Total feet of casing run in a well.

Casing is manufactured in lengths of about 30 ft, each length or joint being joined to another as casing is run in a well. The entire length of the joints of casing is called the casing string.

Casing string is a long section of connected oilfield pipe that is lowered into a wellbore and cemented. The pipe joints are typically about 40 ft [12 m] in length, male threaded on each end and connected with short lengths of double-female threaded pipe called couplings.