C

Cable tool drilling.: A method of drilling a well by allowing a weighted bit (or chisel) at the bottom of a cable to fall against the formation being penetrated. The cuttings are then bailed from the bottom of the well bore with a bailer. See: rotary drilling.
Cake consistency.: According to API RP 13B, can be described as hard, soft, tough, rubbery, firm, etc.
Cake thickness.: (1) A measurement of the thickness of the filter cake deposited by a drilling fluid against a porous medium, usually filter paper, according to the standard API filtration test. Cake thickness is usually reported in 32nds of an inch or millimeters. (2) A parameter of the filter cake deposited on the wall of the borehole. See: filter cake, wall cake.
Calcium.: One of the alkaline earth elements with a valence of 2 and an atomic weight of about 40. Calcium compounds are a common cause of the hardness of water. Calcium is also a component of lime, gypsum, limestone, etc.
Calcium carbonate.: (1) CaCO ₃. An acid soluble calcium salt sometimes used as a weighting material (limestone, oyster shell, etc.) in specialized drilling fluids. (2) A term used to denote a unit and/or standard to report hardness. See: limestone.
Calcium chloride.: CaCl ₂. A very soluble calcium salt sometimes added to drilling fluids to impart special inhibitive properties, but used primarily to increase the density of the liquid phase (water) in completion fluids and as...

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Drilling Fluids Processing Handbook