| cable-tool
drilling |
a drilling method in which the
hole is drilled by dropping a sharply pointed bit on bottom. The bit is attached to a
cable, and the cable is repeatedly dropped as the hole is drilled. |
| cage |
the part of a pump valve
which holds the ball to limit its movement. |
| cage wrench |
a special wrench designed for use
in connecting the cage of a sucker rod pump to the sucker rod string. |
| caisson |
1. one of several columns made of
steel or concrete, which serves as the foundation for a rigid offshore platform rig, such
as the concrete gravity platform rig. 2. a steel or
concrete chamber that surrounds equipment below the waterline of an arctic submersible
rig, thereby protecting the equipment from damage by moving ice. |
| caisson-type platform rig |
a rigid offshore drilling platform
that stands on steel caissons and is used to drill development wells. The caissons
are firmly affixed to the seafloor, and the drilling and production decks are laid on top
of them. The platform is used in certain arctic waters, where the caissons are
needed to protect equipment from moving ice. See platform
rig. |
| cake |
see filter
cake. |
| cake
consistency |
the character or state of the
drilling mud filter cake. From API RP 13B: notations such as "hard,"
"soft," "tough," rubbery," and "firm" may be used to
convey some idea of cake consistency. |
| cake
thickness |
the thickness of drilling mud
filter 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 water hardness. Calcium is also a component of lime, gypsum, and limestone. |
| calcium
carbonate |
a chemical combination of calcium,
carbon, and oxygen. It is the main constituent of limestone. It forms a tenacious
scale in water-handling facilities and is a cause of water hardness. |
| calcium
chloride |
a moisture-absorbing chemical
compound, or desiccant used to accelerate setting times in cement and as a drying agent. |
| calcium
contamination |
dissolved calcium ions in
sufficient concentration to impart undesirable properties, such as flocculation, reduction
in yield of bentonite, and increased fluid loss, in a drilling fluid. See also calcium carbonate, calcium sulfate, gypsum. |
| calcium
hydroxide |
the active ingredient of slaked
(hydrated) lime, and the main constituent in cement (when wet). Referred to as
"lime" in field terminology. |
| calcium
sulfate |
a chemical compound of calcium,
sulfur, and oxygen. Although sometimes considered a contaminant of drilling fluids, it may
at times be added to them to produce certain properties. Like calcium carbonate it
forms scales in water-handling facilities, which may be hard to remove. See gypsum. |
| calcium-treated
mud |
a freshwater drilling mud using
calcium oxide (lime) or calcium sulfate (gypsum) to retard the hydrating qualities of
shale and clay formation, thus facilitating drilling. Calcium-treated muds resist
scale and any anhydrite contamination but may require further treatment to prevent
gelation (solidifcation) under the high temperatures of deep wells. |
| caliper |
an instrument with two legs or
jaws that can be adjusted for measuring linear dimensions, thicknesses, or diameters. |
| caliper log |
a record showing variations in
wellbore diameter by depth, indicating undue enlargement due to caving in, washing, or
other causes. The caliper log also reveals corrosion, scaling, or pitting inside
tubular goods. |
| Cameron
gauge |
generically, a pressure gauge
usually used in lines or manifolds. Many companies make pressure gauges. Cameron,
now Cooper Oil Tools, makes many types of gauges. |
| cantilever |
a beam or beams that project
outward from a structure and are supported only at one end. |
| cantilevered
jackup |
a jackup drilling unit in which
the drilling rig is mounted on two cantilevers that extend outward from the barge hull of
the unit. The cantilevers are supported only at the barge end. |
| cap a well |
to control a blowout by placing a
very strong valve on the wellhead. See blowout. |
| caprock |
1.a disk-like plate of anhydrite,
gypsum, limestone, or sulfur overlying most salt domes in the Gulf Coast region. 2. impermeable rock overlying an oil or gas reservoir that tends to
prevent migration of oil or gas out of the reservoir. |
| carboxymethyl
cellulose |
a non-fermenting cellulose product
used in drilling fluids to combat contamination from anhydrite (gypsum) and to lower the
water loss of the mud. |
| carrier rig |
a large, specially designed,
self-propelled workover rig that a person drives directly to the well site. Power
from a carrier rig's hoist engine or engines also propels the rig on the road. While
a carrier rig is primarily intended to perform workovers, it can also be used to drill
relatively shallow wells. A carrier rig may be a back-in type or a drive-in type.
