Patent ID: 8448724

Claim:
A hole opener having a hybrid reaming section for downhole earth boring operations, the hole opener comprising: a reamer body having a central longitudinal axis of rotation, an outer periphery, and upper and lower ends; a stem extending through the body of the bit and below the lower end, the stem circumscribing the central longitudinal axis of rotation; a plurality of rolling cutter mounts coupled to the outer periphery about the longitudinal axis and depending downwardly; a rolling cutter rotatably coupled to each mount, the rolling cutters defining a rolling cutter cutting profile having a rolling cutter cutting diameter; a plurality of fixed blade cutters coupled to the outer periphery and defining a fixed blade cutter cutting profile having a fixed blade cutter cutting diameter, each fixed blade cutter being coupled between adjacent rolling cutter mounts; wherein at least one of the fixed blade cutters is asymmetrically coupled about the longitudinal axis; wherein the fixed blade cutter cutting diameter and the rolling cutter cutting diameter collectively define a gage cutting diameter of the hole opener; wherein the stem has a diameter less than the gage cutting diameter; and wherein at least a portion of the fixed blade cutting profile projects in an axial direction parallel to the central longitudinal axis further than some of the cutting elements on the roller cutters defining the rolling cutter cutting profile.