Oil and Gas Terms Beginning with “C” — Page 2

What Is Cable Tool Drilling? Cable tool drilling (also called percussion drilling or churn drilling) is one of the oldest methods of drilling oil and gas wells — a technique in which a heavy, chisel-like drill bit… Read more →

[CaCO3]The crystalline form of calcium carbonate and chief constituent of limestone and chalk. Calcite reacts readily with dilute hydrochloric acid [HCl], so the presence of calcite can be tested by simply placing a… Read more →

What Is Calcium Bromide? Calcium bromide (CaBr₂) is a dense, highly soluble ionic salt used as a completion brine and workover fluid in oil and gas operations — providing clear, solids-free brines at densities beyond… Read more →

Calcium carbonate (chemical formula CaCO3) is a naturally occurring inorganic compound that is one of the most abundant minerals on Earth, found in limestone, chalk, marble, and biological skeletal materials. In the oil… Read more →

What Is a Calcium Carbonate Plug? A calcium carbonate plug is a temporary wellbore plug or bridging material made from granular or powdered calcium carbonate (CaCO₃, limestone) that is pumped into the wellbore or… Read more →

What Is Calcium Chloride? Calcium chloride (CaCl₂) is an ionic salt compound widely used in oil and gas operations as a drilling fluid additive, completion fluid base, and workover brine — valued for its high solubility… Read more →

What Is Calcium Contamination? Calcium contamination is the introduction of excessive calcium ions (Ca²⁺) into a water-based drilling fluid system — causing severe degradation of mud properties through the flocculation… Read more →

What Is Calcium Hydroxide? Calcium hydroxide (Ca(OH)₂, also called slaked lime or hydrated lime) is a strong base produced by the reaction of calcium oxide (quicklime, CaO) with water — and a ubiquitous chemical in oil… Read more →

What Is Calcium Mud? A calcium mud is a water-based drilling fluid system in which calcium ions (Ca²⁺) are the primary cation controlling the electrochemical environment of the mud — typically achieved through the… Read more →

What Is Calcium Naphthenate? Calcium naphthenate is an organic calcium salt that forms as a tenacious, soap-like solid deposit in oil production systems when naphthenic acids naturally present in crude oil react with… Read more →

What Is Calcium Oxide? Calcium oxide (CaO, quicklime) is the principal reactive compound produced by the calcination of limestone (calcium carbonate, CaCO₃) at 900-1,200°C — and is the fundamental chemical precursor to… Read more →

What Is Calcium Sulfate? Calcium sulfate (CaSO₄) is an inorganic mineral compound that precipitates as scale in oil and gas production systems, injection lines, and drilling fluids when the solubility limit of calcium… Read more →

What Is a Calcium Test? A calcium test is a quantitative chemical analysis performed on a drilling fluid sample to measure the concentration of dissolved calcium ions (Ca²⁺) in the mud filtrate — a key parameter in… Read more →

Calibration is the process of establishing a documented, traceable relationship between the output of a measurement instrument and a known reference standard, so that readings from different tools, different operators,… Read more →

A deposit of sodium nitrate that is mined and used for fertilizer in parts of South America. Read more →

What Is a Caliper Log? A caliper log records the physical diameter of a wellbore at multiple azimuths as a function of depth, using spring-loaded mechanical arms that press against the borehole wall and transmit their… Read more →

The device used in early logging to record logging measurements on photographic film. The camera consisted of a light shining on galvanometers, which reflected the light to produce a trace on one or more films. The… Read more →

A small, electrically activated explosive charge that detonates a larger charge. Caps, also called seismic caps or blasting caps, are used for seismic acquisition with an explosive source to achieve consistent timing of… Read more →

A cap rock is any relatively impermeable rock unit that overlies a porous and permeable reservoir rock, physically preventing the upward migration of hydrocarbons and forming the top and lateral boundaries of a… Read more →

What Is Capping a Well? Capping a well is an emergency well control operation in which a mechanical device (a capping stack or emergency wellhead assembly) is installed on top of a blowing-out or uncontrolled wellhead… Read more →

What Is a Capacitance Log? A capacitance log is a production logging tool that measures the dielectric properties of the fluid flowing in the wellbore — distinguishing oil and water phases based on their markedly… Read more →

(noun) An instrument that measures the dielectric constant or capacitance of a fluid mixture flowing through a pipe or conduit, used in production logging and surface facilities to determine the water cut or oil-water… Read more →

What Is the Capillary Number? The capillary number (N_c or N_ca) is a dimensionless ratio that compares viscous forces driving fluid flow through a porous medium to capillary forces retaining residual fluid in the pore… Read more →

A capillary pressure curve is a laboratory-derived or theoretically calculated relationship that describes the capillary pressure (Pc) required to achieve a given wetting-phase saturation in a porous rock sample. In… Read more →

What Is the Capillary Suction Time (CST) Test? Capillary suction time (CST) test (also called the CST filtration test ) is a rapid filtration measurement for drilling fluids, drilling waste slurries, and dewatering… Read more →

What Is a Capillary Tube Viscometer? Capillary tube viscometer (also called a capillary viscometer or Hagen-Poiseuille viscometer) is a laboratory instrument that measures the absolute viscosity of a fluid by timing the… Read more →

A type of static filtration test for water-base drilling fluid that measures the filtration rate (time for free water to pass between two electrodes) using filter paper as the medium. It is used primarily to indicate… Read more →

What Is a Caprock? A caprock (also cap rock or caprock seal) is the impermeable or very low permeability rock layer that overlies a hydrocarbon reservoir and prevents buoyant oil and gas from escaping upward — it is the… Read more →

What Is a Capsule Gun? A capsule gun is a type of wireline perforating gun in which individual shaped charges are each enclosed in a separate, self-contained steel or fiberglass capsule (rather than being mounted inside… Read more →

What Is a Carbide Lag Test? A carbide lag test is a procedure used in drilling operations to determine the annular lag time — the time required for drilling fluid (mud) to travel from the drill bit at bottom of the… Read more →