Drilling fluids processing glossary M

Main shaker. The shale shaker that processes drilling fluid from the flowline through the finest-mesh screen.
Manifold. (1) A length of pipe with multiple connections for collecting or distributing fluid. (2) A piping arrangement through which liquids, solids, or slurries from one or more sources can be fed to or discharged from a solids-separation device.
Market grade cloth. A group of industrial wire cloth specifications selected for general-purpose work, made of high-strength, square mesh cloth in several types of metals. The common metal for oilfield use is 304 or 316 stainless steel. The wire diameters are marginally larger than mill grade cloth, resulting in a lower percentage of open area. Market grade and mill grade cloths are used mostly as support screens for fine-mesh screens. See: mill grade cloth, tensile bolting cloth, ultrafine wire cloth, support screen, and calendered.
Marsh funnel. An instrument used in determining the Marsh funnel viscosity. The Marsh funnel is a container with a fixed orifice at the bottom so that when filled with 1500 cc freshwater, 1 qt (946 ml) will flow out in 26±0.5 sec. For 1000 cc out, the efflux time for water is 27.5 ±sec. It is used for comparison values only and not to diagnose drilling fluid problems. See: API Bulletin RP 13B, funnel viscosity,
Marsh funnel viscosity, kinematic viscosity.
Marsh funnel viscosity. Commonly called funnel viscosity. The Marsh funnel viscosity is reported as the time, in seconds, required for 1 qt of fluid to flow through an API standardized funnel. In some areas, the efflux quantity is 1000 cc. See: API RP 13B, funnel viscosity, kinematic viscosity, Marsh funnel.
Martin’s radii. The distance from the centroid of an object to its outer boundary. The direction of this measurement is specified by the azimuth orientation of the line (the radii in the 0°, 90°, 180°, 270°angle from horizontal).
Mass. The inertial resistance of a body to acceleration, considered in classical physics, to a conserved quantity independent of speed. The weight of a body is the product of the mass of the body and the acceleration of gravity for the specific location. In space the mass would stay constant but the weight would disappear as the gravitational acceleration approaches zero.
MBT. Methylene blue test. See: methylene blue test.
Mechanical agitator. A device used to mix, blend, or stir fluids by means of a rotating impeller blade. See: agitator, mechanical stirrer.
Mechanical stirrer. See: agitator, mechanical agitator.
Median cut. The median cut is the particle size that reports 50% of the weight to the overflow 50% of the weight to the underflow. Frequently identified as the D50 point. See: cut point.
Medium (solids). Particles whose diameter is between 74 and 250 microns.
Membrane nitrogen. Air from which water and oxygen have been removed by a filter (membrane) system.
Meniscus. The curved upper surface of a liquid column, concave when the containing walls are wetted by the liquid and convex when they are not wetted.
Mesh. (1) The number of openings (and fraction thereof) per linear inch in a screen, counted in both directions from the center of a wire. (2) An indication of the weave of a woven material, screen or sieve. A 200 mesh sieve has 200 openings per linear inch. A 200 mesh screen with a wire diameter of 0.0021 inch (0.0533 mm) has an opening of 0.0029 in. (0.074) mm and will pass a spherical particle of 74 microns diameter. See: micron.
Mesh count. Such as 30X30, or often 30 mesh, indicating the number of openings per linear inch of screen; and a square mesh. A designation of 70X30 mesh indicates rectangular mesh with 70 openings per inch in one direction and 30 openings per inch in a perpendicular direction.
Mesh equivalent. As used in oilfield drilling applications, the U.S. Sieve number that has the same-size opening as the minimum opening of the screen in use.
Methylene blue test. A test that serves to indicate the amount of active clay in a fluid system, clay sample, or shale sample. Methylene blue is titrated into a slurry until all of the negative charge sites are covered with the methylene blue. This indicates the number of active charge sites present in the slurry. See: base exchange, methylene blue titration,
MBT, cation exchange capacity, CEC.
Methylene blue titration. Methylene blue is a cation that seeks all negative charges on a clay surface after the surface has been properly prepared (see API RP13B). By titrating with a known concentration, this test provides an indication of the amount of clay present in the drilling fluid. See: methylene blue test, MBT, cation exchange capacity, CEC.
Mf. The methyl orange alkalinity of the filtrate, reported as the number of milliliters of 0.02 normal sulfuric acid required per milliliter of filtrate to decrease the pH to reach the methyl orange endpoint (pH 4.3).
Mica. Naturally occurring mineral flake material of various sizes used in controlling lost circulation. An alkali aluminum silicate.
Micelles. Organic and inorganic molecular aggregates occurring in colloidal solutions. chains of individual structural units chemically joined to one another and deposited side by side to form bundles. When bentonite hydrates, certain sodium, or other metallic ions go into solution, the clay particle plus its complement of ions is technically known as a micelle.
Micron. A unit of length equal to one-thousandth of a millimeter. Used to specify particle sizes in drilling fluids and solids control discussions (25,400 microns¼1 inch).
Mil. A unit of length equal to 1/1000 inch.
Milk emulsion. See: oil-in-water emulsion drilling fluid.
Mill grade cloth. A group of industrial wire cloth specifications with lighter wire than market grade cloth. The standard wire diameter of the grade produces a median percentage of open area. Market grade and mill grade cloths are used mostly as support screens for fine-mesh screens. See: market grade cloth, tensile bolting cloth, ultra-fine wire cloth, support screen, and calendered.
Millidarcy. 1/1000 darcy. See: darcy.
Milliliter. A metric system unit for the measurement of volume. Literally 1/1000th of a liter. In drilling-fluid analyses, this term is used interchangeably with cubic centimeter (cc). One quart is equal to approximately 946 ml.
Mini still. An instrument used to distill oil, water, and any other volatile material in a drilling fluid to determine oil, water, and total solids contents as volume percentage. See: distillation, mud still.
Mist drilling. A method of rotary drilling whereby water and/or oil is dispersed in air and/or gas as the drilling fluid. See: foam. ml. See: milliliter.
Molecule. Atoms combine to form molecules. For elements or compounds, a molecule is the smallest unit that chemically still retains the properties of the substance in mass.
Monovalent. See: valence.
Montmorillonite. A clay mineral commonly used as an additive to drilling muds. Sodium montmorillonite is the main constituent of bentonite. Each platelet of the crystalline structure of montmorillonite has two layers of silicon tetrahedra attached to a center layer of alumina octhahedra. The platelets are thin and have a broad surface. Exchangeable cations are located on the clay surfaces between the platelets. Calcium montmorillonite is the main constituent in low-yield clays. See: gel,
bentonite.
Mud. See: drilling fluid, which is the preferred term.
Mud analysis. See: drilling fluid analysis, API RP 13B.
Mud balance. A beam-type balance used in determining drilling-fluid density (mud weight). It consists primarily of a base, a graduated beam with constant volume cup, lid, rider, knife-edge, and counterweight. See: API RP 13B.
Mud box. See: back tank, possum belly.
Mud cleaner. A device that places a screen in series with the underflow of hydrocyclones. The hydrocyclone overflow returns to the mud system, and the underflow reports to a vibrating screen. Solids discharged from the screen are discarded and the screen throughput returns to the system.
Mud compartment. A subdivision of the removal, additions, or check/ suction sections of a surface system. See: mud pits, mud tanks.
Mud ditch. A trough built along the upper edge of many surface systems that is used to direct flow to selected compartments of the surface system. See: mud pits, mud compartment.
Mud engineer. See: drilling fluid engineer.
Mud gun. A submerged nozzle used to stir the drilling fluid with a highvelocity stream. See gunning the pits.
Mud hopper. See: hopper.
Mud house. A structure at the rig to store and shelter sacks of materials used in drilling fluids.
Mud inhibitor. Additives such as salt, lime, lignosulfonate, and calcium sulfate that prevent clay dispersion.
Mud logging. A process that helps determine the presence or absence of oil or gas in the various formations penetrated by the drill bit, and assists with a variety of indicators that assist drilling operations. Drilling fluid and cuttings are continuously tested on their return to the surface, and the results of these tests are correlated with the drilling depth for depth of origin.
Mud mixing devices. The most common device for adding solids to the drilling fluid is by means of the jet hopper. Some other devices to assist mixing are eductors, mechanical agitators, paddle mixers, electric stirrers, mud guns, chemical barrels, etc.
Mud pit. See: mud compartments, mud tanks.
Mud pump. Pumps at the rig used to circulate drilling fluids.
Mud scales. See: mud balance.
Mud still. See: distillation, mini still.
Mud tanks. (1) Drilling-fluid system compartments constructed of metal and mounted so they can be moved from location to location, either as a part of the rig (such as on a semisubmersible rig) or separately on unitized skids (as on most land rigs). (2) Earthen or steel storage facilities for the surface system. Mud pits are of two types: circulating and reserve. Drilling-fluid testing and conditioning is normally done in the circulating pit system.
Mud weight. A measurement of density of a slurry usually reported in lb/gal, lb/cu ft, psi/1000 ft or specific gravity. See: density.
Mud/gas separator. A vessel into which the choke line discharges when a ‘‘kick’’ is being taken. Gas is separated in the vessel as the drilling fluid flows over baffle plates. The gas flows through a line to a flare. The liquid mud discharges into the shale shaker back tank. See: gas buster, poor boy degasser.
Mudding off. A condition promoting reduced production caused by the penetrating, sealing or plastering effect of a drilling fluid. See: formation damage.
Mudding up. Process of mixing drilling fluid additives to a simple, native clay water slurry to achieve some properties not possible with the previous fluid.
MW. Abbreviation for mud weight. See: density, mud weight.

