. The opening through which the feed fluid enters a solids separation device. Also known as feed opening.
Feed mud. See: feed.
Feed opening. See: feed inlet.
Feed pressure. The actual gauge pressure measured as near as possible to, and upstream of, the feed inlet of a device.
Feed slurry. See: feed.
Fermentation. Decomposition process of certain substances, for example, starch, in which a chemical change is brought about by enzymes, bacteria, or other microorganisms. Often referred to as ‘‘souring.’’
Fibrous materials. Any tough, stringy material used to prevent loss of circulation or to restore circulation. In field use, ‘‘fiber’’ generally refers to the larger fibers of plant origin.
Filter cake. The suspended solids that are deposited on a porous medium during the process of filtration. See: wall cake.
Filter cake texture. The physical properties of a cake as measured by toughness, slickness, and brittleness. See: cake consistency.
Filter paper. Porous paper without surface sizing for filtering solids from liquids. The API filtration test specifies 9-cm-diameter filter paper Whatman No. 50, S&S No. 576, or equivalent.
Filtrate. The liquid that is forced through a porous medium during the filtration process. See: fluid loss.
Fill-up line. The line through which fluid is added to the annulus to maintain the fluid level in the well bore during the extraction of the drilling assembly.
Filter cake. (1) The soild residue deposited by a drilling fluid against a porous medium, usually filter paper, according to the standard API filtration test. (2) The soild residue deposited on the wall of a borehole during the drilling of permeable formations. See: wall cake.
Filter cake thickness. See: cake thickness.
Filter press. A device for determining the fluid loss of a drilling fluid having specifications in accordance with API RP 13B. See: API RP 13B.
Filter run. The interval between two successive backwashing operations of a filter.
Filterability. The characteristic of a clear fluid that denote both the ease of filtration and the ability to remove solids while filtering.
Filtrate loss. See: fluid loss.
Filtration. (1) The process of separation of suspended solids from liquid by forcing the liquid a porous medium while screening back the solids.Two types of fluid filtration occur in a well: dynamic filtration while circulating, and static filtration when the fluid is at rest. (2) The process of drilling fluid losing a portion of the liquid phase to the surrounding formation. See: water loss.
Filtration rate. See: fluid loss.
Fine-screen shaker. A vibrating screening device designed for screening drilling fluids through screen cloth finer than 80 mesh.
Fine-screen shale shakers. Usually refers to shale shakers that vibrate screens with a balanced elliptical or linear motion. These are usually capable of processing large flow rates of drilling fluid through 120 to 250 mesh screens.
Fine solids. Solids 44–74 microns in diameter, or sieve size 325–200 mesh. See: API RP 13C.
Fishing. Operations on the rig for the purpose of retrieving sections of pipe, collars, or other obstructive items that are in the hole and would interfere with drilling or logging operations.
Flat decked. Shaker screens that do not have a crowned, or bowed, surface.
Flat gel. A condition wherein the gel strength does not increase appreciably with time and is essentially equal to the initial gel strength. Opposite of progressive gel. See:progressive gel, zero-zero gel.
Flight. On a decanting centrifuge, one full turn of a spiral helix, such as a flute or blade of a screw-type conveyor. See: blade, flute.
Flipped. A slang term for an extreme imbalance in a drilling fluid. In a water-in-oil emulsion, the emulsion is identified as ‘‘flipped’’ when the continuous and dispersed phases separate and the solids begin to settle.
Floc. Small gelatinous masses of solids formed in a liquid.
Flocculates. A group of aggregates or particles in a suspension formed by electrostatic attraction forces between negative and positive charges. Bentonite clay particles have negatively charged surfaces that will attract positive charges such as those of other bentonite positive edge charges.
Flocculating agent. Substances, for example, most electrolytes, a few polysaccharides, certain natural or synthetic polymers, that bring about the thickening of a drilling fluid. In Bingham plastic fluids, the yield point and gel strength increase with flocculation.
Flocculation. (1) Loose association of particles in lightly bonded groups, sometimes called ‘‘flocs,’’ with nonparallel association of clay platelets. In concentrated suspensions, such as drilling fluids, flocculation results in gelation. In some drilling fluids, flocculation may be followed by irreversible precipitation of colloids and certain other substances from the fluid, such as red beds and polymer flocculation. (2) A process in which dissimilar electrical charges on clay platelets are attracted to each other. This increases the yield point and gel strength of a slurry.
