API Recommended Practice 10B Recommended Practice for
Testing Well Cements
1. n. [Drilling Fluids]
The industry-standard
document that provides
guidelines for testing methods
for cements and cement
formulations for use in
well cementing. These
recommended procedures are
commonly modified to
address the specific
conditions of a particular
well.
API Specification 10A – Specification for Cements and
Materials for Well Cementing
English | Español
1. n. [Drilling Fluids]
The industry standard
document that specifies
requirements for API well
cements and specificationtesting methods.
abrasion test
English | Español
1. n. [Drilling Fluids]
A laboratory test to evaluate
drilling-grade weighting
material for potential
abrasiveness. The test
measures weight loss of a
specially shaped, stainlesssteel mixer blade after 20
minutes at 11,000 rpm
running in a laboratory-
prepared mud sample.
Abrasiveness is quantified by
the rate of weight loss,
reported in units of
mg/min. Mineral hardness,
particle size and shape are the
main parameters that affect
abrasiveness of weighting
materials. Some crystalline
forms of hematite grind to a
higher percentage of large
particles than do other forms
and are therefore more
abrasive. Hematites are
harder than barites, grind
courser and are more
abrasive. Thus, a hematite
that is proposed as a
weighting material for mud is
typically a candidate for
abrasion testing.
See: barite, ilmenite, iron
oxide, particle-size
distribution, sand test
absolute volume
English | Español
1. n. [Drilling Fluids]
The volume a solid occupies
or displaces when added to
water divided by its weight,
or the volume per unit mass.
In the oil field, absolute
volume is typically given in
units of gallons per pound
(gal/lbm) or cubic meters per
kilogram (m3/kg).
accretion
English | Español
1. n. [Drilling Fluids]
The mechanism by which
partially
hydrated cuttings stick to
parts of the bottomhole
assembly and accumulate as a
compacted, layered deposit.
acetic acid
English | Español
1. n. [Well Completions,
Drilling Fluids, Well
Workover and
Intervention]
An organic acid used in oiland gas-well
stimulation treatments. Less
corrosive than the commonly
used hydrochloric acid, acetic
acid treatments can be more
easily inhibited or retarded
for treatments of long
duration. This is necessary
particularly in applications
requiring the protection of
exotic alloys or in hightemperature wells. In most
cases, acetic acid is used in
conjunction with hydrochloric
acid and other acid additives.
It can also be used as
a chelating agent.
See: inhibit, retarder
acid
English | Español
1. adj. [Drilling Fluids]
Pertaining to an aqueous
solution, such as a water-
base drilling fluid, which has
more hydrogen ions (H+)
than hydroxyl ions (OH-)
and pH less than 7.
Antonyms: alkaline
See: acidity
2. n. [Well Workover and
Intervention]
A generic term used to
describe a treatment
fluid typically
comprising hydrochloric
acid and a blend of acid
additives. Acid treatments are
commonly designed to
include a range of acid types
or blends, such as acetic,
formic, hydrochloric,
hydrofluoric and fluroboric
acids. Applications for the
various acid types or blends
are based on the reaction
characteristics of the prepared
treatment fluid.
See: acetic
acid, acidity, formic
acid, hydrofluoric acid
acidity
English | Español
1. n. [Drilling Fluids]
A chemical property of an
aqueous system that implies
that there are more hydrogen
ions (H+) in the system, or a
potential to produce more
hydrogen ions, than there are
hydroxyl ions (OH-), or
potential to produce hydroxyl
ions.
Antonyms: alkalinity
See: acid
acrylamide acrylate polymer
English | Español
Diagram of PHPA polymer.
1 of 1
1. n. [Drilling Fluids]
A linear copolymer of
acrylate (anionic) and
acrylamide (nonionic)
monomers, also called
partially-hydrolyzed polyacry
lamide (PHPA). The ratio of
acrylic acid to acrylamide
groups on the polymer chain
can be varied in
manufacturing, as can
molecular weight. Another
variable is the base used
to neutralize the acrylic acid
groups, usually NaOH or
KOH, or sometimes NH4OH.
A concentration of
approximately 10 to 30%
acrylate groups provides
optimal anionic
characteristics for most
drilling applications. Highmolecular weight PHPA is
used as a shale-stabilizing
polymer in PHPA
mudsystems. It is also used
as clay extender, either drymixed into clay or added at
the rig to a lowbentonite mud. PHPA can
also be used
to flocculatecolloidal solids
during clear-water
drilling and for
wastewater cleanup. Low
molecular-weight PHPA is a
clay deflocculant.
Alternate Form: acrylamideacrylate polymer
acrylamide polymer
English | Español
Diagram of acrylamide polymer.