Drilling fluids processing glossary K

Kelly. A heavy square or hexagonal pipe that passes through rollers in a bushing on the drill floor to transmit rotational torque to the drill string.
Key seat. A section of a hole, usually of abnormal deviation and relatively soft formation, that has been eroded or worn by drill pipe to a size smaller than the tool joints or collars of the drill string. This keyhole-type configuration resists passage of the shoulders of these pipe upset (box) configurations when pulling out of the hole.
Kick. Situation caused when the annular hydrostatic pressure in a drilling well temporarily (and usually relatively suddenly) becomes less than the formation, or pore, pressure in a permeable downhole section. A kick occurs before control of the fluid intrusion is totally lost. A blowout is an uncontrolled influx of formation fluid into the well bore. See: blowout, kill fluid.
Kill fluid. A fluid built with a specific density aimed at controlling a kick or blowout. See: galena.
Kill line. A line connected to the annulus below the blowout preventers for the purpose of pumping into the annulus while the preventers are closed.
Killing a well. (1) Bringing a well kick under control. (2) The procedure of circulating a fluid into a well to overbalance formation fluid pressure after the bottom-hole pressure has been less than formation fluid pressure. See: kick, blowout, kill fluid.
Kilowatt-hour. Horsepower-hour (hp-hr) and kilowatt-hour (kW-hr) are
units of work.
1 hp-hr =1,980,000 ft-lb = 2545 Btu
1 hp-hr =0.7457 kW-hr
1 kW-hour = 1.341 hp-hr= 3413 Btu = 2,655,000 ft-lb:
Kinematic viscosity. The kinematic viscosity of a fluid is the ratio of the viscosity (e.g., cP in g/cm-sec) to the density (e.g., g/cc) using consistent units. In several common commercial viscometers, the kinematic viscosity is measured in terms of the time of efflux, in seconds, of a fixed volume of liquid through a standard capillary tube or orifice. See: marsh funnel viscosity.
In laminar flow, the fluid moves in plates or sections with a differential velocity across the front of the flow profile that varies from zero at the wall to a maximum toward the center for flow. These fluid elements flow along fixed stream lines that are parallel to the walls of the channel of flow. Laminar flow is the first stage of flow in a Newtonian fluid. It is the second stage of flow in a Bingham plastic fluid. This type of motion is also called parallel, streamline, or viscous flow. See: plug flow, parallel flow, turbulent flow.

