Oil and Gas Terms Beginning with “C” — Page 7

Chrome lignosulfonate (CLS) in oilfield drilling fluid engineering is a sulfonated lignin derivative treated with chromium salts to produce a high-temperature WBM dispersant and thinner that reduces plastic viscosity,… Read more →

Chrome tubing in oilfield production engineering refers to corrosion-resistant alloy (CRA) tubulars containing chromium as the primary alloying element, principally 13 percent chromium martensitic stainless steel (13Cr,… Read more →

Chrome-free cementing and completion fluid additives are oilwell chemical products used in primary cementing, remedial cementing, and wellbore completion operations that provide the rheology control, fluid loss… Read more →

Chromic salts in oilfield drilling fluid and completion engineering are trivalent chromium (Cr3+) compounds, principally chromium acetate (Cr(CH3COO)3), chromium chloride (CrCl3), chromium propionate, and chromic oxide… Read more →

A chronostratigraphic chart in petroleum geology and basin analysis is a two-dimensional diagram that plots geological time on one axis against geographic or stratigraphic position on the other axis, representing the… Read more →

Chronostratigraphy is the branch of stratigraphy that classifies sedimentary rock sequences according to their age in geological time rather than their physical character or geographic position, establishing the… Read more →

Churn flow in petroleum production engineering is a chaotic, highly turbulent multiphase flow regime that occurs in vertical and near-vertical wellbores and pipelines when the gas-liquid ratio is high enough to cause… Read more →

Circle shooting in marine seismic acquisition is a specialized survey geometry in which the seismic vessel travels in a circular or spiraling path around a fixed surface point directly above the target structure,… Read more →

Circulate in drilling engineering refers to the continuous pumping of drilling fluid (mud) down the drill string, through the bit nozzles or open-ended drill pipe, and back up the annular space between the drill string… Read more →

Circulate out in drilling engineering is the well control procedure of pumping drilling fluid continuously around the full wellbore circuit (down the drill string, through the bit, and up the annulus to surface) to… Read more →

Circulation in drilling engineering refers to the continuous or intermittent pumping of drilling fluid (mud) through the complete hydraulic circuit of a wellbore: from the rig mud pumps through the standpipe manifold,… Read more →

A circulation device in oilfield drilling and workover engineering is a downhole tool installed in the drill string, work string, or completion tubular that allows drilling fluid, completion fluid, or treatment… Read more →

Circulation loss in drilling engineering is the condition in which drilling fluid pumped down the drill string exits the wellbore into the formation rather than returning to surface through the annulus, reducing or… Read more →

A circulation sub in oilfield drilling engineering is a short tubular tool, typically 0.5 to 1.5 metres in length, installed at a specific position in the drill string to provide a controlled means of diverting drilling… Read more →

The circulation system in drilling engineering is the integrated network of surface and downhole equipment that pumps, conditions, monitors, and recycles drilling fluid (mud) through the wellbore hydraulic circuit… Read more →

A circulation valve in oilfield drilling and completion engineering is a downhole tool installed in the drill string, work string, or production tubing that contains an internal flow control mechanism allowing the… Read more →

Citric acid in oilfield production chemistry and well stimulation is a weak triprotic organic acid (C6H8O7, molecular weight 192.12 g/mol, pKa values 3.13, 4.76, and 6.40) used principally as an iron-sequestering agent… Read more →

Classical reservoir modeling in petroleum engineering refers to the suite of analytical mathematical methods developed from the 1920s through the 1980s for forecasting reservoir performance, estimating recoverable… Read more →

Clastic sediment in petroleum geology refers to rock fragments and mineral grains derived from the physical weathering, erosion, and transport of pre-existing rocks, deposited by wind, water, or ice to form sedimentary… Read more →

Clay in petroleum engineering and geoscience refers to a group of fine-grained phyllosilicate minerals (grain size less than 4 microns by geological convention, or less than 2 microns by engineering convention) that… Read more →

A clay extender in drilling fluid engineering is a chemical additive that adsorbs onto bentonite clay platelet surfaces and enhances the viscosity-building efficiency of bentonite in water-based drilling muds (WBM),… Read more →

A clay stabilizer in oilfield engineering is a chemical additive incorporated into drilling fluids, completion brines, workover spacers, and hydraulic fracturing base fluids to prevent reactive formation clay minerals… Read more →

Clay swelling in petroleum engineering is the volumetric expansion of clay mineral crystals, principally smectite (montmorillonite) and mixed-layer illite-smectite, when water molecules penetrate the expandable 2:1… Read more →

Clay-water interaction in petroleum engineering is the ensemble of physico-chemical processes that occur when aqueous fluids contact clay mineral surfaces in formation rocks and drilling environments, encompassing… Read more →

Clay-bound water (CBW) in petroleum petrophysics is the water that is electrochemically adsorbed onto the surfaces and within the interlayer spaces of clay mineral crystals in reservoir rock, held by electrostatic… Read more →

Clay-water interaction in the context of reservoir geomechanics and log-based petrophysical analysis refers to the coupled mechanical, chemical, and electrical effects of water adsorption on clay mineral surfaces in… Read more →

Clean in petroleum engineering and petrophysics is a descriptive term applied to reservoir intervals, formation sections, or produced fluids that are free of, or contain only minimal quantities of, clay minerals, shale… Read more →

A cleanout in oilfield well operations is a workover or intervention procedure in which fill, debris, scale, paraffin, sand, cement, perforation debris, collapsed liner, or other material accumulating in the wellbore is… Read more →

Cleanup in petroleum well operations refers to the post-stimulation or post-completion flowback period during which injected fluids, drilling fluid filtrate, and particulate debris are recovered from the wellbore and… Read more →

Clear water drilling is a drilling technique in which plain water, with no intentionally added clay, polymer, or weighting material, is used as the circulating fluid to remove cuttings from the bit face and transport… Read more →