Drilling fluids processing glossary E

Eductor. (1) A device utilizing a fluid stream discharging under high pressure from a jet through an annular space to create a vacuum. When properly arranged, it can evacuate degassed drilling fluid from a vacuum-type degasser. (2) A device using a high-velocity jet to create a vacuum that draws in liquid or dry material to be blended with drilling fluid.
Effective screening area. The portion of a screen surface available for solids separation.
Effluent. A discharge of liquid. Generally used to describe a stream of liquid after some attempt at separation or purification has been made. See: discharge.
Elastomer. Any rubber or rubber-like material (such as polyurethane).
Electric logging. Logs run on a wire line to obtain information concerning the porosity, permeability, density, and/or fluid content of the formations drilled. The drilling-fluid characteristics may need to be altered to obtain good logs.
Electrolyte. A substance that dissociates into charged positive and negative ions when in solution or a fused state. This electrolyte will then conduct an electric current. Acids, bases, and salts are common electrolytes.
Elevation head. The pressure created by a given height of fluid. See: hydrostatic pressure head.
Emulsifier. A substance used to produce a mixing of two liquids that do not solubilize in each other or maintain a stable mixture when agitated in the presence of each other. Emulsifiers may be divided into ionic and nonionic agents, according to their behavior. The ionic types may be further divided into anionic, cationic, and, depending on the nature of the ionic groups.
Emulsion. A substantially permanent heterogeneous mixture of two or more liquids that do not normally dissolve in each other but are held in a dispersed state, one within the other. This dispersion is accomplished by the combination of mechanical agitation and presence of fine solids and/or emulsifiers. Emulsions may be mechanical, chemical, or a combination of the two. Emulsions may be either oil-in-water or water-in-oil. See: interfacial tension, surface tension.
Emulsoid. Colloidal particle that takes up water.
Encapsulation. The process of totally enclosing electrical parts or circuits with a polymeric material (usually epoxy).
End point. Indicates the end of a chemical testing operation when a clear and definite change is observed in the test sample. In titration, this change is frequently a change in color of an indicator or marker added to the solution, or the disappearance of a colored reactant.
Enriching. The process of increasing the concentration of a flammable gas or vapor to a point at which the atmosphere has a concentration of that flammable gas or vapor above its upper flammable or explosive limit.
Extreme pressure (EP) additive. See: extreme pressure lubricant.
EPL. Extreme pressure lubricant. See: extreme pressure lubricant. epm.
Equivalents per million. See: equivalents per million, parts per million.
Equalizer. An opening for flow between compartments in a surface fluid holding system.
Equivalent circulating density (ECD). The effective drilling-fluid weight at any point in the annulus of the well bore during fluid circulation. ECD includes drilling-fluid density, cuttings in the annulus, and annular pressure loss. See: annular pressure loss.
Equivalent spherical diameter (ESD). The theoretical dimension usually referred to when the sizes of irregularly shaped particles are discussed.These dimensions can be determined by several methods, such as settling velocity, electrical resistance, and light reflection. See: particle size.
Equivalent weight. The atomic weight or formula weight of an element, compound, or ion divided by its valence. Elements entering into combination always do so in quantities to their equivalent weights. Also known as combining weight.
Equivalents per million (epm). Unit chemical weight of solute per million unit weights of solution. The epm of a solute in solution is equal to the ppm (parts per million) divided by the equivalent weight. See: parts per million.
ESD. Equivalent spherical diameter. See: equivalent spherical diameter,particle size.
Extreme pressure lubricant (EPL). Additives to the drilling fluid that impart lubrication to bearing surfaces when subjected to extreme pressure conditions.

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.