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.

Drilling fluids processing glossary D

Darcy. A unit of permeability. A porous medium has a permeability of 1 darcy when a pressure of 1 atm on a sample 1 cm long and 1 sq cm in cross section will force a liquid of 1 cP viscosity through the sample at the rate of 1 cc per sec. See: millidarcy, permeability.
Decanter. See: decanting centrifuge.
Decanting centrifuge. A centrifuge that removes solids from the feed slurry and discharges them as damp underflow. Ultra-fine colloidal solids are discharged with the liquid overflow. The decanting centrifuge has an internal auger that moves the solids that have been settled to the bowl walls, out of a pool of liquid, and to the underflow. See: centrifuge.
Deck. The screening surface in a shale shaker basket.
De-duster. A tank at the end of the blooie line in air or gas drilling in which water is injected to settle the dust caused by drilling.
Deflocculant. Chemical that promotes deflocculation. See: thinner.
Deflocculation. (1) The process of thinning the drilling fluid by bonding with (neutralizing or covering) the positive electrical charges of drillingfluid additives to prevent one particle of drilling fluid from being attracted to another particle. (2) Breakup of flocs of gel structures by use of a thinner.
Defoamer. Any substance used to reduce or eliminate foam by reducing the surface tension of a liquid. See: antifoam. degasser. A device that removes entrained gas from a drilling fluid, especially the very small bubbles that do not float readily in viscous drilling fluid.
Dehydration. Removal of free or combined water from a compound.
Deliquescence. The liquification of a solid substance due to the solution of the solid by absorption of moisture from the air, for example, calcium chloride deliquesces in humid air.
Density. Mass per unit volume expressed in pounds per gallon (ppg), grams per cubic (g/cc), or pounds per cubic ft (lb/cu.ft). Drilling-fluid density is commonly referred to as mud weight.
Desand. To remove most API sand (>74 microns) from drilling fluid.
Desander. A hydrocyclone with an inside diameter of 6 inches or larger that can remove a very high proportion of solids larger than 74 micrometers.Generally,
desanders are used on unweighted muds. See: cyclone, hydrocyclone, hydroclone, desilter.
Desilt. To remove most silt particles greater than 15–20 microns from an unweighted fluid. The desilter is not normally not used on weighted drilling fluids because it can remove large amounts of barite.
Desilter. A hydrocyclone with an inside diameter less than 6 inches. It can remove a large fraction of solids larger than 15–20 microns.See: cyclone, hydrocyclone, hydroclone, desander.
Destabliziation. A condition in which colloidal particles no longer remain separate and discrete, but contact and agglomerate with other particles.
Diatomaceous earth. A very porous natural earth compound composed of siliceous skeletons. Sometimes used for controlling lost circulation and seepage losses and as an additive to cement.
Diesel oil plug. See: gunk plug.
Differential angle deck. A screen deck in which successive screening surfaces of the same deck are at different angles.
Differential pressure. The difference in pressure between two points. It is usually the difference in pressure at a given point in the well bore between the hydrostatic pressure of the drilling-fluid column and the formation pressure. Differential pressure can be positive, zero, or negative with respect to the formation pressure. See: backpressure.
Differential pressure sticking. Sticking that occurs when a portion of the drill string (usually the drill collars) becomes embedded in the filter cake resulting in a nonuniform distribution of pressure around the circumference of the pipe. The conditions essential for sticking require a permeable formation and a positive pressure (from well bore to formation) differential across a drill string embedded in a poor filter cake. See: stuck.
Diffusion. The spreading, scattering, or mixing of material (gas, liquid, or solid).
Dilatant fluid. Opposite of shear thinning. A dilatant or inverted plastic fluid is usually made up of a high concentration of welldispersed solids that exhibit a nonlinear consistency curve passing through the origin. The apparent viscosity increases instantaneously with increasing shear rate. The yield point, as determined by conventional calculations from the direct-indicating viscometer readings, is negative. See: apparent viscosity, viscosity, Bingham model, plastic viscosity, yield point, gel strength.
Diluent. Liquid added to dilute or thin a solution or suspension.
Dilution. (1) Decreasing the percentage of drilled-solids concentration by addition of liquid phase. (2) Increasing the liquid content of a drilling fluid by addition of water or oil. Dilution fluid may be a clean drilling fluid or the liquid phase of a drilling fluid.
Dilution factor. The ratio of the actual volume of drilling fluid required to drill a specified interval of footage using a solids-removal system versus a calculated volume of drilling fluid required to maintain the same drilled-solids fraction over the same specified interval of footage with no drilled-solids removal.
Dilution rate. The rate, in gpm or bbl/hr, at which fluids and/or premix is added to the circulating system for the purpose of solids management.
Dilution ratio. Ratio of volume of dilution liquid to the volume of raw drilling fluid in the feed prior to entering a liquid/solids separator.
Dilution water. Water used for dilution of water-based drilling fluid.
Direct-indicating viscometer. Commonlycalleda‘‘V-Gmeter.’’The directindicating viscometer shears fluid between a rotating outer cylinder and a stationary cylindrical bob in the center of the rotating cylinder. The bob is constrained from rotating by a spring. The spring reads the drag force on the bob, which is related to the shear stress. The rotational speed of the outer cylinder and the spacing between the bob and the cylinder the shear rate. Viscosity is the ratio of shear stress to shear rate, so this instrument may be used to determine viscosity of a fluid at a variety of shear rates. Gel strengths may also be determined after a quiescent period of a drilling fluid between the bob and the cylinder. See: API RP 13B.
Discharge. Material removed from a system. See: effluent.
Discharge spout. Extension at the discharge area of a screen. It may be vibrating or stationary. Also called discharge lip.
Dispersant. (1) Any chemical that promotes the subdivision of a material phase. (2) Any chemical that promotes dispersion of particles in a fluid. Frequently, a deflocculant is inaccurately called a dispersant. Caustic soda is a dispersant but not a deflocculant.
Disperse. To separate into component parts. Bentonite disperses by hydration into many smaller pieces.
Dispersed phase. The scattered phase (solid, liquid, or gas) of a dispersion. The particles are finely divided and completely surrounded by the continuous phase.
Dispersion. (1) Process of breaking up, scattering (as in reducing particle size), and causing to spread apart. (2) Subdivision of aggregates.Dispersion increases the specific surface of the particle, which results in an increase in viscosity and gel strength.
Dispersoid. A colloid or finely divided substance.
Disassociation. The splitting of a compound or element into two or more simple molecules, atoms, or ions. Applied usually to the effect of the action of heat or solvents upon dissolved substances. The reaction is reversible and not as permanent as decomposition; that is, when the solvent is removed, the ions recombine.
Distillation. Process of first vaporizing a liquid and then condensing the vapor into a liquid (the distillate), leaving behind nonvolatile solid substances of a drilling fluid. The distillate is the water and/or oil content of a fluid.
Divided deck. A deck having a screening surface longitudinally divided by partition(s).
Dog leg. The elbow caused by a sharp change of drilling direction in the well bore.
Double flute. The flutes or leads advancing simultaneously at the same angle and 180 apart. See: flute, flight, blade.
Downstream venturi. See: venturi.
Drill bit. The cutting or boring element at the end of the drill string.
Drill stem test (DST). A postdrilling and preproduction test that allows formation fluids to flow into the drill pipe under controlled conditions, to determine whether oil and/or gas in commercial quantities have been encountered in the penetrated formations.
Drill string. The column of drill pipe with attached tool joints that transmits fluid and rotational power from the kelly to the drill collars and bit.
Drilled solids. Formation solids that enter the drilling-fluid system, whether produced by a bit or from the side of the borehole. See lowgravity solids, cuttings.
Drilled-solids fraction. The average volume fraction of drilled solids maintained in the drilling fluid over a specified interval of footage.
Drilled-solids removal system. All equipment and processes used while drilling a well that remove the solids generated from the hole and carried by the drilling fluid, that is, settling, screening, desanding,desilting, centrifuging, and dumping.
Drilling fluid. Term applied to any liquid or slurry pumped down the drill string and up the annulus of a hole to facilitate drilling. See: drilling mud, mud.
Drilling-fluid additive. Any material added to a drilling fluid to achieve a particular effect.
Drilling-fluid analysis. Examination and testing of the drilling fluid to determine its physical and chemical properties and functional ability. See: API RP 13B.
Drilling-fluid cycle time. The time necessary to move a fluid from the kelly bushing to the flowline in a borehole. The cycle, in minutes, equals the barrels of drilling fluid in the hole minus pipe displacement divided by barrels per minute of circulation rate:

