Core testing

A cylindrical sample of geologic formation usually reservoir rock, taken during or after drilling a well. Cores can be full-diameter cores (that is, they are nearly as large in diameter as the drill bit) taken at the time of drilling the zone, or sidewall cores (generally less than 1 in. [2.5 cm] in diameter) taken after a hole has been drilled. Cores samples are used for many studies, some of which relate to drilling fluids and damage done by them.