Enhancing Drilling Efficiency: Introducing Our High-Capacity Saline Water Filtration Unit

 In the demanding environment of oilfield operations, maintaining the integrity of drilling fluids is paramount. We are proud to introduce our robust Saline Water Filtration Unit, a critical component designed for integration into complete solids control systems. This unit is engineered to deliver reliable, high-volume filtration essential for modern drilling projects.

Designed for Performance and Reliability:

This skid-mounted unit features a two-stage filtration process to ensure fluid clarity. It utilizes a primary basket filter and a secondary bag filter to achieve a final filtration precision of 2 microns, protecting downstream equipment. With a guaranteed flow rate exceeding 1 cubic meter per minute (250 GPM), it meets the high-demand requirements of active drilling sites.

Built for Safety and Harsh Conditions:

Understanding the operational environment, the unit is constructed with durability in mind:

Material: Major components are made from corrosion-resistant 304 Stainless Steel.

Safety Compliance: The entire electrical system, including the 15kW pump motor and control cabinet, is certified for hazardous areas (Exd IIB T4) and carries international ATEX/IECEx certifications.

Rugged Design: It comes with integrated lifting lugs and forklift pockets for easy transport and positioning on-site.

Ideal for:

This filtration unit is a perfect fit for land and offshore drilling rigs, as well as other industrial applications requiring high-purity saline water filtration.

Discover how our filtration solutions can optimize your operations. Learn more about our full range of solids control equipment.

Enhancing XJ750 Workover Rig Performance with Integrated Solids Control

For well intervention and workover operations using XJ750 rigs, effective solids control is critical for cost management and operational success. AIPU’s mobile solids control system is engineered specifically for these applications. It tackles the unique challenges of workover fluid management—removing fine solids, maintaining fluid density and viscosity, and minimizing waste volumes. This article explores how a dedicated solids control package can improve the efficiency, environmental compliance, and profitability of your workover projects.

Read more & explore solutions: aipusolidcontrol.com

#aipuSolidControl #SolidsControl #WorkoverRig #XJ750 #WellWorkover #FluidManagement #OilfieldMaintenance #DrillingWasteManagement #OilAndGas #EnergySector #AIPU

Decanter Centrifuge AIPU Solid Control

Selecting and Operating for Optimal Performance

Not all centrifuges are created equal. Key operational variables must be considered:

• Bowl Speed: Higher G-force improves separation efficiency for finer particles.

• Conveyor Differential Speed: This controls the dryness of the discharged solids cake. A lower differential allows for a longer residence time and a drier cake.

• Pool Depth: Adjusted by weir plates, a deeper pool provides finer liquid clarification, while a shallower pool yields a drier solids cake.

• Feed Rate and Properties: The centrifuge must be sized and configured to handle the specific flow rate and mud properties of the operation.

Drilling fluid process glossary O

Oblong mesh. A screen cloth that has more openings per inch in one direction than in the perpendicular direction. For example, a 70×30 mesh has 70 openings per inch in

one direction and 30 openings per inch in the perpendicular direction, creating a rectangular opening. The smaller opening dimension controls the sizing of spherical
material. See: rectangular screen.
Oblong weave. See: oblong mesh.
OD. Outside diameter of a pipe.
Ohm. The measurement of resistance or electrical friction.
Oil-based drilling fluid. The term ‘‘oil-based mud’’ is applied to a special type of drilling fluid in which oil is the continuous phase and water the dispersed phase.

Oil-based drilling fluid contains from 1 to 5% water emulsified into the system with lime and emulsifiers. Oil-based muds are differentiated from invert emulsion muds

(both water-in-oil emulsions) by the amounts of water used, the method of controlling viscosity, the thixotropic properties, wall-building materials, and fluid loss. See:

invert oil emulsion drilling fluid.
Oil breakout. Oil that has risen to the surface of a drilling fluid. This oil had been previously emulsified in the drilling fluid or may derive from oil-bearing formations

that have been penetrated.
Oil content. The oil content of any drilling fluid is the amount of oil in volume percentage.
Oil immersion. An oil-filled construction in which an electrical device has no electrical connections, joints, terminals, or arcing parts at or above the normal oil level.
Oil wet. A surface on which oil easily spreads. If the contact angle of an oil droplet on a surface is less than 90 , the surface is oil wet. See: lipophilic, water wet.
Oil-in-water emulsion drilling fluid. Any conventional or special waterbase drilling fluid to which oil has been added. A drilling fluid in which the oil content is usually