See back-in unit, drive-in unit. |
| cased |
pertaining to a wellbore in which
casing has been run and cemented. See casing. |
| cased hole |
a wellbore in which casing has
been run. |
| casing |
steel pipe placed in an oil or gas
well as drilling progresses to prevent the wall of the hole from caving in during
drilling, to prevent seepage of fluids, and to provide a means of extracting petroleum if
the well is productive. |
| casing
burst pressure |
the amount of pressure that, when
applied inside a string of casing, causes the wall of the casing to fail. This
pressure is critically important when a gas kick is being circulated out, because gas on
the way to the surface expands and exerts more pressure than it exerted at the bottom of
the well. |
| casing
centralizer |
a device secured around the casing
at the regular intervals to center it in the hole. Casing that is centralized allows
a more uniform cement sheath to form around the pipe. |
| casing
coupling |
a tubular section of pipe that is
threaded inside and used to connect two joints of casing. |
| casing gun |
a perforating gun run in on the
casing string. |
| casing
hanger |
a circular device with a
frictional gripping arrangement of slips and packing rings used to suspend casing from a
casinghead in a well |
| casing
pressure |
gas pressure built up between the
casing and tubing. |
| casinghead |
a heavy, flanged steel fitting
connected to the first string of casing. It provides a housing for slips and packing
assemblies, allows suspension of intermediate and production strings of casing, and
supplies the means for the annulus to be sealed off. Also called a spool. |
| casinghead
gas |
(oil well gas) is associated and
dissolved gas produced along with crude oil from oil completions. |
| casinghead
gasoline |
(obsolete) natural gasoline. |
| casing
overshot |
see casing-patch
tool |
| casing pack |
a means of cementing casing in a
well so that the casing may, if necessary, be retrieved with minimum difficulty. A
special mud, usually an oil mud, is placed in the well ahead of the cement after the
casing has been set. Non-solidifying mud is used so that it does not bind or stick
to the casing in the hole in the area above the cement. Since the mud does not gel
for a long time, the casing can be cut above the cemented section and retrieved.
Casing packs are used in wells of doubtful or limited production to permit reuse of
valuable lengths of casing. |
| casing-patch
tool |
a special tool with a rubber
packer or lead seal that is used to repair casing. When casing is damaged downhole,
a cut is made below the damaged casing, the damaged casing and the casing above it are
pulled from the well, and the damaged casing is removed from the casing string. The
tool is made up and lowered into the well on the casing until it engages the top of the
casing that remains in the well, and a rubber packer or lead seal in the tool forms a seal
with the casing that is in the well. The casing-patch tool is an over-shot-like
device and is sometimes called a casing overshot. |
| casing
pressure |
the pressure in a well between the
casing and the tubing or the casing and the drill pipe. |
| casing
protector |
a short threaded nipple screwed
into the open end of the coupling and over the threaded end of casing to protect the
threads from dirt accumulation and damage. It is made of steel or plastic.
Also called thread protector. |
| casing
roller |
a tool composed of a mandrel on
which are mounted several heavy-duty rollers with eccentric roll surfaces. It is
used to restore buckled, collapsed, or dented casing in a well to normal diameter and
roundness. Made up on tubing or drill pipe and run into the well to the depth of the
deformed casing, the tool is rotated slowly, allowing the rollers to contact all sides of
the casing and restore it to roughly its original condition. |
| casing
scraper |
blade tool used to scrape away
junk or debris from inside casing; run on pipe or tubing. |
| casing
seal receptacle |
a casing sub containing a seal
bore and a left-handed thread, run as a crossover between casing sizes, to provide a
tubing anchor. |
| casing seat |
the location of the bottom of a
string of casing that is cemented in a well. Typically, a casing shoe is made up on
the end of the casing at this point. |
| casing
seal test |
a procedure whereby the formation
immediately below the casing shoe is subjected to a pressure equal to the pressure
expected to be exerted later by a higher drilling glut density or by the sum of a higher
drilling fluid density and back-pressure created by a kick. |
| casing shoe |
see guide
shoe |
| casing
string |
the entire length of all the
joints of casing run in a well. Most casing joints are manufactured to
specifications established by API, although non-API specification casing is available for
special situations. Casing manufactured to API specifications is available in three
length ranges. A joint of range 1 casing is 16 to 25 feet long; a joint of range 2
casing is 25 to 34 feet long; and a joint of range 3 casing is 34 to 48 feet long.
