Oil & Gas Terms in Category C

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.

Conductivity (fracture flow)

The permeability of the pack times its width.

Expressed in md-ft.



The change from a liquid to a thickened, curd-like state by chemical reaction.


The combining of globules in an emulsion caused by molecular attraction of the surfaces.


High point.


A stretching or tightening device that crawls along a length of chain.


Small pieces of rock that break away due to the action of the bit teeth.

Cuttings are screened out of the liquid mud system at the shale shakers and are monitored for composition, size, shape, color, texture, hydrocarbon content and other properties by the mud engineer, the mud logger and other on-site personnel.

The mud logger usually captures samples of cuttings for subsequent analysis and archiving.

Company man

The representative of the oil company or operator on a drilling location.

For land operations, the company man is responsible for operational issues on the location, including the safety and efficiency of the project.

Even administrative managers are expected to respond to the direction of the company man when they are on the rigsite.

Offshore, depending on the regulatory requirements, there may be an offshore installation manager, who supervises the company man on safety and vessel integrity issues, but not on operational issues.





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.


Large-diameter pipe lowered into an openhole and cemented in place.

The well designer must design casing to withstand a variety of forces, such as collapse, burst, and tensile failure, as well as chemically aggressive brines.

Most casing joints are fabricated with male threads on each end, and short-length casing couplings with female threads are used to join the individual joints of casing together, or joints of casing may be fabricated with male threads on one end and female threads on the other.

Casing is run to protect fresh-water formations, isolate a zone of lost returns or isolate formations with significantly different pressure gradients.

The operation during which the casing is put into the wellbore is commonly called “running pipe.” casing is usually manufactured from plain carbon steel that is heat-treated to varying strengths, but may be specially fabricated of stainless steel, aluminum, titanium, fiberglass and other materials.

Calcium hydroxide

The active ingredient of slaked (hydrated) lime, and the main constituent in cement (when wet).

Referred to as “lime” in field terminology.

Connate water

Water inherent to the producing formation; or fossil sea water trapped in the pore spaces of sediments during their deposition.


Genericized trademarks such as chiksan (often misspelled chicksan) are often used to refer to marine loading arms regardless of their manufacturer.

see marine loading arm.

Circulation sub

A downhole tool typically used with motors or assemblies that restrict the allowable fluid-circulation rates.

When operated, the circulation sub allows a higher circulation rate to be established by opening a path to the annulus in the top section of the tool string.

This is especially useful in applications such as drilling in slim-diameter wells, where a higher circulation rate may be necessary to effect good cuttings transport and hole cleaning before the string is retrieved.

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.


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.

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.