1 of 1
1. n. [Drilling Fluids]
A linear,
nonionic polymer made of
acrylamide monomers,
CH2=CHCONH2 . High
molecular-weight
polyacrylamides are used as
selective flocculants in clearwater drilling, low-solids
muds and wastewater
cleanup. Polymers made of
smaller molecules are used
as clay deflocculants in water
muds, which can contain
hardness ions.
Polyacrylamides are not
nearly as sensitive to salinity
and hardness as
the anionic polyacrylates
(SPA). Also, being nonionic,
they are not as powerful
for flocculation or deflocculat
ion applications. Acrylamide
polymers are, however,
susceptible to hydrolysis and
release ammonia under
hot, alkaline conditions.
See: acrylamide-acrylate
polymer, acrylamido-methylpropane sulfonate
polymer, acrylate
polymer, clay extender, clearwater drilling, colloidal
solids, deflocculant, flocculan
t, low-solids mud, PHPA
mud, vinyl polymer, water
clarification
acrylamide-acrylate polymer
English | Español
Diagram of PHPA polymer.
1 of 1
1. n. [Drilling Fluids]
A linear copolymer of
acrylate (anionic) and
acrylamide (nonionic)
monomers, also called
partially-hydrolyzed polyacry
lamide (PHPA). The ratio of
acrylic acid to acrylamide
groups on the polymer chain
can be varied in
manufacturing, as can
molecular weight. Another
variable is the base used
to neutralize the acrylic acid
groups, usually NaOH or
KOH, or sometimes NH4OH.
A concentration of
approximately 10 to 30%
acrylate groups provides
optimal anionic
characteristics for most
drilling applications. Highmolecular weight PHPA is
used as a shale-stabilizing
polymer in PHPA
mudsystems. It is also used
as clay extender, either drymixed into clay or added at
the rig to a lowbentonite mud. PHPA can
also be used to
flocculate colloidal
solids during clear-water
drilling and for wastewater
cleanup. Low molecularweight PHPA is a
clay deflocculant.
See: acrylamide
polymer, acrylate
polymer, beneficiation, claywater
interaction, copolymer, encap
sulation, flocculant, hardness
ion, hydrolysis, low-solids
mud, potassium
mud, seawater mud, vinyl
polymer
acrylamido methyl propane sulfonate polymer
English | Español
Diagram of AMPS polymer.
1 of 1
1. n. [Drilling Fluids]
A copolymer of 2acrylamido-2methyl propane
sulfonate and
acrylamide. AMPS polymers
are highly watersoluble anionic additives
designed for high-salinity and
high-temperature watermud applications. (Alkylsubstituted acrylamide can be
used instead of ordinary
acrylamide, which lessens its
vulnerability to hydrolysis at
high temperature and
high pH.) Polymers from 0.75
to 1.5 MM molecular weight
are suggested for fluid-loss
control in these difficult
muds. Reference: Perricone
AC, Enright DP and Lucas
JM: "Vinyl Sulfonate
Copolymers for HighTemperature Filtration Contro
l of Water-Base Muds," SPE
Drilling Engineering 1, no. 5
(October 1986): 358-364.
Alternate Form: acrylamidomethyl-propane sulfonate
polymer
acrylamido-methyl-propane sulfonate polymer
English | Español
Diagram of AMPS polymer.
1 of 1
1. n. [Drilling Fluids]
A copolymer of 2acrylamido-2methyl propane
sulfonate and acrylamide.
AMPS polymers are highly
water-soluble anionic
additives designed for highsalinity and high-temperature
water-mud applications.
(Alkyl-substituted acrylamide
can be used instead of
ordinary acrylamide, which
lessens its vulnerability to
hydrolysis at high
temperature and high pH.)
Polymers from 0.75 to 1.5
MM molecular weight are
suggested for fluid-loss
control in these difficult
muds.
Reference:
Perricone AC, Enright DP
and Lucas JM: "Vinyl
Sulfonate Copolymers for
High-Temperature Filtration
Control of Water-Base
Muds," SPE Drilling
Engineering 1, no. 5 (October
1986): 358-364.
Alternate Form: AMPS
See: acrylamide
polymer, copolymer, filtercake
quality, filtration, hydrolysis
acrylate polymer
English | Español
Diagram of acrylate polymer
1 of 1
1. n. [Drilling Fluids]
Linear, anionic polymer made
from
the monomer acrylic acid,
CH2=CHCOO-H+. The acrylic
acid groups are evenly spaced
along the chain. Acrylic acid
polymer neutralized with
NaOH is sodium polyacrylate
(SPA). Polyacrylates are best
utilized in soft water with low
salinity to achieve the
best dispersionand full chain
elongation. Even low
concentrations of hardness
ions, for example,
Ca+2, precipitate polyacrylates
. Low molecular-weight
polyacrylates are used
as clay deflocculants. High
molecular weight polymers
are used for fluid-loss
control and as a clay
extender. As an extender,
SPA is added to bentonite at
the grinding plant. It is also
used at the rig in low-solids
mud. Divalent cations can
negate its benefits as a clay
extender. SPA is highly
efficient when used
to flocculate colloids in
native-solids muds, clearwater muds and wastewater
cleanup. The polymer chain
links together colloidal
solids that can be removed by
gravity settling in shallow pits
or by
applying hydrocyclone, centri
fuge or filtration techniques.