kept between 3 and 7% and seldom over 10% (it can be considerably higher). Commonly called ‘‘emulsion mud.’’ The oil becomes the dispersed phase and may be

emulsified into the mud either mechanically or chemically. The oil is emulsified into freshor saltwater with a chemical emulsifier
Overflow. The discharge stream from a centrifugal separation that normally contains a higher percentage of liquids than does the feed.
Overflow header. A pipe into which two or more hydrocyclones discharge their overflow.
Overslung. Field terminology denoting that the support ribs for the shaker screen are located below the screen surface. See: underslung.

Drilling fluids processing glossary L

LCM. Circulation material. See: lost circulation materials.
Lead. In a decanting centrifuge, the slurry-conducting channel formed by the adjacent walls of the flutes or blades of the screw conveyor.
Leonardite. Anaturally occurring oxidized lignite. See: humic acid, lignin.
Light solids. See: low-gravity solids.
Lignin. Mined lignin is a naturally occurring special lignite, for example, leonardite, produced by strip mining from special lignite deposits. The  active ingredients are the humic acids. Mined lignins are used primarily as thinners, which may or may not be chemically modified. See:  leonardite, humic acid.
Lignosulfonates. Organic drilling-fluid additives derived from by products of the sulfite paper manufacturing process from coniferous woods. Some of the common salts, such as ferrochrome, chrome, calcium, and sodium, are used as deflocculants while other lignosulfonates are used selectively for calcium-treated systems. In large quantities, the ‘‘heavy metal’’ ferrochrome and chrome salts are used for fluid loss control and shale inhibition.
Lime. Ca(OH)2. Commercial form of calcium hydroxide.
Lime-treated drilling fluids. Commonly referred to as ‘‘lime-based’’ muds. These high-pH systems contain most of the conventional freshwater drilling-fluid additives to which slaked lime has been added to impart special inhibition properties. The alkalinities and lime contents of the fluids may vary from low to high. See: calcium-treated drilling fluids.
Limestone. Ca(CO)3. See: calcium carbonate.
Line sizing. Ensuring that the fluid velocity through all piping within the surface system has the proper flow and pipe diameter combination to prevent solids from settling and pipe from eroding. A good rule of thumb is to ensure that fluid flow is between 5 and 9 feet per second, as determined by the following:

Linear motion. Linear motion of a shale shaker screen is produced by two counterrotational motors located above the shaker basket in such a way that a line connecting the two motor axes is perpendicular to a line passing through the center of gravity of the basket. Because the acceleration is applied directly through the center of gravity of the basket, the basket is dynamically balanced; the same pattern of motion will exist at all points along the shaker screen. The resultant screen motion is linear, and the angle of this uniform motion is usually 45° to 60°relative to the shaker screen deck.
Lipophile. Any substance, usually in the colloidal state or an emulsion, that is wetted by oil; that is, it attracts oil or oil adheres to it. See: hydrophile.
Lipophilic. A property of a substance having an affinity for oil or one that is wetted by oil. See: hydrophilic.
Liquid. Fluid that will flow freely and takes the shape of its container.
Liquid-clay phase. See: overflow.
Liquid discharge. See: underflow.
Liquid film. The liquid surrounding each particle discharging from the solids discharge of cyclones and screens. See: bound liquid, free liquid.
Live oil. Crude oil that contains gas and distillates and has not been stabilized or weathered. This oil can cause gas cutting when added to drilling fluid and is a potential fire hazard. See: aromatic hydrocarbons.
Load. A device connected to a motor that is receiving output mechanical power from the motor.
Logging. See: mud logging, electric logging.
Loom. See: warp.
Loss of circulation. See: lost circulation.
Lost circulation. The result of drilling fluid escaping into a formation, usually in fractures, cavernous, fissured, or coarsely permeable beds, evidenced by the complete or partial failure of the drilling fluid to return to the surface as it is being circulated in the hole.
Lost circulation additives. Materials added to the drilling fluid to gain control of or prevent the loss of circulation. These materials are added in varying amounts and are classified as fibrous, flake, or granular.
Lost circulation materials. See: lost circulation additives.
Lost returns. See: lost circulation.
Low-gravity solids. Salts, drilled solids of every size, commercial colloids, lost circulation materials; that is, all solids in drilling fluid, exceptbarite or other commercial weighting materials. Salt is considered a low–specific gravity solid. See: heavy solids, high-gravity solids.
Low-silt drilling fluid. An unweighted drilling fluid that has all the sand and a high proportion of the silts removed and has a substantial content of bentonite or other water–loss–reducing clays.
Low-silt mud. See: low-silt drilling fluid.
Low-solids drilling fluids. A drilling fluid that has polymers, such as ceramic matrix compound (CMC) or xanthan gum (XC) polymer, partially or wholly substituted for commercial or natural clays. For comparable viscosity and densities, a low-solids drilling fluid will have a lower volume percentage solids content. In general, the lower the solids content in a mud, the faster a bit can drill.
Low-solids muds. See: low-solids drilling fluids.
Low-solids nondispersed (LSND) drilling fluids. A drilling fluid to which polymers have been added to simultaneously extend and flocculate bentonite drilled solids. These fluids contain low concentrations of dispersed bentonite and do not contain deflocculants such as lignites, lignosulfonates, etc.
Low-yield clay. Commercial clay chiefly of the calcium montmorillonite type having a yield of approximately 15 to 30 barrels per ton. See: highyield clay, bentonite.
Lyophilic. Having an affinity for the suspending medium, such as bentonite in water.
Lyophlic colloid. A colloid that is not easily precipitated from a solution and is readily dispersible after precipitation by addition of a solvent.
Lyophobic colloid. A colloid that is readily precipitated from a solution  and cannot be redispersed by addition of the solution.

drilling fluids glossary I&J