Drilling-fluid engineer. One versed in drilling fluids, rig operations, and solids and waste management, whose duties are to manage and maintain the drilling-fluid program at the well site.
Drilling-fluid program. A proposed plan or procedure for application and properties of drilling fluid(s) used in drilling a well with respect to depth. Some factors that influence the drilling-fluid program are the casing program and formation characteristics such as type, competence, solubility, temperature, pressure, etc.
Drilling in. The drilling operation starting at the point of drilling into the producing formation.
Drilling mud. See: drilling fluid, which is the preferred term.
Drilling out. The operation of drilling out of the casing shoe after the cementing of a casing or liner in place. Drilling out of the casing is done before further hole is made or completion attempted.
Drilling rate. The rate at which hole depth progresses, expressed in linear units per unit of time (including connections) as feet/minute or feet/hour. See: ROP, rate of penetration, penetration rate.
Dry bottom. An adjustment to the underflow opening of a hydrocyclone that causes a dry beach, usually resulting in severe plugging. See: dry plug.
Dry plug. The plugging of the underflow opening of a hydrocyclone caused by operating with a dry bottom.
Dryer. A shale shaker with a fine mesh screen that removes excess fluid and fine solids from discarded material from other shale shakers and hydrocyclones. Typically, this is used to decrease the liquid waste from a drilling fluid to decrease discarded volumes. See mud cleaner.
Dual wound motors. Motors that may be connected to either of two voltages and starter configurations.
Dynamic. The state of being active or in motion, as opposed to static.

