The space around a pipe (casing or tubing) suspended in a wellbore is often termed the ANNULUS, and its outer wall may be either the wall of the borehole or the casing.
The space between the tubing/casing in the wellbore; sometimes termed the annulus.
Annular Space - The space between the well bore and the outside of the well casing.
The space between a well casing pipe and the drilled borehole into which the casing is inserted. See: well
A ring-shaped space located between two circular objects, such as two pipes.