ID. Inside diameter of a pipe.
Ideal nozzle. Orifice that will pass fluid without friction loss, theoretically.
Impeller. A spinning disc in a centrifugal pump with protruding vanes used to accelerate the fluid in the pump casing.
Indicator. Substances in acid/base titrations that in solution change color or become colorless as the hydrogen ion concentration reaches a definite value. These values vary with the indicator. In other titrations such as chloride, hardness, and other determinations, these substances change color at the end of the reaction.Common indicators are phenolphthalein, methyl orange, and potassium chromate.
Inertia. Force that makes a moving particle tend to maintain its direction or a particle at rest to remain at rest.
Inhibited drilling fluid. A drilling fluid having an aqueous phase with a chemical composition that tends to retard and even prevent (inhibit) appreciable hydration (swelling) or dispersion formation clays and shales through chemical and/or physical reactions. See: calcium-treated drilling fluids, saltwater drilling fluid.
Inhibited mud. See: inhibited drilling fluid.
Initial gel. See: gel strength.
Inlet. The opening through which the feed mud enters a solids-control device. See: feed inlet, feed opening.
Interfacial tension. The force required to break the surface definition between two immiscible liquids. The lower the interfacial tension between the two phases of an emulsion, the greater the ease of emulsification. When the values approach zero, emulsion formation is spontaneous. See: emulsion, surface tension.
Intermediate (solids). Particles whose diameter is between 250 and 2000 microns.
Intercalation. A shale stabilization mechanism that involves penetration of a foreign material, such as a glycol, between clay lamellae in a shale to retard interaction of the clay with water.
Interstitial water. Water contained in the interstices or voids of formations.
Intrinsic safety. A feature of an electrical device or circuit in which any spark or thermal effect from the electrical device or circuit is incapable of causing ignition of a mixture of flammable or combustible material in air.
Invert drilling fluid. See: invert oil emulsion drilling fluid.
Invert oil emulsion drilling fluid. A water-in-oil emulsion in which water (sometimes containing sodium or calcium chloride) is the dispersed phase, and diesel oil, crude oil, or some other oil is the phase. Water addition increases the emulsion viscosity, and oil reduces the emulsion viscosity. The water content exceeds 5% by volume. See. oil-based drilling fluid
Iodine number. The number indicating the amount of iodine absorbed by oils, fats, and waxes, giving a measure of the unsaturated linkages present. Generally, the higher the iodine number, the more severe the destructive action of the oil on rubber.
Ions. Molecular condition due to loss or gain of electrons. Acids, bases, and salts electrolytes), when dissolved in certain solvents, especially water, are more or less dissociated into electrically charged ions or parts of the molecules. Loss of electrons results in positive charges, producing a cation. A gain of electrons in the formation of an anion, with negative charge. The valence of an ion is equal to the number of charges borne by the ion. See: anion, cation.
Irreducible fraction. See: adsorbed liquid, bound liquid.
Jet. See: eductor.
Jet hopper. A device that has a jet that facilitates the addition of drillingfluid additives to the system. See: hopper, mud hopper.
Jetting. The process of periodically removing a portion of the water, drilling fluid, and/or solids from the pits, usually by means of pumping through a jet nozzle to agitate the drilling fluid while simultaneously removing it from the pit.
Jones effect. The net surface tension of all salt solutions first decreases with an increase in concentration, passes through a minimum, and then increases as the concentration is raised. The initial decrease is called the Jones effect.

