Oil and Gas Terms Beginning with “C” — Page 3

What Is Carbon/Oxygen Ratio Logging? Carbon/oxygen (C/O) ratio logging (also called C/O logging, carbon-oxygen spectroscopy, or pulsed neutron spectroscopy saturation logging) is a cased-hole formation evaluation… Read more →

Carbon dioxide (CO2) is a colorless, odorless gas with the molecular formula CO2 that plays multiple critical and often competing roles in petroleum operations. As a naturally occurring compound formed by the complete… Read more →

What Is Carbon Dioxide Corrosion? Carbon dioxide corrosion (CO2 corrosion, also called sweet corrosion) is the degradation of steel wellbore tubulars, pipelines, and surface equipment caused by the reaction of dissolved… Read more →

A carbonate, in petroleum geology, refers both to a class of minerals and to the sedimentary rocks composed predominantly of those minerals. The principal carbonate minerals are calcite (CaCO3), dolomite (CaMg(CO3)2),… Read more →

What Is the Carbonate Ion? The carbonate ion (CO₃²⁻) is a divalent anion formed in aqueous solution when carbon dioxide (CO₂) dissolves in water and undergoes sequential dissociation — first forming carbonic acid… Read more →

What Is Carbonate Scale? Carbonate scale is a hard mineral deposit — primarily calcium carbonate (CaCO₃, calcite or aragonite), with lesser amounts of iron carbonate (FeCO₃, siderite) — that precipitates from produced… Read more →

What Is a Carbonate Test? A carbonate test is a standard field test performed on drilling fluid filtrate or produced water to quantify the concentration of carbonate (CO₃²⁻) and bicarbonate (HCO₃⁻) ions in the aqueous… Read more →

What Is Carboxymethyl Hydroxyethylcellulose? Carboxymethyl hydroxyethylcellulose (CMHEC, also written CM-HEC or carboxymethyl HEC) is a mixed cellulose ether — a water-soluble polymer derived from cellulose by… Read more →

What Is Carboxymethyl Starch? Carboxymethyl starch (CMS, sodium carboxymethyl starch) is an anionic starch derivative produced by reacting native starch (from corn, potato, tapioca, or wheat) with monochloroacetic acid… Read more →

A 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… Read more →

What Is Carboxymethylcellulose? Carboxymethylcellulose (CMC, sodium carboxymethylcellulose, NaCMC) is a water-soluble anionic polymer derived from cellulose by reacting it with monochloroacetic acid under alkaline… Read more →

A carried working interest (CWI) is a contractual arrangement in petroleum exploration and production whereby one working interest owner, called the carried party, has some or all of its share of drilling and completion… Read more →

What Is a Carrier Fluid? A carrier fluid is the liquid medium used to transport and suspend solid materials — most commonly proppant in hydraulic fracturing operations — from surface into the wellbore and placement… Read more →

What Is a Carrier Gun? A carrier gun is the most common type of perforating gun used in oil and gas well completions — a steel tube or housing that contains shaped-charge perforating charges mounted on a charge carrier… Read more →

What Is Carrying Capacity? Carrying capacity (also called hole-cleaning efficiency or cuttings transport efficiency) is the ability of a drilling fluid to lift and transport rock cuttings from the bit face at the bottom… Read more →

What Is Carryover? Carryover in oil and gas production operations refers to the unintended transfer of liquid droplets or slugs from a gas stream into downstream gas processing equipment — or, conversely, gas bubbles… Read more →

What Is a Perforating Cartridge? Perforating cartridge (also called a gun cartridge, shaped charge assembly, or perf charge) is a single shaped charge unit loaded into a perforating gun carrier, consisting of a… Read more →

What Is Cased Hole in Oil and Gas? Cased hole refers to any section of a wellbore where steel casing has been run and cemented in place, as distinguished from "open hole" — the uncased, exposed formation section. Most… Read more →

What Is Casing? Casing is the steel pipe set and cemented inside a wellbore to isolate formations, support wellbore walls, and contain pressure during the life of an oil or gas well. Operators install progressively… Read more →

What Is a Casing Bowl? A casing bowl (also called a casing head or casing spool) is the lowest component of the wellhead assembly, welded or threaded to the top of the first (conductor or surface) casing string and… Read more →

What Is Casing Burst Pressure? Casing burst pressure is the internal pressure at which a casing string will fail by radial expansion and rupture of the pipe body — the maximum internal wellbore pressure the casing can… Read more →

What Is a Casing Centralizer? A casing centralizer is a mechanical device attached to the outside of the casing string at regular intervals to hold the casing away from the borehole wall, maintaining a minimum annular… Read more →

What Is a Casing Collar? A casing collar is the externally threaded coupling that connects adjacent joints of casing pipe end-to-end — a thick-walled sleeve with internal API or proprietary threads on both ends that… Read more →

What Is a Casing Collar Locator? A casing collar locator (CCL) is a wireline logging instrument that detects the casing collars — the threaded coupling joints between adjacent casing joints — by measuring the change in… Read more →

What Is a Casing Collar Log? A casing collar log (CCL) is a wireline logging measurement that detects the magnetic anomalies created by casing collars — the steel couplings connecting adjacent joints of casing pipe — to… Read more →

What Is a Casing Completion? A casing completion is a well completion design in which the production casing string is cemented through the entire producing interval and then selectively perforated with shaped charges to… Read more →

What Is a Casing Coupling? A casing coupling (also called a casing collar) is a short, externally-flanged cylindrical sleeve with internal threads at both ends that connects two adjacent casing joints by screwing onto… Read more →

What Is Casing Grade? Casing grade refers to the steel specification of a casing pipe — a standardised designation (H-40, J-55, K-55, N-80, L-80, C-90, T-95, P-110, Q-125, and others) defined by API Specification 5CT… Read more →

What Is a Casing Gun? A casing gun is a type of shaped-charge perforating gun designed with an outside diameter large enough to be run inside the casing string (rather than through the production tubing), enabling the… Read more →

What Is a Casing Hanger? A casing hanger is a wellhead component that supports the weight of a string of casing suspended in the wellbore — transferring the load from the casing string to the wellhead housing (or casing… Read more →