The outside diameter of a joint of API casing ranges from 4 1/2 to 20 inches. |
| casing
tongs |
large wrench used for turning when
making up or breaking out casing. See tongs. |
| cat |
a crawler-type tractor. |
| cat walk |
the narrow walkway on top of a
tank battery. |
| catcher |
a device fitted into a junk basket
and acting as a trap door to retain the junk |
| catch
samples |
to obtain cuttings for geological
information as formations are penetrated by the bit. The samples are obtained from
drilling fluid as it emerges from the wellbore or, in cable-tool drilling, from the
bailer. Cuttings are carefully washed until they are free of foreign matter, dried,
and labeled to indicate the depth at which they were obtained. |
| cathead |
a spool-shaped attachment on a
winch around which rope is wound for hoisting and pulling. |
| catline |
a hoisting or pulling line
operated from a cathead. |
| catwalk |
1. the ramp at the side of the
drilling rig where pipe is laid to be lifted to the derrick floor by the catline or by an
air hoist. 2. any elevated walkway |
| caustic
soda |
sodium hydroxide. Used to maintain
an alkaline pH in drilling mud and in petroleum fractions. |
| cave-in |
the collapse of the walls of the
wellbore. |
| cavernous
formation |
a rock formation that contains
large open spaces, usually resulting from the dissolving of soluble substances by
formation waters that may still be present. See vug. |
| caving |
collapsing of the walls of the
wellbore. Also called sloughing. |
| cavitation |
the formation and collapse of
vapor- or gas-filled cavities that result from a sudden decrease and increase of pressure.
Cavitation can cause mechanical damage to adjacent surfaces in meters, valves,
pumps, and pipes at locations where flowing liquid encounters a restriction or change in
direction. |
| CBHT |
abbreviation: circulating
bottomhole temperature |
| CBL |
abbreviation: cement bond
long. |
| cc |
abbreviation: cubic
centimeter |
| CCL |
casing collar log |
| cellar |
a hole dug, usually before
drilling of a well, to allow working space for the casinghead equipment. |
| cement |
a powder, consisting of alumina,
silica, lime, and other substances that hardens when mixed with water. Extensively
used in the oil industry to bond casing to the walls of the wellbore. |
| cement
bond survey |
an acoustic survey or sonic
logging method that records the quality or hardness of the cement used in the annulus to
bond the casing and the formation. Casing that is well bonded to the formation
transmits an acoustic signal quickly; poorly bonded casing transmits a signal slowly.
See acoustic survey, acoustic well logging. |
| cementer |
a generic term used to describe a
retrievable service squeeze tool; used in remedial cementing. |
| cementing |
the application of a liquid slurry
of cement and water to various points inside or outside the casing. See primary cementing, secondary cementing. |
| cementing
head |
an accessory attached to the top
of the casing to facilitate cementing of the casing. It has passages for cement
slurry and retain chambers for cementing wiper plugs. |
| cementing
materials |
a slurry of portland cement and
water and sometimes one or more additives that affect either the density of the mixture or
its setting time. The portland cement used may be high early strength common
(standard), or slow setting. Additives include accelerators (such as calcium
chloride), retarders (such as gypsum), weighting materials (such as barium sulfate),
lightweight additives (such as bentonite), or a variety of lost circulation materials
(such as mica flakes). |
| cement plug |
a portion of cement placed at some
point in the wellbore to seal it. See cementing. |
| cement pulsation |
cement
pulsation entails the use of specialized surface equipment to apply
low-intensity pressure pulses to the annulus immediately following the
cement pumping operation. The pulses serve to break the gel strength of
the cement during the cement setting process. Gel strength development
causes a reduction of the hydrostatic pressure transmitted through the
annulus. By breaking the gel strength, hydrostatic pressure is
maintained on the column until the cement has built sufficient strength
to prevent the potential influx of reservoir fluids through the cement
matrix. |
| cement
retainer |
a tool set temporarily in the
casing or well to prevent the passage of cement, thereby forcing it to follow another
designated path. It is used in squeeze cementing and other remedial cementing jobs. |
| centipoise |
one-hundredth of a poise; a
measure of a fluid's viscosity, or resistance to flow. |
| centralizer |
see casing
centralizer |
| centrifugal
pump |
a pump with an impeller or rotor,
an impeller shaft, and a casing, which discharges fluid by centrifugal force. |
| centrifuge |
a shake-out or grind-out machine.