Drilling fluid glossary H

Hardness (water). The hardness of water is due principally to calcium and magnesium ions. The total hardness is measured in terms of parts per million of calcium carbonate or calcium and sometimes epm of calcium. See: API RP 13B.
Head. The height a column of fluid would stand in an open-ended pipe if it was attached to the point of interest. The head at the bottom of a 1000-ft well is 1000 ft, but the pressure would be dependent on the density of the drilling fluid in the well.
Heaving. The partial or complete collapse of the walls of a hole resulting from internal pressures due primarily to swelling from hydration or formation pressures or from internal stresses. See: sloughing.
Heavy solids. See: high-gravity solids.
Hertz. A unit of frequency: cycles per second.
Heterogeneous. A substance that consists of more than one phase and is not uniform, such as colloids, emulsions, etc. It has different properties in different parts.
High-gravity solids (HGS). Solids purchased and added to a drilling fluid specifically and solely to increase drilling-fluid density. Barite (4.2 specific gravity) and hematite (5.05 specific gravity) are the most common additives used for this purpose. See: low-gravity solids.
High-pH drilling fluid. A drilling fluid with a pH range above 10.5. A high-alkalinity drilling fluid. See: pH.
High-yield clay. A classification given to a group of commercial drilling clay preparations having yield of 35 to 50 bbl/ton, an intermediate rating between bentonite and low-yield clays. High-yield drilling clays are usually prepared by peptizing low-yield calcium montmorillonite clays or, in a few cases, by blending some bentonite with the peptized low-yield clay. See: low-yield clay, bentonite.
HLB. Hydrophilic-lipophilic balance. See: hydrophilic-lipophilic balance.
Homogeneous. Of uniform or similar nature throughout, or a substance or fluid that has at all points the same property or composition.
Hook strips. The hooks on the edges of a screen section of a shale shaker that accept the tension member for screen mounting.
Hook-strip panel. One of the two main screen panel types, which consists of one to three layers of screen bordered by metal strips running parallel to the loom. The metal strips have a U-shaped cross section that allows them to be secured and stretched by the shaker tensioning drawbars. These screens are nonpretensioned. See: Rigid frame panel.
Hopper. A large funnel-shaped or cone-shaped device for mixing dry solids or liquids into a drilling-fluid stream in order to uniformly mix these materials into the slurry. The solids are wetted prior to entry into the drilling-fluid system. The system usually consists of a jet nozzle, an open top hopper, and a downstream venturi. See: mud hopper.
Horsepower. The rate of doing work or of expending mechanical energy; that is, horsepower is work performed per unit of time.
1 hp= 550 ft-lb per sec= 0:7067 Btu per sec:
= 0:7457 kilowatt (rated horsepower, converted to kilowatts
= horsepower x 0:746= kilowatts)
Motor nameplate horsepower is the maximum steady load that the motor can pull without damage.
Horsepower-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-hr= 1.341 hp-hr= 3413 Btu= 2,655,000 ft-lb
Horseshoe effect. The U shape formed by the leading edge of drilling fluid moving down a shale shaker screen. The drilling fluid usually tends to pass through the center of a crowned screen faster than it passes through the edges, creating the U shape.
HTHP. High temperature high pressure.
HTHP filter press. A device used to measure the fluid loss under HTHP conditions. See: HTHP fluid loss.
HTHP fluid loss. The fluid loss measured under HTHP conditions, usually 300 Fahrenheit and 500 psi differential pressure. See: HTHP filter press.
Humic acid. Organic acids of indefinite composition found in naturally occurring leonardite lignite. The humic acids are the active constituents that assist in the positive adjustment of drilling-fluid properties. See: lignin.
Hydrate. A substance containing water combined in molecular form (such as CaSO4 .2H2O). A crystalline substance containing water of crystallization.
Hydration. The act of a substance to take up water by means of absorption and/or adsorption; usually results in swelling, dispersion and disintegration into colloidal particles. See: absorb, absorption, adsorb, adsorbed liquid.
Hydroclone. See: cyclone, hydrocyclone.
Hydrocyclone. Aliquid/solids separation device utilizing centrifugal force for settling. Fluid tangentially and spins inside the cone. The heavier solids settle to the walls of the cone and move downward until they are discharged at the cone bottom (cone apex). The spinning fluid travels partway down the cone and back up to exit out the top of the cone through the vortex finder.
Hydrocyclone balance point. (1) That adjustment of the apex that creates an opening about the same diameter as the air cylinder inside of the hydrocyclone. (2) In the field, to adjust a balanced design hydrocyclone during the setup of the solids-control system so that it discharges only a slight drip of water at the underflow opening.
Hydrocyclone size. The maximum inside working diameter of the cone part of a hydrocyclone.
Hydrocyclone underflow. The discharge stream from a hydroclone that contains a higher percentage of solids than does the feed. See: solids discharge.
Hydrogen ion concentration. A measure of either the acidity or alkalinity of a solution, normally expressed as pH. See: pH.
Hydrolysis. Hydrolysis is the reaction of a salt with water to form an acid or base. For example, soda ash (Na2CO3) hydrolyzes basically, and hydrolysis is responsible for the increase in the pH of water when soda ash is added.
Hydrometer. A floating instrument for determining the specific gravity or density of liquids, solutions, and slurries.
Hydrophile. Any substance, usually in the colloidal state or an emulsion, that is wetted by water; that is, it attracts water or water adheres to it. See: lipophile.
Hydrophilic. A property of a substance having an affinity for water or one that is wetted by water. See: lipophilic.
Hydrophilic lipophilic balance. The relative attraction of an emulsifier for water and for oil. It is determined largely by the chemical composition and ionization characteristics of a given emulsifier. The HLB of an emulsifier is not directly related to its solubility, but it determines the type of an emulsion that tends to be formed. It is an indication of the behavioral characteristics and not an indication of emulsifier efficiency.
Hydrophobe. Any substance, usually in the colloidal state, that is not wetted by water.
Hydrophobic. Any substance, usually in the colloidal state or an emulsion, that is not wetted by water; that is, it repels water or water does not adheres to it.
Hydrostatic pressure head. The pressure exerted by a column of fluid, usually expressed in pounds per square inch. To determine the hydrostatic head in psi at a given depth, multiply the depth in feet by the density in pounds per gallon by the conversion factor, 0.052.
Hydroxide. Designation that is given basic compounds containing the OH– radical. When these substances are dissolved in water, the pH of the solution is increased. See: base, pH.
Hygroscopic. The property of a substance enabling it to absorb water from the air.

