Tuesday, August 18, 2015

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
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
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
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.

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