Samples of oil are placed in the machine and whirled at high speed to settle out sediment. |
| certs |
certifications of materials on
physical and chemistry properties. |
| chain drive |
a mechanical drive using a driving
chain and chain gears to transmit power. Power transmissions use a roller chain, in
which each link is made of side bars, transverse pins, and rollers on the pins. A
double roller chain is made of two connected rows or links, a triple roller chain of
three, and so forth. |
| chain tongs |
a hand tool consisting of a handle
and chain that resembles the chain on a bicycle. In general, chain tongs are used
for turning pipe or fittings of a diameter larger than that which a pipe wrench would fit.
The chain is looped and tightened around the pipe or fitting, and the handle is
used to turn the tool so that the pipe or fitting can be tightened or loosened. |
| change
house |
a small building, or doghouse, in
which members of a drilling rig or roustabout crew change clothes, store personal belongs,
and so on. |
| change rams |
to take rams out of a blowout
preventer and replace them with rams of a different size or type. When the size of a
drill pipe is changed, the size of the pipe rams must be changed to ensure that they seal
around the pipe when closed (unless variable-bore pipe rams are in use). |
| chase
threads |
to straighten and clean threads of
any king. |
| cheater |
a length of pipe used to increase. |
| check valve |
a valve that permits flow in one
direction only. if the gas or liquid starts to reverse, the valve automatically
closes, preventing reverse movement. Commonly referred to as a one-way valve. |
| chemical
barrel |
a container in which various
chemicals are mixed prior to addition to drilling fluid. |
| chemical
cutoff |
a method of severing steel pipe in
a well by applying high-pressure jets of a very corrosive substance against the wall of
the pipe. The resulting cut is very smooth. |
| chemicals |
in drilling-fluid terminology, a
chemical is any material that produces changes in the viscosity, yield point, gel
strength, fluid loss, and surface tension. |
| chicksan |
flexible coupling used in
high-pressure lines. |
| chisel
tongs |
pipe tongs that grip the pipe with
a chisel-like insert in the jaw of the wrench. |
| choke |
a device inserted in a flow line
to regulate the rate of flow. |
| choke bean |
a device placed in a choke line
that regulates the flow through the choke. Flow depends on the size of the opening
in the bean; the larger the opening, the greater the flow. |
| choke
flow line |
an extension from the blowout
preventer assembly used to direct control the flow of well fluids from the annulus to the
choke. |
| choke line |
a pipe attached to the blowout
preventer stack out of which kick fluids and mud can be pumped to the choke manifold when
a blowout preventer is closed in on a kick. |
| choke
manifold |
an arrangement of piping and
special valves, called chokes. In drilling, mud is circulated through a choke
manifold when the blowout preventers are closed. In well testing, a choke manifold
attached to the wellhead allows flow and pressure control for test components downstream. |
| choke
pressure |
see back-pressure |
| Christmas
tree |
the control valves, pressure
gauges, and chokes assembled at the top of a well to control the flow of oil and gas after
the well has been drilled and completed. |
| chromate |
a compound in which chromium has a
valence of 6. Chromate may be added to drilling fluids either directly or as a constituent
of chrome lignites or chrome lignosulfonates. In certain areas, chromate is widely
used as a corrosion inhibitor, often in conjunction with lime. |
| chrome
lignite |
mined lignite, usually leonardite,
to which chromate has been added or has reacted. The lignite can also be causticized
with either sodium or potassium hydroxide. |
| circulate |
to pass from one point throughout
a system and back to the starting point. For example, drilling fluid is circulated
out of the suction pit, down the drill pipe and drill collars, out the bit, up the
annulus, and back to the pits while drilling proceeds. |
| circulate-and-weight method |
see concurrent
method |
| circulating
components |
the equipment included in the
drilling fluid circulating system of a rotary rig. Basically, the components consist
of the mud pump, rotary hose, swivel, drill stem, bit, and mud return line. |
| circulating
head |
an accessory attached o the top of
the drill pipe or tubing to form a connection with the mud system to permit circulation of
the drilling mud. In some cases, it is also a rotating head. |
| circulating
pressure |
the pressure generated by the mud
pumps and exerted on the drill stem |
| circulating
rate |
volume flow rate of circulating
drilling fluid expressed in gallons or barrels per minute |
| circulation |
movement of drilling fluid from
mud pits, down drill stem, up annulus, and back to mud pits. |
| circulation
squeeze |
a variation of squeeze cementing
for wells with two producing zones in which (1) the upper fluid sand is perforated; (2)
tubing is run with a packer, and the packer is set between the two perforated intervals;
(3) water is circulated between the two zones to remove as much mud as possible from the
channel; (4) cement is pumped through the channel and circulated; (5) the packer is
released and picked up above the upper perforation, a low squeeze pressure is applied, and
the excess cement is circulated out. The process is applicable where there is
communication behind the pipe between the two producing zones because of channeling of the
primary cement or where there is essentially no cement in the annulus. |
| circulation
valve |
an accessory employed above a
packer, to permit annulus-to-tubing circulation or vice versa. |
| clabbered |
(slang) commonly used to describe
moderate to severe flocculation of mud due to various contaminants. |
| clay |
1. a term used for particles
smaller than 1/256 millimeter (4 microns) in size, regardless of mineral composition.
