Abstract
Drilled wellbores have evolved from nearly vertical, shallow holes to tortuous, deep, directionally drilled wells. As wellbore geometries have increased in complexity, so has the potential of damage resulting from casing wear. It is not unusual to routinely install ditch magnets in the returned drilling fluid circuit to catch the iron filings created by tool joint wear against the casing or riser interior wall.
While most "straight" holes attempt to control inclination, azimuth control is often times neglected, potentially creating a tortuous path. In directionally drilled holes, including horizontal and multi-lateral wells, the drill string tension holds the rotating tool joints against the inner wall of the casing for extended periods. This results in the generation of crescent shaped wear grooves (key seating) in the inner wall of the casing, often dangerously weakening casing or riser strings making them more susceptible to burst or collapse.
Some investigators have sought to quantify this damage process. Computer models describe, measure, and predict damage from casing or riser wear. From these on-going studies, advances in technology continue to minimize casing and riser wear.