Drilling fluids processing glossary C

Cable tool drilling. A method of drilling a well by allowing a weighted bit (or chisel) at the bottom of a cable to fall against the formationbeing penetrated. The cuttings are then bailed from the bottom of thewell bore with a bailer. See: rotary drilling.
Cake consistency. According to API RP 13B, can be described as hard,soft, tough, rubbery, firm, etc.
Cake thickness. (1) A measurement of the thickness of the filter cake deposited by a drilling fluid against a porous medium, usually filter paper, according to the standard API filtration test. Cake thickness is usually reported in 32nds of an inch or millimeters. (2) A parameter of the filter cake deposited on the wall of the borehole. See: filter cake,wall cake.
Calcium. One of the alkaline earth elements with a valence of 2 and an atomic weight of about 40. Calcium compounds are a common cause of the hardness of water. Calcium is also a component of lime, gypsum, limestone, etc.
Calcium carbonate. (1) CaCO3. An acid soluble calcium salt sometimes used as a weighting material (limestone, oyster shell, etc.) in specializeddrilling fluids. (2) A term used to denote a unit and/or standard to report hardness. See: limestone.
Calcium chloride. CaCl2. A very soluble calcium salt sometimes added to drilling fluids to impart special inhibitive properties, but used primarily to increase the density of the liquid phase (water) in completion fluids and as an inhibitor to the water phase of invert oil emulsion drilling fluids.
Calcium contamination. Dissolved calcium ions in sufficient concentration to impart undesirable properties in a drilling fluid, such as flocculation, reduction in yield of bentonite, increase in fluid loss, etc. See: calcium sulfate, gyp, anhydrite, lime, calcium carbonate.
Calcium hydroxide. Ca(OH)2. The active ingredient of slaked lime. It isalso the main constituent in cement (when wet) and is referred to as‘‘lime’’ in field terminology. See: lime.
Calcium sulfate. Anhydrite, CaSO4, plaster of Paris, CaSO4
12H2O, and gypsum, CaSO4
2H2O. Calcium sulfate occurs in drilling fluids as a contaminant or may be added as a commercial product to certain drilling fluids to impart special inhibitive properties. See: gypsum,anhydrite.
Calcium-treated drilling fluids. Drilling fluids to which quantities of soluble calcium compounds have been added or allowed to remain from the formation drilled in order to impart special inhibitive properties to the drilling fluid.
Calendered wire cloth. Wire cloth that has been passed through a pair of heavy rollers to reduce the thickness of the cloth or flatten the intersections of the wire and produce a smooth surface. This process is usually done to the coarser backing cloths. See: market grade cloth,mill grade cloth.
Capacity. The maximum volume flow rate at which a solids-control device is designed to operate without detriment to separation. See: feed capacity, solids discharge capacity.
Cascade. Gravity-induced flow of fluid from one unit to another.
Cascade shaker arrangement. System that processes the drilling fluid through two or more shakers in series.
Casing. Steel pipe placed in an oil or gas well to prevent the wall of the hole in a drilled interval from caving in, as well as to prevent movement of fluids from one formation to another.
Cation. The positively charged particle in the solution of an electrolyte,which, under the influence of an electrical potential, moves toward the cathode (negative electrode). Examples are Naþ, Hþ, NH4þ, Caþ,Mgþþ, and Alþþþ.
Cation exchange capacity. The total amount of cations adsorbed on the basal surfaces or broken bond edges of a clay sample, expressed in milliequivalents per 100 grams of dry clay. See: base exchange,methylene blue titration, methylene blue test, MBT, CEC.
Caustic. See: sodium hydroxide.
Caustic soda. See: sodium hydroxide.
Cave in. A severe form of sloughing. See: sloughing.
Cavernous formation. A formation having voluminous voids, usually the result of dissolution by formation waters that or may not be still present.
Caving. Caving is a severe form of sloughing. See: sloughing, heaving.
Cavitation. Cavitation is the formation and collapse of low-pressure bubbles in a liquid. In centrifugal pumps it occurs when the pressure within the impeller chamber decreases below the vapor pressure of the liquid. As these vapor bubbles move to the impeller tip and into a higher-pressure region, they implode or collapse. The pressure at the suction entry may be considerably below atmospheric pressure if the pressure loss in the suction line is too large, if the flow rate from the pump is too large for the inlet size, or if the fluid must be lifted to excessive heights. As the bubbles move out to the tips of the impeller, they implode, releasing a large amount of energy that can actually chip metal pieces from the impeller blade. Cavitation frequently sounds like the centrifugal pump is pumping gravel. See:centrifugal pump.
CEC. See: cation exchange capacity.
Cement. A mixture of calcium aluminates and silicates made by combining lime and clay while heating. Slaked cement containsabout 62.5% calcium hydroxide, which can cause a major problem when cement contaminates drilling fluid.
Centipoise (cP). Unit of viscosity equal to 0.01 Poise. Poise equals 1 dynesecond per square centimeter. The viscosity of water at 20Celsius is 1.005 cP
(1 cP¼0.000672 lb/ft sec).
Centrifugal force. That force which tends to impel matter outward from the center of rotation. See: g force.
Centrifugal pump. A machine for moving fluid by spinning it using a rotating impeller in a pump casing with a central inlet and a tangential outlet. The path of the fluid is an increasing spiral from the inlet at the center to the outlet, tangent to the annulus. In the annular space between the impeller vane tips and the casing wall, the fluid velocity is roughly that of the impeller vane tips. Useful work is produced by the pump when some of the spinning fluid flows out of the casing tangential outlet into the pipe system. Power from the motor is used to accelerate the fluid coming into the inlet up to the speed of the fluid in the annulus. (Some of the motor power is expended as friction of thefluid in the casing and impeller.)