2. a group of hydrous aluminum silicate
minerals (clay minerals)
3. a sediment of fine clastics. |
| clay
extender |
any of several substances--usually
organic compounds of high molecular weight--that, when added in low concentrations to a
bentonite or to certain other clay slurries, will increase the viscosity of the system.
See low-solids mud. |
| clean out |
to remove sand, scale, and other
deposits from the producing section of the well to restore or increase production. |
| CLFP |
abbreviation: choke-line
friction pressure. |
| clip |
a U-bolt or similar device used to
fasten parts of a wire cable together. |
| close in |
1. to shut in a well temporarily
that is capable of producing oil or gas. 2. to dose
the blowout preventers on a well to control a kick. The blowout preventers close off
the annulus so that pressure from below cannot flow to the surface. |
| close
nipple |
a very short piece of pipe having
threads over its entire length. |
| closed-in |
a well capable of producing oil or
gas, but temporarily shut in. |
| closing
ratio |
the ratio between the pressure in
the hole and the operating-piston pressure needed to close the rams of a blowout
preventer. |
| closing
unit |
the assembly of pumps, valves,
lines, accumulators, and other items necessary to open and close the blowout preventer
equipment. |
| closing-up
pump |
an electric or hydraulic pump on
an accumulator that pumps hydraulic fluid under high pressure to the blowout preventers so
that they may be closed or opened. |
| CMC |
abbreviation: see sodium
carboxymethyl cellulose, coagulation, flocculation. |
| coalescence |
1. the change from a liquid to a
thickened, curd-like state by chemical reaction. 2. the combining of globules in an emulsion caused by molecular attraction of the
surfaces. |
| cohesion |
the attractive force between the
same kinds of molecules (i.e., the force that holds the molecules of a substance together) |
| coiled
tubing |
see reeled tubing |
| coiled-tubing
workover |
a workover performed with a
continuous steel tube, normally 3/4 inch to 1 inch outside diameter, which is run into the
well in one piece inside the normal tubing. Lengths of the tubing up to 16,000 feet
are stored on the surface on a reel in a manner similar to that used for wireline. The
unit is rigged up over the wellhead. The tubing is injected through a control head
that seals off the tubing and makes a pressure-tight connection. A unique feature of
the unit is that it allows continuous circulation while it is being lowered into the hole. |
| collar |
a pipe coupling threaded on the
inside. |
| collar
locator |
a logging device used to determine
accurately the depth of a well; the log measures and records the depth of each casing
collar, or coupling, in a well. Since the length of each joint of casing is written
down, along with the number of joints of casing that were put into the well, knowing the
number and depth of the collars allows an accurate measure of well depth |
| collet |
a finger-like device used to lock or
position certain tool components by manipulating the tubing string or downhole tool |
| colloid |
1. a substance whose particles are
so fine that they will not settle out of suspension or solution and cannot be seen under
an ordinary microscope. 2. the mixture of a
colloid and the liquid, gaseous, or solid medium in which it is dispersed. |
| colloidal |
pertaining to a colloid, i.e.,
involving particles so minute (less than 2 microns) that they are not visible through
optical microscopes. Bentonite is an example of a colloidal day. |
| colloidal
composition |
a colloidal suspension containing
one or more colloidal constituents |
| colloidal
suspension |
finely divided particles of
ultramicroscopic size swimming in a liquid. |
| come-along |
a stretching or tightening device
that crawls along a length of chain. |
| come
out of the hole |
to pull the drill stem out of the
wellbore to change the bit, to change from a core barrel to the bit, to run electric logs,
to prepare for a drill stem test, to run casing, and so on. Also called trip
out. |
| commercial
butane |
a liquefied hydrocarbon consisting
chiefly of butane to butylenes and conforming to the GPA specification for commercial
butane defined in GPA Publication 2140. |
| commercial
production |
oil and gas production of
sufficient quantity to justify keeping a well in production. |
| company
representative |
an employee of an operating
company whose job is to represent the company's interests at the drilling location. |
| complete
a well |
to finish work on a well and bring
it to productive status. See well
completion. |
| completion |
refers to the installation of
permanent equipment for the production of oil or gas. |
| completion
fluid |
low-solids fluid or drilling mud
used when a well is being completed. it is selected not only for its ability to
control formation pressure, but also for the properties that minimize formation damage. |
| compressability |
the change in volume per unit of
