Oil and Gas Terms Beginning with “C” — Page 14

A short subassembly used to enable two components with different thread types or sizes to be connected. Read more →

A specialized tool, frequently used in gravel-pack operations, that enables the circulation of the treatment fluid (slurry) from the internal flow path of the tool string into the annulus area to be packed. The returned… Read more →

A two-dimensional plot with one variable scaled in the vertical (Y) direction and the other in the horizontal (X) axis. The scales are usually linear but may be other functions, such as logarithmic. Additional… Read more →

The porosity obtained by plotting two porosity logs against each other, normally density and neutron porosity. The computation assumes a particular fluid, usually fresh water, and particular response equations. The… Read more →

A technique for measuring formationresistivity between two or more wells. This technique measures the signal between an electromagnetic induction transmitter in one well, and a receiverarray located in another well. The… Read more →

A crosswell seismic technique that incorporates reflection traveltimes and direct traveltimes into a tomographic inversion algorithm to produce images of seismic velocity between wells. Read more →

A survey technique that measures the seismicsignal transmitted from a source, located in one well, to a receiverarray in a neighboring well. The resulting data are processed to create a reflectionimage or to map the… Read more →

A technique for measuring a signal that is broadcast from a transmitter or source located in one well, to a receiverarray placed in a neighboring well. This technique is used to create a display of formation properties… Read more →

The fixed set of pulleys (called sheaves) located at the top of the derrick or mast, over which the drilling line is threaded. The companion blocks to these pulleys are the traveling blocks. By using two sets of blocks… Read more →

(noun) A valve installed at the top of a Christmas tree or wellhead assembly that provides the uppermost point of closure on the vertical bore of the tree, used to isolate the well during wireline operations,… Read more →

What Is Crude Oil? Crude oil is a naturally occurring liquid petroleum extracted from subsurface geological formations, composed primarily of hydrocarbon chains and varying concentrations of sulfur, nitrogen, oxygen,… Read more →

The rubblized or damaged zone surrounding a perforation tunnel where the action of the perforating charge or bullet has altered the formation structure and permeability. Although it is generally damaging to production,… Read more →

The thin, outermost shell of the Earth that is typically 5 km to 75 km thick [3 to 46 miles]. The continental crust comprises rocks similar in composition to granite and basalt (i.e., quartz, feldspar, biotite,… Read more →

The temperature at which crystals will appear in a brine solution of a given density as it cools. In preparing oilfield brines, the crystallization temperature can be used to indicate the maximum saturation (density)… Read more →

The arrangement in space of uniform spheres (atoms and molecules in mineral crystals, or grains in clastic sedimentary rocks) that results in a cubic material structure. Cubic packing is mechanically unstable, but it is… Read more →

A local geophysical anomaly generated by a man-made feature, such as electrical and communications wires, steel beams and tanks and railroad tracks. Read more →

Undesirable energy, or noise, generated by human activity, such as automobile traffic that interferes with seismic surveying, or electrical power lines or the steel in pipelines that can adversely affect electromagnetic… Read more →

The total amount of oil and gas recovered from a reservoir as of a particular time in the life of the field. Cumulative production can be referenced to a well, a field, or a basin. Read more →

The aging of cement under specific temperature and pressure conditions. Read more →

The presentation on hard copy of log data from a single measurement versus depth. The term is also used to refer to the log data themselves, as a synonym for a single log. Read more →

The generation of a theoretical equation to define a given data set. In contrast, curve matching involves the comparison of well-understood data to a data set of interest. Read more →

The graphical comparison of well-understood data sets, called type curves, to another data set. If a certain type curve closely corresponds to a data set, then an interpretation of similarity can be made, although, as… Read more →

A fluid column (usually water or nitrogen) put in the drillstem to provide the desired backpressure at the start of a drillstem test. The cushion usually serves to limit the differential pressure across the test string… Read more →

The fraction of the total flow rate produced from a well that is due to a particular fluid, for example the water cut in the case of water. The cut is normally quoted at standard surface conditions. Read more →

A crude oil that contains water, normally in the form of an emulsion. The emulsion must be treated inside heaters using chemicals, which will break the mixture into its individual components (water and crude oil). Read more →

The particle size that has a specified chance of being removed by an item of solids control equipment. Most commonly, D10, D50 and D90 cut points are specified corresponding to 10, 50 and 90% chances of removal,… Read more →

A method for recovering wirelinestuck in a wellbore. In cut-and-thread operations, the wireline is gripped securely with a special tool and cut at the surface. The cut end is threaded through a stand of drillpipe. While… Read more →

Rock pieces dislodged by the drill bit as it cuts rock in the hole. Cuttings are distinct from cavings, rock debris that spalls as a result of wellbore instability. Visual inspection of rock at the shale shaker usually… Read more →

A condensate (liquid hydrocarbon) produced at surface from cycle gas. Read more →

A gas that is compressed and injected back to the reservoir. In gas-condensate reservoirs, after the liquids or condensate are recovered at the surface, the residue gas (dry gas) is returned to the reservoir to maintain… Read more →