Flooding. (1) The effect created when a screen, hydrocyclone, or centrifuge is fed beyond its capacity. (2) Flooding may also occur on a screen as a result of blinding.
Flowback pan. A pan or surface below a screen that causes fluid passing through one screen to flow back to the feed end of a lower screen.
Flow capacity. The rate at which a shaker can process drilling fluid and solids. This depends on rnany variables, including shaker configuration,design and motion, drilling fluid rheology, solids loading, and blinding by near-size particles. See: feed capacity.
Flow drilling. Drilling in which there is a constant flow of formation fluid.
Flowline. The pipe (usually) or trough that conveys drilling fluid from the rotary nipple to the solids-separation section of the drilling fluid tanks on a drilling rig.
Flow rate. The volume of liquid or slurry moved through a pipe in one unit of time, that is, gpm, bbl/min, etc. See: circulation rate.
Flow streams. With respect to centrifugal separators, all liquids and slurries entering and leaving a machine, such as feed drilling fluid stream plus dilution stream equals overflow stream plus underflow stream.
Fluid. Any substance that will readily assume the shape of the container in which it is placed. The term includes both liquids and gases. It is a substance in which the application of every system of stress (other than hydrostatic pressure) will produce a continuously increasing deformation without any relation between time rate of deformation at any instant and the magnitude of stress at the instant.
Fluid flow. The state of dynamics of a fluid in motion as determined by the type of fluid (e.g., Newtonian plastic, pseudoplastic, dilatant), the properties of the fluid such as viscosity and density, the geometry of the system, and the velocity. Thus, under a given set of conditions and fluid properties, the fluid flow can be described as plug flow, laminar (called also Newtonian, streamline, parallel, or viscous) flow, or turbulent flow. See: Reynolds number.
Fluid loss. Measure of the relative amount of fluid loss (filtrate) through permeable formations or membranes when the drilling fluid is subjected to a pressure differential. See: filtrate loss, API RP 13B.
Fluidity. The reciprocal of viscosity. The measure of rate with which a fluid is continuously deformed by a shearing stress. Ease of flowing.
Fluorescence. Instantaneous re-emission of light of a greater wavelength than that of the light originally absorbed.
Flute. A curved metal blade wrapped around a shaft as on a screw conveyor in a centrifuge. See: blade, flight.
Foam. (1) A two-phase system, similar to an emulsion, in which the dispersed phase is a gas or air. (2) Bubbles floating on the surface of the drilling fluid. The bubbles are usually air but can be formation gas.
Foaming agent. A substance that produces fairly stable bubbles at the air/liquid interface due to agitation, aeration, or ebullition. In air or gas drilling, foaming agents are added to turn water influx into aerated foam. This is commonly called ‘‘mist drilling.’’
Foot. Unit of length in British (foot-pound-second) system.
Foot-pound. Unit of work or of mechanical energy, which is the capacity to do work. One foot is the work performed by a force of 1 pound acting through a distance of 1 foot; or the work required to lift a 1-pound weight a vertical distance of 1 foot.
Foot valve. A check valve installed at the suction end of a suction line.
Formation. A bed or deposit composed throughout of substantially the same kind of rock.
Formation damage. Damage to the productivity of a well as a result of invasion of the formation by drilling-fluid particles, drilling-fluid filtrates, and/or cement filtrates. Formation damage can also result from changes in pH and a variety of other conditions. Asphalt from crude oil will also damage some formations. See: mudding off.
Formation fluid. The fluid—brine, oil, gas—that is in the pores of a formation.
Formation sensitivity. The tendency of certain producing formations to adversely react with the drilling and completion process.
Free liquid. The liquid film that can be removed by gravity draining or centrifugal force. See: absorb, absorption, adsorption, adsorb, bound liquid.
Free-water knockout. A water/gas separator ahead of the flare line.
Freshwater drilling fluid. A drilling fluid in which the liquid phase is freshwater.
Freshwater mud. See: freshwater drilling fluid.
Friction loss. See: pressure drop, pressure loss.
Functions of drilling fluids. Drilling fluids in rotary drilling must remove cuttings from the bottom of the hole, bring those cuttings and any material from the side of the hole to the surface, subsurface formation pressures, cool the drill bit, lubricate the drill string, create an impermeable filter cake, refrain from invading the formations with excessive quantities of drilling-fluid filtrate, and provide a well bore that can be evaluated and produce hydrocarbons.
Funnel viscosity. See: kinematic viscosity, marsh funnel viscosity.

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