volume of a liquid caused by a unit change in pressure at constant temperature |
| compressability
factor |
the ratio of the actual volume of
gas at a given temperature and pressure to the volume of gas when calculated by the ideal
gas law. |
| computer |
1. a device capable of solving
problems by accepting data, performing prescribed operations on the data, and supplying
the results of these operations. Various types of computers are calculators, digital
computers, and analog computers. 2. in
information processing, usually an automatic stored program computer. |
| computer
control |
a system whereby the end devices
in the field (switches, valves, gauges, alarms, etc.) are controlled by a program placed
in the computer. |
| computer
program |
a plan or routine for solving a
problem on a computer. |
| concentric
piston |
tubing pressure acting on the net
piston area and causing a force to be exerted on a mandrel. |
| concentric tubing workover |
a workover performed with a
small-diameter tubing work string inside the normal tubing. Equipment needed is
essentially the same as that for a conventional workover except that it is smaller and
lighter. |
| concrete gravity platform rig |
a rigid offshore drilling platform
built of steel-reinforced concrete and used to drill development wells. The platform
is floated to the drilling site in a vertical position, and at the site tall caissons that
serve as the foundation of the platform are flooded so that the platform submerges and
comes to rest on bottom. Because of the enormous weight of the platform, the force
of gravity alone keeps it in place. See platform
rig. |
| concurrent
method |
a method for killing well pressure
in which circulation is commenced immediately and mud weight is brought up in steps, or
increments, usually a point at a time. Also called circulate-and-weight method. |
| condensate |
hydrocarbons which are in the
gaseous state under reservoir conditions but which become liquid either in passage up the
hole or at the surface. |
| conductor
casing |
generally, the first string of
casing in a well. It may be lowered into a hole drilled into the formations near the
surface and cemented in place; or it may be driven into the ground by a special pile drive
(in such cases, it is sometimes called drive pipe); or it may be jetted into place in
offshore locations. Its purpose is to prevent the soft formations near the surface
from caving in and to conduct drilling mud from the bottom of the hole to the surface when
drilling starts. Also called conductor pipe. |
| conductor
pipe |
a short string of large-diameter
casing used to keep the wellbore open and to provide a means of conveying the upflowing
drilling fluid from the wellbore to the mud pit. |
| connate
water |
water inherent to the producing
formation; or fossil sea water trapped in the pore spaces of sediments during their
deposition. |
| connection |
the joining of two length of pipe. |
| consistometer |
a thickening-time tester having a
stirring apparatus to measure the relative thickening time for mud or cement slurries
under predetermined temperatures and pressures. See API-RP 10B. |
| conductivity |
1. the ability to transmit or
convey (as heat or electricity). 2. an electrical
logging measurement obtained from an induction survey, in which eddy currents produced by
an alternating magnetic field induce in a receiver coil a voltage proportionate to the
ability of the formation to conduct electricity. |
| conductor
casing |
generally, the first string of
casing in a well. It may be lowered into a hole drilled into the formations near the
surface and cemented in place; it may be driven into the ground by a special pile driver
(in such cases, it is sometimes called drive pipe); or it may be jetted into place in
offshore locations. Its purpose is to prevent the soft formations near the surface
from caving in and to conduct drilling mud from the bottom of the hole to the surface when
drilling starts. Also called conductor pipe. |
| conductor
line |
a small-diameter conductive line
used in electric wireline operations, such as electric well logging and perforating, in
which the transmission of electrical current is required. Compare wireline. |
| conductor
pipe |
1. see conductor
casing 2. a boot, or flume. |
| cone |
a component of a downhole tool,
such as a packer, used to wedge slips into the casing wall. |
| coning |
see water coning. |
| connate
water |
water retained in the pore spaces,
or interstices, of a formation from the time the formation was created. |
| connection
gas |
the relatively small amount of gas
that enters a well when the mud pump is stopped for a connection to be made. Since
bottomhole pressure decreases when the pump is stopped, gas may enter the well. |
| consistency |
the cohesion of the individual
particles of a given material (i.e., its ability to deform or its resistance to flow). |
| constant choke-pressure method |
a method of killing a well that
has kicked, in which the choke size is adjusted to maintain a constant casing pressure.
