Downhole under-reamer and associated methods

摘要

A downhole under-reamer 10 for use in reaming a downhole bore includes a body 12 and a plurality of cutters 16 mounted on the body 12. The cutters 16 are mounted on the body 12 so as to be extendable from a retracted position to at least two extended positions. The at least two extended positions comprise reaming positions at respective first and second reaming diameters.