Centrifugal separator. A general term applicable to any device using centrifugal force to shorten and/or control the settling time required to separate a heavier mass from a lighter mass.
Centrifuge. A centrifugal separator, specifically a device rotated by an external force for the purpose of separating materials of different masses. This device is used for the mechanical separation of solids from a drilling fluid. Usually in a weighted drilling fluid, it is used to eliminate colloidal solids. In an unweighted drilling fluid, it is used to remove solids larger than colliods. The centrifuge uses high-speed mechanical rotation to achieve this separation, as distinguished from the cyclone type of separator, in which the fluid energy alone provides the separating force. See: hydrocyclone, desander, desilter.
Ceramics. A general term for heat-hardened clay products, which resist abrasion; used to extend the useful life of wear parts in pumps and hydrocyclones.
Check/suction section. The last active section in the surface system. It provides a location for the rig pump and drilling-fluid hopper suction.This section should be large enough to check and adjust drilling-fluid properties before the drilling fluid is pumped downhole.
Chemical barrel. A container in which soluble chemicals can be mixed with a limited amount of fluid prior to addition to the circulating system.
Chemical treatment. The addition of chemicals (such as caustic,thinners, or viscosifiers) to the drilling fluid to adjust the drillingfluid properties.
Chemicals. In drilling-fluid terminology, a chemical is any material that produces changes in the low-shear-rate viscosity, yield point, gel strength, fluid loss, pH, or surface tension.
Choke. An opening, aperture, or orifice used to restrict a rate of flow or discharge.
Chromate. A compound in which chromium has a valence of 6, for example, sodium dichromate. Chromate may be added to drilling fluids either directly or as a constituent of chrome lignites or chrome lignosulfonates to assist with rheology stabilization. In certain areas,chromate is widely used as an anodic corrosion inhibitor, often inconjunction with lime.
Chrome lignite. Mined lignite, usually leonardite, to which chromate has been added and/or reacted. The lignite can also be causticized with either sodium or potassium hydroxide. The chrome lignite is used for rheology stabilization and filtration control of the drilling fluid.
Circular motion. A shale shaker screen moves in a uniform circular motion when the vibrator is located at the center of gravity of the vibrating basket.
Circulation. The movement of drilling fluid through the flow system on a drilling or workover rig. This circulation starts at the suction pit and goes through the mud pump, drill pipe, bit, annular space in the hole, flowline, fluid pits, and back again to the suction pit. The time involved is usually referred to as circulation time. See: reverse circulation.
Circulation rate. The volume flow rate of the circulating drilling fluid, usually expressed in gallons per minute or barrels per minute. See:flow rate.
Clabbered. A slang term used to describe moderate to severe flocculation of drilling fluid due to various contaminants. See: gelled up.
Clarification. Any process or combination of processes the primary purpose of which is to reduce the concentration of suspended matter in liquid.
Clay. (1) A soft, variously colored earth, commonly hydrous silicatesof alumina, formed by the decomposition of feldspar and other aluminum silicates. Clay minerals are essentially insoluble in water but disperse under hydration, grinding, or velocity effects. Shearing forces break down the clay particles to sizes varying from submicron particles to particles 100 microns or larger.  (2) Solids particles of less than 2 micrometer equivalent spherical diameter. See: attapulgite clay, bentonite, high yield clay, low yield clay, and natural clays.
Clay extender. Substances, usually high-molecular-weight organic compounds, that when added in low concentrations to a bentonite or to other specific clay slurries, will increase the low-shear-rate viscosity of the system. An example would be polyvinyl acetate-maleic anhydride copolymer. See: low solids drilling fluids.
Clay-size particles. See: clay.
Closed loop mud systems. A drilling-fluid processing system that minimizes the liquid discard. Usually as much as possible of the liquid phase normally separated with drilled solids is returned to the active system.
Closed loop systems (pressurized). In underbalanced drilling, this refers to a system in which formation fluid is contained in tanks and not exposed to the atmosphere until sent to the flare line or the holding tank.
CMC. Ceramic matrix compound(s). See: sodium carboxymethylcelluose.
Coagulation. The destabilization and initial aggregation of colloidal and finely divided suspended matter by the addition of a floc-forming agent. See: floc.
Coalescence. (1) The change from a liquid to a thickened curdlike state by chemical reaction. (2) The combination of globules in an emulsion caused by molecular attraction of the surfaces.
Coarse solids. Solids larger than 2000 microns in diameter.
Coating. (1) A material adhering to a surface to change the properties of the surface. (2) A condition in which material forms a film that covers the apertures of the screening surface. See: blinding, plugging.
Cohesion. The attractive forces between molecules of the same kind, that is, the force that holds the molecules of a substance together.