This method does not work unless the kick is all or nearly all salt water. if
the kick is gas, this method will not maintain a constant bottomhole pressure, because gas
expands as it rises in the annulus. In any case, it is not a recommended
well-control procedure. |
| constant pit-level method |
a method of killing a well in
which the mud level in the pits is held constant while the choke size is reduced and the
pump speed slowed. It is not effective, and therefore, is not recommended, because
casing pressure increases to the point at which the formation fractures or casing
ruptures, and control of the well is lost. |
| contact
area |
gas-oil or oil-water interface in
a reservoir. |
| contamination |
the presence in a drilling fluid
of any foreign material that may tend to produce detrimental properties of the drilling
fluid. |
| continuous
phase |
the liquid in which solids are
suspended or droplets of another liquid are dispersed; sometimes called the external
phase. In a water-in-oil emulsion, oil is the continuous phase. |
| contour map |
a map constructed with continuous
lines connecting points of equal value, such as elevation, formation thickness, and rock
porosity |
| control
head |
an extension of a retrievable
tool, i.e., a retrievable bridge plug, used to set and release the tool. |
| control
panel |
part of a computer system that
contains manual controls--switches and devices to start, stop, measure, monitor or signal
what is taking place. |
| controlled
aggregation |
a condition in which clay
platelets remain stacked by a polyvalent cation, such as calcium, and are deflocculated by
use of a thinner. |
| controlled directional drilling |
See directional drilling. |
| control
line |
a small hydraulic line used to
communicate fluid from the surface to a downhole tool, such as a subsurface safety valve. |
| conventional
completion |
a method for completing a well in
which tubing is set inside 4-1/2-inch or larger casing. |
| conventional
gravel pack |
a type of gravel pack where the
wells production packer is removed and a service packer is run in with the gravel pack
assembly. After packing, the service tool is retrieved and the production packer
rerun. |
| conventional
mud |
a drilling fluid containing
essentially clay and water; no special or expensive chemicals or conditioners are added. |
| copolymer |
a substance formed when two or
more substances polymerize at the same time to yield a produce which is not a mixture of
separate polymers but a complex having properties different from either polymer alone.
See polymer. Examples are polyvinyl acetate-maleic anhydride
copolymer (day extender and selective and selective flocculant), acrylamide-carboxylic and
copolymer (total flocculant). |
| core |
n: a cylindrical
sample taken from a formation for geological analysis. Usually a conventional core
barrel is substituted for the bit and procures a sample as it penetrates the formation.
v: to obtain a formation sample for analysis. |
| core
analysis |
laboratory analysis of a core
sample to determine porosity, permeability, lithology, fluid content, angle of dip,
geological age, and probably productivity of the formation. |
| core barrel |
a tubular device, usually from 10
to 60 feet (3 to 18 meters) long, run at the bottom of the drill pipe in place of a bit
and used to cut a core sample. |
| coring |
the process of cutting a vertical,
cylindrical sample of the formations encountered as an oilwell is drilled. The
purpose of coring is to obtain rock samples, or cores, in such a manner that the rock
retains the same properties that it had before it was removed from the formation. |
| corkscrew |
the buckling of tubing in a
large-diameter pipe or casing. |
| correlate |
to relate subsurface information
obtained from one well to that of others so that the formations may be charted and their
depths and thicknesses noted. Correlations are made by comparing electrical well
logs, radioactivity logs, and cores from different wells. |
| corrosion |
any of a variety of complex
chemical or electrochemical processes, e.g., rust, by which metal is destroyed through
reaction with its environment. |
| corrosion
inhibitor |
a chemical substance that
minimizes or prevents corrosion in metal equipment. |
| coupling |
1. in piping, a metal collar with
internal threads used to join two sections of threaded pipe. 2. in power transmission, a connection extending longitudinally between a driving
shaft and a driven shaft. Most such couplings are flexible and compensate for minor
misalignment of the two shafts. |
| coupon |
small metal strip which is exposed
to corrosive systems for the purpose of determining nature and severity of corrosion. |
| crack a
valve |
to barely open a valve so that it
leaks just a little. |
| crater |
(slang) to cave in; to fail.
