Patent ID: 8141627

Claim:
Apparatus useful for cleaning the interior surface of a generally cylindrically-shaped member in a subterranean well, the interior surface at least partially surrounding a bore in the generally cylindrically-shaped member, the apparatus comprising: a housing having an at least partially tubular shape and at least one bore therethrough, said housing being deployable and moveable within the cylindrically-shaped member; a plurality of mill blades supported on said housing, each said mill blade being initially spring-biased radially outwardly from said housing into at least one extended position and thereafter moveable therefrom into at least one retracted position, wherein said mill blades are configured in said extended position when said housing enters the generally cylindrically-shaped member, each said mill blade being spirally-oriented and having at least one cleaning face capable of contacting the interior surface of the cylindrically-shaped member when said mill blades are in an extended position, said mill blades being arranged in at least first and second rows on said housing so that said plurality of cleaning faces will, in combination, span the entire circumference of the bore of at least a portion of the cylindrically-shaped member when said housing is deployed within the cylindrically-shaped member; and a plurality of retraction springs, at least one said retraction spring being engaged with and capable of assisting in biasing one of said mill blades into at least one said retracted position, wherein said mill blades in said extended position are capable of cleaning the interior surface along substantially the entire circumference of at least a portion of the cylindrically-shaped member upon reciprocation of said housing.