Colloid. A particle smaller than 2 microns. The size and electrical charge of these particles determine the different phenomena observed with colloids, for example, Brownian movement. See: clay, colloidal solids.
Colloidal composition. A colloidal suspension containing one or more colloidal constituents.
Colloidal matter. Finely divided solids that will not settle but may be removed by coagulation.
Colloidal solids. Particles smaller than 2 microns. These are so small that they do not settle out when suspended in a drilling fluid. Commonly used as a synonym for clay. See: clay, colloid.
Colloidal suspension. Finely divided particles that are so small that they remain suspended in a liquid by Brownian movement.
Combining weight. See: equivalent weight.
Conductance. The permeability of a shaker screen per unit thickness of the screen, measured in units of kilodarcys/millimeter, while the screen is stationary.
Conductivity. Measure of the quantity of electricity transferred across unit area per unit potential per unit time. It is the reciprocal of resistivity.Electrolytes may be added to a fluid to alter its conductivity. See: resistivity.
Cone. See: hydrocyclone, hydroclone.
Connate water. Water trapped within sedimentary deposits, particularly as hydrocarbons displaced most of the water from a reservoir.
Consistometer. A thickening time tester having a stirring apparatus to measure the relative thickening time for drilling fluid or cement slurries under predetermined temperatures and pressures. See: API RP 10B.
Contamination. In a drilling fluid, the presence of any material that may tend to harm the desired properties of the drilling fluid.
Continuous phase. (1) The fluid phase that completely surrounds the dispersed phase. (2) The fluid phase of a drilling fluid: either water, oil, or synthetic oil. The dispersed (noncontinuous) phase may be solids or liquid.
Controlled aggregation. The condition in which the clay platelets are maintained stacked by a polyvalent cation, such as calcium.
Conventional drilling fluid. A drilling fluid containing essentially clay and water. Also called conventional mud.
Conventional shale shakers. Usually refers to device that vibrates screens with a circular or an unbalanced elliptical motion. These shale shakers are usually limited to processing drilling fluid through screens up to 100 mesh.
Conveyor. A mechanical device for moving material from one place to another. In a decanting centrifuge, this is a hollow hub fitted with flights rotating in the same direction but at a different speed than the centrifuge bowl. These flights are designed to move the coarse solids out of the bowl and are part of the conveyor.
Copolymer. A substance formed when two or more substances polymerize at the same time to yield a product that is not a mixture of separate polymers but a complex substance having properties different from either of the base polymers. Examples are polyvinylacetate-maleic anyhdride copolymer (clay extender and selective
flocculant), acrylamide-carboxylic acid copolymer (total flocculant),etc. See: polymer.
Corrosion. A chemical degradation of a metal by oxygen in the presence of moisture. An oxide is the by-product of corrosion.
Corrosion inhibitor. An agent that, when added to a system, slows down or prevents a chemical or corrosion. Corrosion inhibitors are used widely in drilling and producing operations to prevent corrosion of metal equipment exposed to hydrogen sulfide, carbon dioxide, oxygen,saltwater, etc. Common inhibitors added to drilling fluids are filming amines, chromates, and oxygen scavengers.
Crater. The formation of a large funnel-shaped cavity at the top of a hole resulting from either a blowout or from caving.
Creaming of emulsions. The settling or rising of particles from the dispersed phase of an emulsion as observed by a difference in color shading of the layers formed. This separation can be either upward or downward, depending on the relative densities of the continuous and dispersed phases.
Created fractures. Induced fractures by means of hydraulic or mechanical pressure exerted on the formation by the drill string and/or circulating fluid.
Critical velocity. That velocity at the transitional point between laminar and turbulent types of fluid flow. This point occurs in the transitional range of Reynolds numbers between approximately 2000 to 3000.
Crown. The curvature of a screen deck or the difference in elevation between its high and low points. See: bow.
Cryogenic (nitrogen). Nitrogen in its liquid form.
Cubic centimeter (cc). A metric-system unit for the measure of volume. A cube measuring 1 centimeter on each side would have a volume of 1 cubic centimeter. It is essentially equal to the milliliter, with which it is commonly used interchangeably. One cc of water at room temperature weighs approximately 1 gram.
Cut point. Cut point curves are developed by dividing the mass of solids in a certain size range removed by the total mass of solids in that size range that enters the separation device. A cut point usually refers to the size of particle that has a 50% chance of being discarded. See median cut.
Cutt points (pronounced ‘‘Koot’’). The equivalent spherical diameters corresponding to the ellipsoidal volume distribution of a screen’s opening sizes, as determined by image analysis. See: API RP 13E.
Cuttings. The pieces of formation dislodged by the bit and brought to the surface in the drilling fluid. Field practice is to call all solids removed by the shaker screen ‘‘cuttings,’’ although some can be sloughed material from the wall of the borehole. See: drilled solids, low-gravity solids, samples.
Cyclone. A device for the separation of solid particles from a drilling fluid. The most common cyclones used for solids separation are a desander or desilter. In a cyclone, fluid is pumped tangentially into a cone, and the fluid rotation provides enough centrifugal force to separate particles by mass (weight). See: desander, desilter, hydrocyclone,hydroclone.
Cyclone bottom. See: apex, apex valve.