After a violent blowout, the force of the fluids escaping from the wellbore
sometimes blows a large hole in the ground. In this case, the well is said to have
cratered. Equipment craters when it falls. |
| creaming
of emulsions |
the settling or rising of the
particles of the dispersed phase of an emulsion. Identifiable by a difference in color
shading of the layers formed. Creaming can be either upward or downward, depending
on the relative densities of the continuous and dispersed phases. |
| created
fracture |
fracture induced by means of
hydraulic or mechanical pressure exerted on the formation. |
| crew |
1. the workers on a drilling or
workover rig, including the driller, derrickman, and rotary helpers 2. any group of oilfield workers. |
| crew chief |
the driller or head well puller in
charge of operations on a well servicing rig that is used to pull sucker rods or tubing |
| 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 of approximately 2,000 to 3,000. |
| crooked
hole |
a wellbore that has been
unintentionally drilled in a direction other than vertical. It usually occurs where
there is a section of alternating hard and soft strata steeply inclined from the
horizontal. |
| crossover |
the section of a drawworks drum
grooved for angle control and in which the wire rope crosses over to start a new wrap.
Also called an angle-control section. |
| crossover
joint |
a length of casing with one thread
on the field end and a different thread in the coupling, used to make a changeover from
one thread to another in a string of casing. |
| crown block |
an assembly of sheaves, mounted on
beams at the tope of the derrick, over which the drilling line is reeved. See block. |
| crude oil |
a mixture of hydrocarbons that
existed in the liquid phase in natural phase in natural underground reservoirs and remains
liquid at atmospheric pressure after passing through surface separating facilities. |
| crude
oil production |
the volume of liquids
statistically reported as crude oil, which is produced from oil reservoirs during given
period of time. |
| crude oil - productive capacity |
estimates of productive capacities
of crude oil developed by the American Petroleum Institute Committee on Reserves and
Productive Capacity represent the maximum daily rates of production which can be attained
under specified conditions on March 31 of any given year. |
| crude oil - proved reserves |
proved reserves of crude oil as of
December 31 of any given year are the estimated quantities of all liquids statistically
reported as crude oil, which geological and engineering data demonstrate with reasonable
certainty to be recoverable in the future from known reservoirs under existing economic
and operating conditions. |
| cubic
foot (cu ft) |
the volume of a cube, all edges of
which measure 1 foot. Natural gas in the United States is usually measured in cubic
feet, with the most common standard cubic foot being measured at 60 degrees Fahrenheit and
14.65 pounds per square inch absolute, although base conditions vary from state to state. |
| cup packer |
a device made up in the drill stem and lowered
into the well to allow the casing and blowout preventers to b pressure-tested. The
sealing device is cup-shaped and is therefore called a cup. |
| cup test |
see packer
test. |
| cup-type elements |
rubber seals that energize by pressure only,
not mechanical force; plugs and wash tools |
| custodian |
also called a lease operator or pumper.
See pumper |
| cut drilling
fluid |
well-control fluid that has been reduced in
density or unit weight as a result of entrainment of less-dense formation fluids or air |
| cut oil |
oil that contains water. |
| cuttings |
the fragments of rock dislodged by
the bit and brought to the surface in the drilling mud. Washed and dried cuttings samples
are analyzed by geologists to obtain information about the formations drilled. |
| cyclone |
1.a low-pressure area, around
which wind flow is counterclockwise in the Northern Hemisphere and clockwise in the
Southern Hemisphere. The term is sometimes used to describe storms occurring in the
atmosphere; in the Indian Ocean it is used to designate a tropical cyclone. 2. a device for the separation of various particles from a drilling
fluid, most commonly used as a desander. The fluid is pumped tangentially into a
cone, and the fluid rotation provides enough centrifugal force to separate particles by
mass weight. |