drilling fluids processing gloccary G

Galena. Lead sulfide (PbS). Technical grades (specific gravity about 7.0) are used for increasing the density of drilling fluids to points impractical or impossible with barite. Almost entirely used in preparation of ‘‘kill fluids.’’ See: kill fluid.
Gas buster. See: poor boy degasser, mud/gas separator.
Gas cut. Gas entrained by a drilling fluid. See: air cutting, aeration.
Gel. (1) A state of a colloidal suspension in which shearing stresses below a certain finite value fail to produce permanent deformation. The minimum shearing stress that will produce permanent deformation is known as the shear or gel strength of the gel. Gels commonly occur when the dispersed colloidal particles have a great affinity for the dispersing medium, that is, are lyophilic. Thus, gels commonly occur with bentonite in water. (2) A term used to designate highly colloidal, high-yielding, viscosity-building, commercial clays, such as bentonite and attapulgite. See: gel strength.
Gelation. Association of particles forming continuous structures at low shear rates.
Gel cement. Cement having a small to moderate percentage of bentonite added as a filler and/or reducer of the slurry weight. The bentonite may be dry-blended into the mixture or added as a prehydrated slurry.
Gel strength. (1) The ability or measure of the ability of a colloid to form gels. Gel strength is a pressure unit usually reported in lb/100 sq ft. It is a measure of the same interparticle forces of a fluid as determined by the yield point, except that gel strength is measured under static conditions, whereas the yield point is measured under dynamic conditions. The common gel strength measurements are initial, 10-minute, and 30-minute gels. (2) The measured initial gel strength of a fluid is the maximum reading (deflection) taken from a direct-reading viscometer after the fluid has been quiescent for 10 seconds. It is reported in lb/100 sq ft. See: API RP 13B, shear rate, shear stress, thixotropy.
Gelled up. Oilfield slang usually referring to any fluid with a high gel strength and/or highly viscous properties. Often a state of severe flocculation. See: clabbered.
g Factor. The acceleration of an object relative to the acceleration of gravity.
g Force. The centrifugal force exerted on a mass moving in a circular path. See g factor.
Glosses. Explanations or comments to elucidate some difficulty or obscurity in the text; or annotations.
Grains per gallon (gpg). Ppm equals gpgX17.1.
Greasing out. In some cases, certain organic substances, usually fatty acid derivatives, that are added to drilling fluids as emulsifiers, EPLs, etc., may react with ions such as calcium and magnesium to form a water-insoluble, greasy material that separates out from the drilling fluid. This separation process is called greasing out.
Guar gum. A naturally occurring hydrophilic polysaccharide derived from the seed of the guar plant. The gum is chemically classified as a galactomannan. Guar gum slurries made up in clear fresh- or brine water possess pseudoplastic flow properties.
Gum. Any hydrophilic plant polysaccharides or their derivatives that, when dispersed in water, swell to produce a viscous dispersion or solution. Unlike resins, they are soluble in water and insoluble in alcohol.
Gumbo: Small, sticky drilled solids that hydrate as they move up an annulus, forming large of cuttings. Gumbo is characteristically observed with water-based drilling fluids during drilling of shales containing large quantities of smectite clay.
Gunk plug. A volume of bentonite in oil that is pumped in a well to combat lost circulation. the bentonite encounters water, it expands and creates a gunk plug with a very high viscosity and gel structure. The plug may or may not be squeezed. See: diesel oil plug.
Gunning the pits. Mechanical agitation of the drilling fluid in a pit by means of a mud gun. See: mud gun.
Gyp. Gypsum.
Gypsum. Calcium sulfate, CaSO4 2H2O, frequently encountered while drilling. It may occur as thin stringers or in massive formations. See: anhydrite, calcium
sulfate.