Drilling fluids processing glossary B

Backpressure. The frictional or blocking pressure opposing fluid flow ina conduit. See: differential pressure.

Back tank. The compartment on a shale shaker that receives drillingfluid from the flowline. See: possum belly, mud box.

Backing plate. The plate attached to the back of screen cloth(s) for support.

Backup screen. See: support screen.

Baffles. Plates or obstructions built into a compartment to change thedirection of fluid flow.

Balanced design hydrocyclone. A hydrocyclone that has the lower apex adjusted to the diameter of the cylinder of air formed within the cone by the cyclonic forces of drilling fluid spinning within cone. This tends to minimize liquid discharge when there are no separable solids.

Balanced elliptical motion. An elliptical motion of a shale shaker screen such that all ellipse axes are tilted at the same angle toward the discharge end of the shale shaker.

Ball valve. A valve that uses a spherical closure with a hole through its center and rotates 90 to open and close.

Barite. Natural barium sulfate, BaSO4, is used for increasing the density of drilling fluids. The API standard requires a minimum of 4.20 specific gravity. Commercial barium sulfate ore can be produced from a single ore or a blend of ores and may be a straight-mined product or processed by flotation methods. It may contain minerals other than barium sulfate. Because of mineral impurities, commercial barite may vary in color from off-white to gray to red or brown. Common accessory minerals are silicates such as quartz and chert, carbonate compounds such as siderite and dolomite, and metallic oxide and sulfide compounds.

Barite recovery efficiency. Barite recovery efficiency is the ratio of the mass flow rate of barite returning to a drilling fluid from a solids control device divided by the mass flow rate of barite in the feed to the solids-control device.

Barium sulfate. BaSO4. See: barite.

Barrel (bbl). A volumetric unit of measure used in the petroleum industry consisting of 42 U.S. gallons.

Barrel equivalent. One gram of material in 350 ml of fluid is equivalent to a concentration of 1 lb of that material in an oilfield barrel of fluid.See: barrel, pound equivalent.

Base. A compound of a metal, or a metal-like group, with hydrogen and oxygen in the proportions that form an OH– radical, when ionized in an aqueous solution, yielding excess hydroxyl ions. Bases are formed when metallic oxides react with water. Bases increase the pH. Examples of bases are caustic soda, NaOH; and lime, Ca(OH)2.

Base exchange. The replacement of the cations associated with the surface of a clay particle by another species of cation, for example,the substitution of sodium cations by calcium cations on the surface of a clay particle. See: methylene blue titration, methylene blue test, MBT, cation exchange capacity, CEC.

Basicity. pH value above 7. Ability to neutralize or accept protons from acids. See: pH.

Basket. That portion of a shale shaker containing the deck upon which the screen(s) is mounted; supported by vibration isolation members connected to the bed.

Beach. Area between the liquid pool and the solids discharge ports in a decanting centrifuge or hydrocyclone.

Bed. Shale shaker support member, consisting of mounting skid or frame with or without bottom, flow diverters to direct screen underflow to either side of the skid, and mountings for vibration isolation members.

Bentonite. A colloidal clay, largely made up of the mineral sodium montmorillonite, a hydrated aluminum silicate. Used for developing a low shear rate viscosity and/or good filtration characteristics in water-based drilling fluids. The generic term ‘‘bentonite’’ is not an exact mineralogical name, nor is the clay of definite mineralogical

composition. See: gel, montmorillonite.

Bentonite (clay) extender. Additive that interacts with clay in a drilling fluid to boost viscosity; usually this at a low to moderate concentration of polymer and depends on the polymer/clay ratio.

Bernoulli Principle. One means of expressing Newton’s Second Law of Physics, that is, concerning conservation of energy. Roughly stated,this principle demonstrates that the sum of pressure and velocity through or over a device represents equal quantities, neglecting the effects of losses due to friction and/or increases by adding energy with external devices such as pumps.

Bicarb. See: sodium bicarbonate.

Bingham model. A mathematical description that relates shear stress to shear rate in a linear manner. This model requires only two constants (plastic viscosity and yield point) and is the simplest rheological model possible to describe a non-Newtonian liquid. It is very useful for analyzing drilling fluid problems and treatment. See: viscosity, pseudoplastic fluid, plastic viscosity, yield point, gel strength.

Blade. See: flight, flute.

Blinding: A reduction of open area in a screening surface caused by coating or plugging. See: coating, plugging.

Blooie line. The flowline for air or gas drilling.

Blowout. An uncontrolled escape of drilling fluid, gas, oil, or water from the well caused by the formation pressure being greater than the hydrostatic head of the fluid being circulated in the well bore. See: kick, kill fluid.

Bonded screens. Multiple screens bonded together with plastic to form a multilayered screen or screens bonded to a metal support plate.

Bonding material. Material used to secure screen cloth to a backing plate or support screen.

Bottom flooding. The behavior of a hydrocyclone when the underflow discharges whole drilling fluid rather than separated solids.

Bound liquid. Adsorbed liquid. See: absorb, absorption, adsorb, adsorption, adsorbed liquid.

Bow. See: crown.

Bowl. The outer rotating chamber of a decanting centrifuge.

Brackish water. Water containing low concentrations of any soluble salts.

Break circulation. To start movement of the drilling fluid after it has been quiescent in a borehole.

Bridge. An obstruction in a well formed by the intrusion of subsurface formations and/or cuttings or material, which prevents a tubular string from moving down a borehole.

Brine. Water containing a high concentration of common salts such as sodium chloride, calcium chloride, calcium bromide, zinc bromide, etc.

Bromine value. The number of centigrams of bromine that are absorbed by 1 gram of oil under certain conditions. The bromine check is a test for the degree of unsaturation of a given oil.

Brownian movement. Continuous, irregular motion exhibited by particles suspended in a liquid or gaseous medium, usually as a colloidal dispersion.

BS&W. Base sediment and water.

Buffer. Any substance or combination of substances that, when dissolved in water, produces a solution that resists a change in its hydrogen ion concentration upon the addition of an acid or base.