Synonyms: polyacrylate
See: acrylamide
polymer, acrylamide-acrylate
polymer, anion, calcium
contamination, clear-water
drilling, deflocculant, deflocc
ulated
mud, flocculant, hardness
ion, low-solids, nondispersed
mud, native-solids
mud, PHPA mud, sodium
bicarbonate, sodium
carbonate, sodium
polyacrylate, soft
water, water clarification
active sulfide
English | Español
1. n. [Drilling Fluids]
A compound of sulfur that
contains the S-2 ion. Sulfides
can be generated from
soluble iron sulfide minerals
or from sulfate-reducing
bacteria. The term "active
sulfide" is used to denote
compounds that revert to the
highly toxic H2S gas when
acidified with 2-molar citric
acid solution, as opposed to
inert sulfide, which is stable.
Active sulfides include
calcium sulfide and bisulfide
formed when H2S reacts with
lime in an oil-base mud. Their
accumulation constitutes a
safety concern at the rig
because of the risk of
reverting to H2S gas should
an acidic influx occur. They
may be converted to inert
sulfides by adding zinc
oxide.
Reference: Garrett RL,
Carlton LA and Denekas MO:
"Methods
for Field Monitoring of OilBased Drilling Fluids
for Hydrogen Sulfide and
Water Intrusions," SPE
Drilling Engineering 3, no.3
(September 1988): 296-302.
Antonyms: inert sulfide
See: corrosion
coupon, neutralization, sulfid
e
activity of aqueous solutions
English | Español
1. n. [Drilling Fluids]
The escaping tendency,
or vapor pressure, of water
molecules in an aqueous
solution compared with that
of pure water, typically
abbreviated aw. Activity is
expressed mathematically as
the ratio of two vapor
pressures: aw = p/po,
where p is vapor pressure of
the solution and po is vapor
pressure of pure water. The
ratio ranges from near 0 to
1.0 and corresponds to
percent relative
humidity (% RH) of air in
equilibrium with the aqueous
solution. For pure
water, aw = po/po = 1.00 and
RH = 100%. By increasing
the concentration of salt (or
other solutes) in the
solution, aw decreases,
because vapor pressure of the
solution decreases.
However, aw never reaches
zero. Known-activity,
saturated-salt solutions are
used to calibrate RH meters.
Measuring RH of air above
an oil mud is a simple way to
measure the activity (salinity)
of its water phase. Adjusting
the salinity of the water phase
is a way to control movement
of water into or out of shales
that are being drilled with an
oil mud. Chenevert
related aw in oil mud to RH
above the mud sample and
devised a practical test using
an electrohygrometer to
measure RH, called the
"Chenevert Method."
See: balanced-activity oil
mud, calcium
chloride, humidity
meter, hygrometer, inhibit, os
mosis, osmotic
pressure, shale, zinc chloride
acyclic compound
English | Español
1. n. [Drilling Fluids]
One of a group of organic
compounds of carbon (C) and
hydrogen (H) in which the
carbon atoms have linear,
branched chain (open), or
both types of structures.
Aliphatics, as they are
informally called, can be
divided into paraffinic
(saturated) and olefinic
(unsaturated) chain types. The
simplest paraffinic aliphatic
is methane, CH4. The
simplest olefinic aliphatic is
ethylene, C2H6. In drilling
fluids, particularly oil-base
muds, the amounts and types
of hydrocarbon in
the mud can be an important
parameter in overall
performance of the mud.
Synonyms: aliphatic
compound
See: aromatic
hydrocarbon, naphthenic
hydrocarbon, oil-base
mud, soap
aerobic
English | Español
1. adj. [Drilling Fluids]
Referring to a condition or a
situation in which free
oxygen exists in an
environment.
See: biodegradation
2. adj. [Drilling Fluids]
Referring to a condition or a
situation or a living creature,
such as a bacteria, in which
oxygen is required to sustain
life.
Antonyms: anaerobic
agglomeration
English | Español
1. n. [Drilling Fluids]
The formation of groups or
clusters of particles
(aggregates) in a fluid. In
water or in water-base drilling
fluid, clay particles form
aggregates in a dehydrated,
face-to-face configuration.
This occurs after a massive
influx of hardness ions into
freshwater mudor during
changeover to a lime
mud or gyp mud.
Agglomeration results in
drastic reductions in plastic
viscosity, yield point
and gel strength. It is part of
wastewater cleanup and water
clarification. Alum or
polymers
cause colloidal particles
to aggregate, allowing easier
separation.