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 A

Abnormal pressure. A formation pore pressure that is higher than that
resulting from a water gradient.
Absolute temperature. Temperature related to absolute zero, the
temperature at which all molecular activity ceases. Calculated by
adding 460F to the temperature in Fahrenheit to obtain the absolute
temperature in degrees Rankine or by adding 273C to the
temperature in degrees Celsius to obtain the absolute temperature in
degrees Kelvin.
Absorb. To take in and make part of an existing whole. See: absorption,
adsorption, adsorb, adsorbed liquid, bound liquid.
Absorption. The penetration or apparent disappearance of molecules or
ions of one or more substances into the interior of a solid or liquid.
For example, in hydrated bentonite, the planar water that is held
between the mica-like layers is the result of absorption. See: absorb,
adsorption, adsorb, adsorbed liquid, bound liquid.
Acid. Any chemical compound containing hydrogen capable of being
replaced by elements or radicals to form salts. In terms of the dissociation
theory, it is a compound, which, on dissociation in solution,
yields excess hydrogen ions. Acids lower the pH. Examples of acids or
acidic substances are hydrochloric acid (HCl), sodium acid pyrophosphate
(SAPP), and sulfuric acid (H2SO4). See: pH, acidity.
Acidity. The relative acid strength of liquid as measured by pH. A pH
value below 7. See: pH, acid.
Across-the-line-start. A motor startup method that provides full line
voltage to the motor windings.
Active system. The volume of drilling fluid being circulated to drill
a hole. It consists of the volume of drilling fluid in the hole plus the
volume of drilling fluid in the surface tanks through which the fluid
circulates.
Additions section. A (or the) compartment(s) in a drilling-fluid system
between the removal section and the suction section that provide(s)
a well-agitated location within the fluid circulation system for the
addition of commercial materials.
Adhesion. The force that holds unlike molecules together.
Adsorb. (1) The liquid on the surface of a solid particle that cannot
be removed by draining or centrifugal force. (2) To hold a liquid on
the surface of a solid particle that cannot be removed by draining or
centrifugal force. See: absorption, adsorption, adsorb, adsorbed liquid,
bound liquid.
Adsorbed liquid. The liquid film adhering to the surfaces of solids
particles that cannot be removed by draining, even with centrifugal
force. See: absorb, absorption, adsorption, adsorb, bound liquid.
Adsorption. A surface phenomenon exhibited by a solid (adsorbent) to
hold or concentrate gases, liquids, or dissolved substances (adsorptive)
upon its surface, a property due to adhesion. For example, water, held
to the outside surface of hydrated bentonite, is adsorbed water.
Adsorption refers to liquid that is on the outside of some material,
and absorbed refers to the liquid that becomes part of the material.
See: absorb, absorption, adsorb, adsorbed liquid, bound liquid.
Aerated fluid. Drilling fluid to which air or gas has been deliberately
added to lighten the fluid column.
Aeration. (1) The technique of injecting air or gas in varying amounts
into a drilling fluid for the purpose of reducing hydrostatic head.
(2) The inadvertent mechanical incorporation and dispersion of air
or gas into a drilling fluid. If not selectively controlled, it can be very
harmful. See: air cutting, gas cut.
Agglomerate: The larger groups of individual particles usually originating
in sieving or drying operations.
Agglomeration. A group of two or more individual particles held together
by strong forces. Agglomerates are stable to normal stirring, shaking,
or handling as powder or a suspension. They may be broken by drastic
treatment such as the ball milling of a powder or the shearing of a
suspension.
Aggregate. To gather together, to clump together. A flocculated drilling
fluid will aggregate if flocculent is added.
Aggregation. (1) Formation of aggregates. (2) In drilling fluids, aggregation
results in the stacking of the clay platelets face to face. As a
consequence, the viscosity and gel strength of the fluid decreases.
Agitation. The process of rapidly moving a slurry within a tank to
obtain and maintain a uniform mixture.
Agitator. A mechanically driven impeller used to stir the drilling fluid to
assist in the suspension of solids, blending of additives, and maintenance
of uniform consistency.
Air cutting. The inadvertent mechanical incorporation and dispersion of
air into a drilling fluid system. See: aeration, gas cut.
Airlock. A condition causing a centrifugal pump to stop pumping
because of a large bubble of air or gas in the center of the pump
impeller. This prevents the liquid from entering the pump suction.
Airlocking. See: airlock.
Alkali. Any compound having pH properties higher than the neutral
state. See: base.
Alkalinity. The combining power of a base measured by the maximum
number of equivalents an acid with which it can react to form a salt. In
water analyses, it represents the carbonates, bicarbonates, hydroxides,
and occasionally the borate, silicates, and phosphates in the water.
It is determined by titration with standard acid to certain datum
points. See API RP 13B for specific directions for determination
of phenolphthalein (Pf) and methyl orange (Mf) alkalinities of the
filtrate in drilling fluids and the (Pm) alkalinity of the drilling fluid
