C
Capping
To close a well so oil and/or gas do not flow out.
Cap rock
The impermeable layer above an oil or gas reservoir, preventing hydrocarbons from migrating towards the surface.
Casing
A steel pipe that is being cemented in a well in order to prevent the sides of the well to fall in and to avoid unwanted fluids or particles to flow into the well.
Casing collar locator (CCL)
Equipment used to confirm or coordinate treatment depth by using known points of reference on the casing string. CCL is an electrical logging tool that detects the magnetic irregularities caused by the relatively high mass of the casing collar.
Casing head
The upper part of the casing. This part point up above the bottom of the sea, after which other tools can be fitted.
Casing perforation
Perforation of the casing with the purpose of allowing oil or gas to flow into the well.
Casing point
The well depth where production casing should be put according to the contract and tests that have been carried out previously.
Casing seat
The lowest point in the well where the casing collar is set.
Casing shoe
A reinforced section that is mounted to the lower part of the casing collar, which is done to protect it against bucking or deformation when it is pushed down the wellbore.
Casing shoe
Cavitation
When the pressure in a fluid drops so under-pressure bubbles are generated. These bubbles “eat” the metal edges they are brought into contact with.
Cementing
A process where cement is pumped down the casing collar and set in order to keep the casing in place.
Centraliser
Equipment that is mounted on the casing collar to keep it away from the sides of the wellbore during cementing.
Chemical cutter
Down hole equipment run on wireline that cuts off the tubing at a predetermined point when the string is stuck. When the chemical cutter is activated, it directs a series of high-pressure jets of very corrosive material in a circumferential pattern. Due to the almost instantaneous corrosion of the surrounding tubing walls, an almost even cut with minimal distortion is created, allowing for an easier fishing operations.
Chemical cutter
Choke
A device that restricts the flow and therefore is able to control the flow of fluids.
Christmas tree
An assembly of valves etc. fitted to the wellhead of a completed well to control production. It helps prevent a possible blowout.
Christmas tree
CMP (Common midpoint)
A term to describe that a registered seismic indication was reflected at a point halfway down (horizontally) between the source and the detector.
Coiled tubing
A long section of small diameter pipe rolled up on coil.
Coiled tubing
Compensators
Hydraulic equipment that levels the up and downwards movements on a floating drilling rig.
Completion
A term describing all the pipes and valves in the well.
Compressor
Equipment that pumps natural gas through a pipeline. It is also used to compress the natural gas so it can be pushed back into the underground and thereby increase the pressure on the oil reservoirs.
Conductor pipe
Steel pipe with large diameter and also the first casing to be set down hole.
Containment boom
A floating sausage-shaped boom that is placed at the surface of the sea to seal in an oil leakage.
Continental Shelf
Waters along the continentals with a maximum depth of approx. 650 ft (200 meters).
Core (samples)
A cylinder-shaped rock specimen or sediments that are being drilled out and pulled out of the wellbore using special equipment.
Crossover sub
Fitting that connects to drill strings of different diameter.
Cunifer
An alloying whos name is a contraction of cobber, nickel and ferrum. Pipes of this alloying are lighter but non-corroding compared to steel pipes.
Cuttings
Particles or small chips of rocks that are being cut out when the drill bit rotates against the bottom. They are retrieved from a well when the mud is circulating.
Cyclone
A mechanism that applies centrifugal power to remove materials like dust from the drilling mud
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