Oil and Gas Terms Beginning with “C” — Page 13

What Is Corrosion Rate? Corrosion rate (also called metal loss rate or penetration rate) is the quantitative expression of the speed at which metal is being removed from a surface by corrosion, reported in mils per year… Read more →

What Is a Corrosion-Resistant Alloy (CRA)? Corrosion-resistant alloy (CRA) (also called high-alloy steel, specialty alloy, or corrosion-resistant material) is a family of metallic alloys selected specifically for their… Read more →

What Is a Cosolvent? Cosolvent (also called mutual solvent or oilfield solvent additive) is an organic solvent added to an aqueous completion, acid, or fracturing fluid to improve the miscibility of oily or waxy… Read more →

Cost oil is the portion of petroleum production allocated to the contractor or working interest owner in a production sharing contract (PSC) or production sharing agreement (PSA) to recover capital expenditures… Read more →

What Is a Cosurfactant? Cosurfactant (also called co-solvent or secondary surfactant) is a chemical additive used alongside a primary surfactant in chemical enhanced oil recovery (EOR) to lower the interfacial tension… Read more →

A counterbalance weight in oilfield artificial lift is the cast iron or steel weight mounted on the crank arm or Pitman arm of a beam pumping unit (sucker rod pump, pumpjack) that counteracts the combined load of the… Read more →

A counterbalance winch in oilfield well service and drilling operations is a mechanical or hydraulic winch system that uses a counterweight, spring accumulator, or hydraulic accumulator to offset the weight of a tool… Read more →

A coupling in oil and gas drilling and production operations is a short, internally threaded cylindrical connector used to join two sections of pipe, tubing, casing, or other tubulars end-to-end by engaging the external… Read more →

(noun) A small metal sample of known weight, dimensions, and metallurgy that is exposed to a corrosive environment within a pipeline, vessel, or wellbore for a specified period to measure the rate of corrosion by… Read more →

Cracking in petroleum refining and bitumen upgrading is the thermal or catalytic process of breaking large, high-molecular-weight hydrocarbon molecules into smaller, lower-molecular-weight molecules by rupturing… Read more →

A craton is a large, stable, and geologically ancient segment of the earth's continental crust and lithosphere that has remained relatively undisturbed by tectonic activity for hundreds of millions to billions of years,… Read more →

Creaming in oil and gas operations refers to two distinct but related phenomena that share the underlying physics of density-driven phase separation: in the context of drilling fluids and produced fluid processing,… Read more →

The crest of a geological structure in petroleum exploration is the highest point of an anticlinal fold, dome, or reef buildup as measured in subsurface depth or elevation, representing the topographically highest… Read more →

Cresting in reservoir engineering is the upward deformation of an oil-water contact (OWC) or the downward deformation of a gas-oil contact (GOC) beneath a producing well in response to the pressure drawdown created by… Read more →

The critical angle in petroleum geophysics and directional drilling refers to two distinct but equally important concepts: in seismic refraction and borehole geophysics, the critical angle is the minimum angle of… Read more →

Critical damping in oilfield drilling and production engineering is the condition in which a mechanical or hydraulic system returns to its equilibrium position in the minimum possible time without oscillating past it,… Read more →

What Is Critical Flow Rate? Critical Flow Rate (also called sonic flow, choked flow, or Mach 1 flow) is the well flow rate at which the velocity of fluid through a nozzle, choke, or restriction equals the local sonic… Read more →

Critical gas flow rate is the volumetric gas flow rate at which the gas velocity in a pipe, tubing string, choke, or wellhead fitting reaches the acoustic velocity (speed of sound) of the flowing gas mixture under the… Read more →

Critical matrix in petroleum reservoir engineering is the near-wellbore region of the reservoir formation, typically extending 0.3 to 3 m radially outward from the borehole wall, where the combination of large pressure… Read more →

The critical moment in petroleum systems analysis is the specific point in geological time at which the key elements of a petroleum system — source rock, reservoir rock, cap rock seal, overburden, and migration pathway… Read more →

Critical rate in petroleum engineering refers to the minimum flow rate at which the flow regime in a pipe, wellbore, or porous medium transitions from laminar (Darcy) flow to turbulent (non-Darcy) flow, a transition… Read more →

Critical reflection in seismology and seismic exploration is a reflected wave that occurs at or beyond the critical angle of incidence, defined as the angle of incidence at which the refracted wave transmitted across an… Read more →

What Is a Crooked Hole? Crooked hole (also called an unintentional deviated wellbore or wild well deviation ) is a wellbore that strays from its planned vertical or directional trajectory due to natural formation… Read more →

Cross-dipole is a sonic logging configuration in which two pairs of dipole transmitters and receivers are oriented at 90 degrees to each other within the logging tool, enabling measurement of the directional dependence… Read more →

A cross section in petroleum geology and reservoir engineering is a two-dimensional vertical slice through the subsurface along a specified line or well transect, constructed by projecting well log data, seismic… Read more →

Crosscorrelation is a mathematical operation that measures how similar two signals are to each other, and how that similarity changes as one signal is shifted in time or space relative to the other. The result is a… Read more →

A cross-correlation flowmeter is a production logging tool that determines fluid velocity in the wellbore by mathematically cross-correlating the arrival times of naturally occurring or artificially introduced flow… Read more →

What Is Crossflow? Crossflow (also called inter-zonal flow or behind-pipe flow ) is the movement of formation fluids from one reservoir layer to another through the wellbore — or through natural fractures and… Read more →

Crossline in three-dimensional seismic acquisition and interpretation refers to a seismic profile oriented perpendicular to the direction of primary data acquisition (the inline direction), forming one axis of the… Read more →

What Is a Crosslinker? Crosslinker (also called a crosslinking agent or gel crosslinker ) is a chemical additive introduced into hydraulic fracturing fluid that forms covalent or ionic bonds between adjacent polymer… Read more →