Synonyms: aggregation
See: clay, clay-water
interaction, colloidal
solids, dewatering, dispersion
, flocculation, greasing
out, wastewater cleanup
aggregate
English | Español
1. n. [Drilling Fluids]
Group or cluster of particles
in a fluid. In water or in
water-base drilling fluid, clay
particles form aggregates in a
dehydrated, face-to-face
configuration. This occurs
after a massive influx of
hardness ions into
freshwater mud or during
changeover to a lime
mud or gyp mud.
Aggregation results in drastic
reductions in plastic
viscosity, yield point
and gel strength. It is part of
wastewater cleanup and water
clarification. Alum or
polymers
cause colloidal particles to
aggregate, allowing easier
separation.
See: agglomeration, aggregati
on, clay, clay-water
interaction, colloidal
solids, dewatering, dispersion
, flocculation, greasing
out, wastewater cleanup
aggregation
English | Español
1. n. [Drilling Fluids]
The formation of groups or
clusters of particles
(aggregates) in a fluid. In
water or in water-base drilling
fluid, clay particles form
aggregates in a dehydrated,
face-to-face configuration.
This occurs after a massive
influx of hardness ions into
freshwater mudor during
changeover to a lime
mud or gyp mud.
Aggregation results in drastic
reductions in plastic
viscosity, yield point and gel
strength. It is part of
wastewater cleanup and water
clarification. Alum or
polymers cause colloidal
particles to aggregate,
allowing easier separation.
Synonyms: agglomeration
See: aggregate, clay, claywater interaction, colloidal
solids, dewatering, dispersion
, flocculation, greasing
out, wastewater cleanup
air cut mud
English | Español
1. n. [Drilling Fluids,
Drilling]
A drilling fluid (or mud) that
has gas (air or natural gas)
bubbles in it, resulting in a
lower bulk, unpressurized
density compared with a mud
not cut by gas. The density of
gas-cut mud can be measured
accurately using a pressurized
mud
balance. Defoamerchemicals
added to the mud or a
mechanical vacuum
pump degasser can liberate
the trapped gas. The
derrickman periodically
measures mud density and
communicates the results to
the driller via an intercom,
typically reporting something
like "9.6 heavy," "10.4," or
"13.2 light," indicating more
than 9.6 pounds per gallon,
10.4 pounds per gallon, or
less than 13.2 pounds per
gallon, respectively. Each
tenth of a pound per gallon is
referred to as a "point"
of mud weight. Note that for
this lowaccuracymeasurement, no
direct mention of gas cut is
made. A gas cut is inferred
only if the mud returning to
the surface is significantly
less dense than it should be.
In the case of the mud
logger's measurement, "units"
of gas (having virtually no
absolute meaning) are
reported. For the mud logger's
measurement, a direct
indication of combustible
gases is made, with no
direct correlation to mud
weight.
Synonyms: gas-cut mud
See: derrickman, drilling
fluid
aliphatic compound
English | Español
1. n. [Drilling Fluids]
One of a group of organic
compounds of carbon (C) and
hydrogen (H) in which the
carbon atoms have linear,
branched chain (open), or
both types of structures.
Aliphatics, as they are
informally called, can be
divided into paraffinic
(saturated) and olefinic
(unsaturated) chain types. The
simplest aliphatic, paraffinic
hydrocarbon is methane, CH4.
The simplest
aliphatic, olefinic
hydrocarbon is ethylene,
C2H6. In drilling fluids,
particularly oil-base muds,
the amounts and types of
hydrocarbon in the mudcan
be an important parameter in
overall performance of the
mud.
Synonyms: acyclic
compound
See: aromatic
hydrocarbon, naphthenic
hydrocarbon, oil-base
mud, soap
alkaline
English | Español
1. adj. [Drilling Fluids]
Pertaining to an aqueous
solution, such as a water-base
drilling fluid, which has more
hydroxyl ions (OH-) than
hydrogen ions (H+) and pH
greater than 7.
Antonyms: acid
See: alkalinity, alkalinity
test, bland coring
fluid, cesium acetate, pH
alkalinity
English | Español
1. n. [Drilling Fluids]
A chemical property of an aqueous system that implies that there are more hydroxyl ions (OH-)
in the system, or a potential to produce more hydroxyl ions, than there are hydrogen ions (H+), or
potential to produce hydrogen ions.