itself. See: alkali, base, Pf, Mf, and Pm.
Alum. Aluminum sulfate, Al2(SO4)3, a common inorganic coagulant.
Aluminum stearate. An aluminum salt of stearic acid used as a defoamer.
See: stearate.
Amorphous. The property of a solid substance that does not crystallize
and is without any definite characteristic shape.
Ampere. The measurement of electric flow per second.
Amplitude. The distance from the mean position to the point of maximum
displacement. In the case of a vibrating screen with circular
motion, amplitude would be the radius of the circle. In the case of
straight-line motion or elliptical motion, amplitude would be one half
of the total movement of the major axis of the ellipse; thus, one-half
stroke. See: stroke.
Anhydrite. A mineral compound, CaSO4, that is often encountered
while drilling. It may occur as thin stringers or massive formations.
See: calcium sulfate, gypsum.
Anhydrous. Without water.
Aniline point. The lowest temperature at which equal volumes of freshly
distilled aniline and an oil sample that is being tested are completely
miscible. This test gives an indication of the characteristics (paraffinic,
naphthenic, asphaltic, aromatic, etc.) of the oil. The aniline point of
diesels or crude oils used in drilling fluid is also an indication of
the deteriorating effect that these materials may have on natural or
rubber. The lower the aniline point of a particular oil, the greater its
propensity for damaging rubber parts.
Anion. A negatively charged atom or radical, such as Cl–, OH– , SO–4,
etc., in solution of an electrolyte. Anions move toward the anode
(positive electrode) under the influence of an electrical potential.
Annular pressure loss. The pressure on the annulus required to pump
the drilling fluid from the bottom of the hole to the top of the hole in
the annular space. See: ECD.
Annular velocity. The velocity of a fluid moving in the annulus, usually
expressed in ft/min or m/min.
Annulus. The space between the drill string and the wall of the hole or
the inside surface of the casing. Also called annular space.
Antifoam. A substance used to prevent foam by increasing the surface
tension of a liquid. See: defoamer.
Aperture. (1) An opening in a screen surface. (2) The opening between
the wires in a screen cloth. See: mesh.
Apex. The lower end (conical tip) of a hydrocyclone. See: underflow
opening.
Apex valve. See: apex underflow opening.
API Bulletin RP 13E. Recommended practice for shaker screen cloth
design. Published by the American Petroleum Institute. This is an
alternative method for screen description, which is no longer used by
the industry.
API RP 10B. Recommended Practice (RP) for Testing Well Cement.
Published by the Petroleum Institute (API).
API RP 13B. Recommended Practice for Standard Procedure for
Testing Drilling Fluids at the rig. Published by the American
Petroleum Institute.
API RP 13C. Recommended Practice for Drilling Fluid Systems Process
Evaluation. Published by the American Petroleum Institute.
API filter press. A device used to measure API fluid loss conditions.
See: API fluid loss.
API fluid loss. This fluid loss is measured under ambient conditions.
Usually these are room temperature and 100 psi differential pressure.
API gravity. The gravity (weight per unit volume) of crude oil or other
related fluids as measured by a system recommended by the American
Petroleum Institute (API). It is related to specific gravity by the
following formula:
degree API=[141:5/specific gravity]-131:5
API sand. Solids particles that are too large to pass through a U.S.
Standard No. 200 screen (74-micron openings). Note that particle size
is the only standard. Particles larger than 74 microns are classified
as sand even though they may be shale, limestone, wood, or any other
material. See: API RP 13B, sand, sand content.
Apparent viscosity. The apparent viscosity in centipoise, as determined
by the direct-indicating viscometer is equal to one-half the 600-rpm
reading. It is the viscosity of a fluid at a shear rate of 1022 sec1.
See: viscosity, plastic viscosity, yield point, API RP 13B.
Aromatic hydrocarbons. Hydrocarbons that include compounds containing
aliphatic or aromatic groups attached to aromatic rings.
Benzene is the simplest example. See: live oil.
Asphalt. A natural or mixed blend of solid or viscous bitumen found in
natural beds or obtained as a residue from petroleum distillation.
Asphalt, blends containing asphalt, and altered air-blown, chemically
modified, etc.) asphaltic materials have been added to drilling fluids
for purposes such as lost circulation, emulsification, fluid loss control,
lubrication, seepage loss, shale stability, etc.
Atom. The smallest quantity of an element capable of entering into
chemical combination or that can exist alone.
Atomic weight. The relative weight of an atom of any element as
compared with the weight of 1 atom of oxygen. The atomic weight of
oxygen is 16.
Attapulgite clay. A colloidal, viscosity-building clay used principally in
saltwater drilling fluids to the low shear viscosity. Attapulgite, a special
fuller’s earth, is a hydrous magnesium aluminum silicate that has long,
needle-like platelets, as opposed to the broader, more symmetrical
platelets of bentonite.
Axial flow. Flow from a mechanical agitator in which the fluid first
moves along the axis of the impeller shaft (usually down toward the
bottom of a tank) and then away from the impeller. See: radial flow.