Bi-center drill bit with enhanced stabilizing features

A bi-center drill bit for drilling subterranean formations, comprising:

• a pilot drag bit section having a longitudinal axis, defining a first gage diameter and including a body with a face having a first plurality of superabrasive cutters secured thereto and a gage section extending longitudinally from a periphery of said face and comprising a plurality of elongated gage pads;
• and
• a reamer bit section adjacent said pilot drag bit section including at least one blade fixedly extending radially beyond said first gage diameter on one peripheral side portion of said bit and carrying a second plurality of superabrasive cutters thereon;
• said first plurality of superabrasive cutters being placed and oriented on said pilot drag bit section face to generate, upon rotation of said bi-center bit in engagement with a subterranean formation, a lateral force on said pilot drag bit section in substantial alignment with a lateral force generated by said second plurality of superabrasive cutters responsive to said rotation, said plurality of elongated gage pads being circumferentially extended to generally oppose said lateral forces.

A method of drilling a subterranean borehole commencing from the bottom of a first diameter borehole segment and including a second, larger diameter borehole segment extending forward from said first diameter borehole segment, comprising:

• orienting and placing a fixed cutting structure on a drill bit in order to orient a first lateral force vector with a second, longitudinally spaced lateral force vector;
• rotating said drill bit on an end of a drill string and applying weight to said bit against said first borehole segment bottom to cut a pilot borehole of a diameter smaller than that of said first borehole segment;
• substantially concurrently cutting and enlarging said cut pilot borehole to said second, larger diameter borehole with a fixed laterally extended cutting structure on said drill bit while substantially concurrently applying said weight to said drill bit;
• transitioning from a pass-through axis to a drilling axis when said fixed laterally extended cutting structure commences enlargement of said cut pilot borehole to said second, larger diameter borehole;
• and
• generating said first lateral force vector while cutting said pilot borehole with said oriented and placed fixed cutting structure and said second, longitudinally spaced lateral force vector substantially laterally aligned with said first lateral force vector while enlarging said pilot borehole.