Antonyms: acidity
Alternate Form: Pf, Pm
See: alkaline, alkalinity test, buffered mud, calcium carbonate, calcium hydroxide, carbon
dioxide, carbonate ion, caustic potash, caustic soda, formaldehyde, lime
mud, neutralization, pH, pH test, phenolphthalein, salt, siderite
alkalinity test
English | Español
1. n. [Drilling Fluids]
A measure of the total amount of hydroxyl ions in a solution as determined by titration with
standardized acid. This test is a well-known water-analysis procedure to estimate
hydroxyl, carbonate ion and bicarbonate ion concentrations. There are two pH endpoints, P and
M, in this titration, corresponding to phenolphthalein and methyl orange indicators. The "P"
endpoint is at pH 8.3 and the "M" endpoint is at pH 4.3. Each is reported in units of
cm3 acid/cm3 sample. For water samples and very simple mudfiltrates, P and M data indicate
OH-, HCO3- and CO3-2 concentrations, but an alkalinity test is unreliable for analyzing complex
mud filtrates. The API has established standards for conducting alkalinity tests.
amides
English | Español
1. n. [Drilling Fluids]
A group of organic chemicals
with the general formula
RCO-NH2 formed from
reactions of ammonia (NH3)
and a carboxylic acid, RCOOH+. "R" groups range from
hydrogen to various linear
and ring structures. Amides
and polyamides are
emulsifiers and surfactants,
many of which are made from
fatty acids.
amines
English | Español
1. n. [Drilling Fluids]
A group of organic chemicals
that are analogs of ammonia
(NH3), in which either one,
two or three hydrogen atoms
of ammonia are replaced by
organic radicals. General
formulas are: (1) primary
amines, RNH2, (2) secondary
amines, R1R2NH, (3) tertiary
amines, R1R2R3N and
quaternary amines,
R1R2R3 R4N+X (where X
represents an anion). Amines
are organic bases
(mildly alkaline) and react
with acids to form
nitrogenous, organic salts.
Amines made from fatty acids
are emulsifiers and oilwetting agents for oilfield
chemicals.
anaerobic
English | Español
1. adj. [Geology]
The condition of an
environment in which free
oxygen is lacking or absent.
Synonyms: anoxic
2. adj. [Geology]
A description of organisms
that can survive in the
absence of oxygen,
particularly bacteria.
3. adj. [Drilling Fluids]
Pertaining to systems,
reactions or life processes of
species, such as bacteria, in
which atmospheric oxygen is
not present or not required for
survival.
anhydrite
1. n. [Geology]
[CaSO4]
A member of the evaporite
group of minerals and the soft
rock comprising anhydrite
formed by precipitation
of calcium sulfate from
evaporation of seawater.
Anhydrite can also form
through the dehydration of
gypsum, another sulfate
mineral found in evaporites.
Anhydrite may occur as a
cap rock above salt domes.
aniline point test
English | Español
1. n. [Drilling Fluids]
A test to evaluate base oils
that are used in oil mud. The
test indicates if an oil is likely
to damage elastomers (rubber
compounds) that come in
contact with the oil. The
aniline point is called the
"aniline point temperature,"
which is the lowest
temperature (°F or °C) at
which equal volumes of
aniline (C6H5NH2) and the oil
form a single phase. The
aniline point (AP) correlates
roughly with the amount and
type of aromatic
hydrocarbons in an oil
sample. A low AP is
indicative of higher
aromatics, while a high AP is
indicative of lower aromatics
content. Diesel oil with AP
below 120°F [49°C] is
probably risky to use in oilbase mud. The API has
developed test procedures
that are the standard for the
industry.
anion
English | Español
1. n. [Drilling Fluids]
A negatively charged ion.
Clay surfaces, groups
on polymer chains, colloids
and other materials have
distinct, negatively charged
areas or ions. Anionic
characteristics affect
performance of additives and
contaminants in drilling
fluids, especially water muds,
in which clays and polymers
are used extensively.
Synonyms: anionic, water
mud
Antonyms: cation
anionic
English | Español
1. adj. [Drilling Fluids]
Related to negatively charged
ions. Clay surfaces, groups
on polymer chains, colloids
and other materials have
distinct, negatively charged
areas or ions. Anionic
characteristics affect
performance of additives and
contaminants in drilling
fluids, especially water muds,
in which clays and polymers
are used extensively.
Antonyms: cationic
anode
1. n. [Drilling Fluids]
The half of a battery that is positively charged and to which anions migrate by electrostatic attraction. Half of an
electrolytic corrosion cell in metal is called the "anode," from which metal dissolves, often leaving pits. The anode is
the part of a corrosion cell in which oxidation occurs.
antifoam
1. n. [Drilling Fluids]
A mud additive used to lower interfacial tension so that trapped gas will readily escape from mud. Mechanical
degassing equipment is commonly used along with defoamer. Octyl alcohol, aluminum stearate, various glycols,
silicones and sulfonated hydrocarbons are used as defoamers.
antifoam agent
A mud additive used to lower interfacial tension so that trapped gas will readily escape from mud. Mechanical
degassing equipment is commonly used along with defoamer. Octyl alcohol, aluminum stearate, various glycols,
silicones and sulfonated hydrocarbons are used as defoamers.
