Patent ID: 8381843

Claim:
A well bore reamer comprising: an elongated body having a longitudinal axis and adapted at opposing upper and lower ends therealong for coupling between members of a well string for rotation and displacement therewith in a well bore; a first set of cutting elements provided on the elongated body at a fixed position along the longitudinal axis thereof and presenting a first set of cutting edges; a second set of cutting elements provided on a sleeve closing around a sleeve carrying portion of the elongated body that is disposed between the lower end of the elongated body and the fixed position of the first set of cutting elements thereon, the sleeve being slidable along the longitudinal axis and rotatable thereabout on the sleeve carrying portion of the elongated body and each set of cutting elements presenting cutting edges radially outward from the elongated body; and a lower clutch mechanism operable between the sleeve and the elongated body at a bottom end of the sleeve carrying portion of the elongated body to block rotation of the sleeve relative to the elongated body in a predetermined direction about the longitudinal axis under sliding of the sleeve into a lowered position adjacent said bottom end of the sleeve carrying portion; wherein a length of the sleeve carrying portion along the longitudinal axis is at least as great as a combined length of a span of the first cutting elements along the longitudinal axis and a span of the second cutting elements along the longitudinal axis, whereby pulling of the reamer from a dogleg in which the reamer has been sufficiently forced to lodge the first and second sets of cutting elements in respective stuck positions will initially pull only the first set of cutting elements from the respective stuck position due to relative sliding between the sleeve and the elongated body, until the elongated body is pulled far enough to engage the lower clutch mechanism against the sleeve and thus begin also pulling the second set of cutting elements from the respective stuck position.