API
Abbreviation for American Petroleum Institute, a trade association founded in 1919 with offices in Washington, DC,
USA. The API is sponsored by the oil and gas industry and is recognized worldwide. Among its long-term endeavors
is the development of standardized testing procedures for drilling equipment, drilling fluids and cements, called API
Recommended Practices ("RPs"). The API licenses the use of its monogram (logo), monitors supplier quality
assurance methods and sets minimum standards for materials used in drilling and completion operations, called API
Specifications ("Specs"). The API works in conjunction with the International Organization of Standards (ISO).
API fluid loss test
. n. [Drilling Fluids]
A test to measure static filtration behavior of water mud at ambient (room) temperature and 100-psi
differential pressure, usually performed according to specifications set by API, using a static filter press. The filter
medium is filter paper with 7.1 sq. in. filtering area. A half-size cell is sometimes used, in which case the filtrate
volume is doubled.
API fluid-loss test
1. n. [Drilling Fluids]
A test to measure static filtration behavior of water mud at ambient (room) temperature and 100-psi
differential pressure, usually performed according to specifications set by API, using a static filter press. The filter
medium is filter paper with 7.1 sq. in. filtering area. A half-size cell is sometimes used, in which case the filtrate
volume is doubled.
API water
n. [Drilling Fluids]
The amount of mixing water specified in API Specification 10A for specification testing of cement to
meet API requirements. This amount is not intended to be a guide for mix water requirements in field applications.
aromatic content test
One of two quantitative analysis procedures for measuring aromatic content of base oils for use in oil mud as
proscribed by the API. Results of the two aromatic content tests may differ because of the way the two gaschromatography techniques separate and identify aromatics. The Institute of Petroleum (IP) instruments are more
widely available than the American Society for Testing and Materials (ASTM) instruments, and the Institute of
Petroleum method measures trace levels better than the more complex ASTM method.
apparent viscosity
. n. [Drilling Fluids]
The viscosity of a fluid measured at a given shear rate at a fixed temperature. In order for a viscosity measurement to
be meaningful, the shear rate must be stated or defined.
ASTM
1. n. [Drilling Fluids]
The designation of a standard developed by ASTM International. Until 2001, ASTM was an acronym for the American
Society for Testing and Materials, but the organization changed its name to ASTM International to reflect its global
scope as a forum for development of international voluntary consensus standards Some API procedures for drilling
fluids are similar to ASTM procedures.
attapulgite
1. n. [Drilling Fluids]
A needle-like clay mineral composed of magnesium-aluminum silicate. Major deposits occur naturally in Georgia,
USA. Attapulgite and sepiolite have similar structures and both can be used in saltwater mud to provide lowshear rate viscosity for lifting cuttings out of the annulus and for barite suspension. Attapulgite and sepiolite are
sometimes called "salt gel." Attapulgite has no capability to control the filtration properties of the mud. For use as an
oil mud additive, the clay is coated with quaternary amine, which makes it oil-dispersible and provides gel structure
but does not improve the filter cake, unlike organophilicbentonite clay.
bactericide
An additive that kills bacteria. Bactericides are commonly used in water muds containing natural starches and gums
that are especially vulnerable to bacterial attack. Bactericide choices are limited and care must be taken to find those
that are effective yet approved by governments and by company policy. Bactericides, also called biocides, can be
used to control sulfate-reducing bacteria, slime-forming bacteria, iron-oxidizing bacteria and bacteria that attacks
polymers in fracture and secondary recoveryfluids. In polymers, the degradation of the fluid is controlled, thus
avoiding the formation of a large biomass, which could plug the formation and reduce permeability.
barite
BaSO4] A dense sulfate mineral that can occur in a variety of rocks, including limestone and sandstone, with a range
of accessory minerals, such as quartz, chert, dolomite, calcite, siderite and metal sulfides. Barite is commonly used to
add weight to drilling fluid. Barite is of significance to petrophysicists because excess barite can require a correction
factor in some well logmeasurements.
base oil
1. n. [Drilling Fluids]
Refers to the continuous phase in oil-base drilling fluids. Oil-base drilling fluids are water-in-oil emulsions in which
water is the dispersed phase and oil is the dispersion, or continuous, phase. Oil-to-water ratios (OWR) in oil-base
drilling fluids vary from 65/35 to 95/5.
base slurry
A conventional cement slurry used as the cementitious component of a foamed cement slurry.
BBL or bbl
An abbreviation for oilfield barrel, a volume of 42 US gallons [0.16 m3].
Bc
The pumpability or consistency of a slurry, measured in Bearden units of consistency (Bc), a dimensionless quantity
with no direct conversion factor to more common units of viscosity
beneficiation
Chemical treatment or mechanical processes that improve a mineral or ore for its designed use. For
example, barite and bentonite clay minerals are beneficiated in order to help them meet certain specifications for use
in drilling fluids.
bentonite
A material composed of clay minerals, predominantly montmorillonite with minor amounts of other smectite group
minerals, commonly used in drilling mud. Bentonite swells considerably when exposed to water, making it ideal for
protecting formations from invasion by drilling fluids. Montmorillonite forms when basic rocks such as volcanic ash
in marine basins are altered.
bicarb
A compound containing the bicarbonate ion [HCOO-]. The term is commonly used to refer to the ion itself.
Bicarbonates are common constituents of drilling fluids. The ions are in equilibrium with carbonate and CO2 gas.
bichromate salt
A type of salt in which chromium atoms are in the plus-7 valence state, such as potassium dichromate, K2Cr2O7.
bioaccumulation
The concentration of a particular substance in a living organism, possibly with harmful effects.
biocide
An additive that kills bacteria. Bactericides are commonly used in water muds containing natural starches and gums
that are especially vulnerable to bacterial attack. Bactericide choices are limited and care must be taken to find those
that are effective yet approved by governments and by company policy. Bactericides, also called biocides
bioconcentration
The concentration of a particular substance in a living organism, possibly with harmful effects.
biopolymer
A polymer produced by a strain of bacteria. The most common type, used in drilling and completion operations, is
a polysaccharide biopolymer known as XC polymer.
black list
List of products considered unsuitable by the Oslo and Paris Commission (OSPAR) for discharge, including mercury,
cadmium and 'persistent oils and hydrocarbons of a petroleum origin.'
Blaine fineness
1. n. [Drilling Fluids]
The particle size or fineness of a cement in cm2/g or m2/kg, usually determined from air permeability tests using a
device known as a Blaine permeameter. Fineness affects the hydration rate (setting) and the requirements for the
amounts of water, retarderand dispersant.
BOD
The amount of oxygen consumed by biodegradation processes during a standardized test. The test usually involves
degradation of organic matter in a discarded waste or an effluent.
bomb
Slang term for a type of pressure vessel.
bond log
A log that uses the variations in amplitude of an acoustic signal traveling down the casing wall between a transmitter
and receiver to determine the quality of cement bond on the exterior casing wall.
bottomhole circulating temperature
The temperature of the circulating fluid (air, mud, cement or water) at the bottom of the wellbore after several hours
of circulation. This temperature is lower than the bottomhole static temperature.
bottomhole static temperature
The temperature of the undisturbed formation at the final depth in a well.
bottoms up mud sample
A sample of mud from the deepest or current drilling depth of a well. The term refers particularly to a mud sample that
has experienced stagnant conditions at the bottom of the hole, including the temperature, pressure and other
conditions at that depth.
breaker
A chemical that reduces the viscosity of a fluid by breaking long-chain molecules into shorter segments. Drilling fluids
are commonly emulsified or contain long-chain molecules that have sufficient viscosity to carry cuttings to surface.
After the drilling fluid has done its job, a breaker may be added to reduce the viscosity of the fluid by breaking down
the long chain molecules into shorter molecules. A surfactant may be added to an emulsion to reduce its viscosity.
bridging agent
Solids added to a drilling fluid to bridge across the pore throat or fractures of an exposed rock thereby building a filter
cake to prevent loss of whole mud or excessive filtrate. Bridging materials are commonly used in drilling fluids and
in lost circulationtreatments.
bridging material
Solids added to a drilling fluid to bridge across the pore throat or fractures of an exposed rock thereby building a filter
cake to prevent loss of whole mud or excessive filtrate.
brine
Water containing more dissolved inorganic salt than typical seawater.
bromide brine
An aqueous solution of sodium, calcium or zinc bromide salt or mixtures of these salts. These dense aqueous
solutions are used for well completion and workover purposes.
bromocresol green
An indicator used in place of methyl orange in alkalinity tests. It is green at pH values over 4.3, but yellow when pH is
less than 4.3.
Brookfield viscometer
A cone-and-plate rheometer designed to measure viscosity of non-Newtonian fluids at low shear rates and with
more accuracythan is attainable with a 6-speed, direct-indicating viscometer.
buffer
A chemical used to adjust and control the pH of stimulation fluids.
cake
The residue deposited on a permeable medium when a slurry, such as a drilling fluid, is forced against the medium
under a pressure. Filtrate is the liquid that passes through the medium, leaving the cake on the medium. Drilling
muds are tested to determine filtration rate and filter-cake properties.
cathode
The negative terminal of an electrolytic cell or battery.
capillary tube viscometer
An instrument for measuring the viscosity of a fluid by passing the fluid at a known pressure
gradient or velocity through a length of tubing of known diameter. The viscosity of base oils for oil muds, which are
Newtonian fluids, is measured using a glass capillary tube in a thermostatic bath, when performed according
to API procedures.
cavings
Pieces of rock that came from the wellbore but that were not removed directly by the action of the drill bit. Cavings
can be splinters, shards, chunks and various shapes of rock, usually spalling from shale sections that have become
unstable. T
caustic soda
The common name for sodium hydroxide [NaOH]. Caustic soda is used in most water-base muds to increase and
maintain pHand alkalinity.
caustic potash
The common name for potassium hydroxide [KOH]. Caustic potash is used in potassium-based water muds to
increase pH and alkalinity and to help maintain the K+ ion concentration.
CEC
Quantity of positively charged ions (cations) that a clay mineral (or similar material) can accommodate on its negative
charged surface, expressed as milliequivalents per 100 grams. CEC of solids in drilling muds is measured on a
whole mud sample by a methylene blue capacity (MBC) test,
centipoise
A unit of measurement for viscosity equivalent to one-hundredth of a poise and symbolized by cP. Viscosity is the
ratio of shear stress to shear rate, giving the traditional unit of dyne-sec/cm2 for Poise. In metric (SI) units, one cP is
one millipascal-second.
centrifuge
An item of solids-removal equipment that removes fine and ultrafine solids. It consists of a conical drum that rotates
at 2000 to 4000 rpm. Drilling fluid is fed into one end and the separated solids are moved up the bowl by a rotating
scroll to exit at the other end. Centrifuges generally have limited processing capacity (50 to 250 gpm) but are useful
for processing weighted drilling fluids and can remove finer solids than can a hydrocyclone or shaker screens.
2. n. [Formation Evaluation]
A rapidly rotating flywheel on a vertical axle to whose rim is attached a series of tubes at one end, the other end
being free to tilt upwards and outwards. At high speeds, the centrifugal force in the tubes is far greater than gravity.
The centrifuge is used to expel fluids from core samples,
chemical barrel
The chemical barrel is used to slowly dispense various types of liquids into the active mud system. It has traditionally
been used to add caustic (NaOH or KOH) solution at a slow and steady rate in order to maintain a
uniform pH throughout a circulating mud system.
Chenevert Method
The name given by API to the electrohygrometer method for testing oil mud and cuttings samples for water-phase
activity,
chloride test
A titration procedure standardized by the API to quantitatively determine Cl- (chloride ion) concentration by using
silver nitrate as titrant with potassium chromate as the endpoint indicator.
chromate salt
A type of salt in which chromium atoms are in the plus-6 valence state, such as potassium chromate, K2CrO4.
chromic salt
A salt of chromium in which chromium atoms are in the plus-3 valence state, such as chromic chloride,
CrCl3.
CMS
A natural starch derivative. CMS is used primarily for fluid-loss control in drilling muds, drillin, completion and workover fluids
CMHEC
cellulose polymer that contains anionic carboxymethyl and nonionic hydroxyethyl groups added by ether linkages to
the OHs on the cellulose backbone. This polymer has seen limited use in drilling mud, but more use in brines
and completion fluids.
clear brine
Water containing more dissolved inorganic salt than typical seawater.
Saline liquid usually used in completion operations and, increasingly, when penetrating a pay zone.
A general term that refers to various salts and salt mixtures dissolved in an aqueous solution
clay
A group of rock-forming, hydrous aluminum silicate minerals that are platy in structure and can form by the
alteration of silicate minerals like feldspar and amphibole. A large family of complex minerals containing the
elements magnesium, aluminum, silicon and oxygen (magnesium, aluminum silicates) combined in a sheetlike structure.
citric acid
An organic acid, properly called 2-Hydroxy-1,2,3-propanetricarboxylic acid, with formula C6H8O7. Citric
acid is used to reduce the pH of drilling fluids and hence for treatment of cement contamination.
clathrate
Compounds or complex ions that are formed by the union of water with other substances. A crystalline solid
consisting of water with gas molecules in an ice-like cage structure.
COD
The amount of oxygen needed to oxidize reactive chemicals in a water system, typically determined by a
standardized test procedure. COD is used to estimate the amount of a pollutant in an effluent.
contact time
The elapsed time required for a specific fluid to pass a designated depth or point in the annulus during
pumping operations. Contact time is normally used as a design criterion for mud removal in turbulent flow.
colloid
A finely divided, solid material, which when dispersed in a liquid medium, scatters a light beam and does not
settle by gravity
CWA
Abbreviation for "Clean Water Act," a law passed by the US Congress to control the discharge of
contaminants, particularly oil, into the waters of the US.
cuttings
Small pieces of rock that break away due to the action of the bit teeth.
curing
The aging of cement under specific temperature and pressure conditions.
creaming
The separation of phases of an emulsion with the lighter phase on top and denser phase on bottom
coring fluid
A specially designed fluid that is used for cutting cores with a core barrel and core bit.