초록 ▼

A rotary drag bit suitable for directional drilling. The bit includes a bit body from which extend radially-oriented blades carrying PDC cutters. The blades extend to primary gage pads, above which secondary gage pads are either longitudinally spaced or rotationally spaced, or both, defining a gap o

A rotary drag bit suitable for directional drilling. The bit includes a bit body from which extend radially-oriented blades carrying PDC cutters. The blades extend to primary gage pads, above which secondary gage pads are either longitudinally spaced or rotationally spaced, or both, defining a gap or discontinuity between the primary and secondary gage pads through which drilling fluid from adjacent junk slots may communicate laterally or circumferentially. Longitudinally leading edges of the secondary gage pads carry cutters, such as chisel-shaped cutters for smoothing the sidewall of the borehole. The cutters are preferably configured and oriented so as to provide a relatively aggressive cutting edge to the formation in both longitudinal and rotational directions of bit movement. Cutters may likewise be disposed on the trailing ends of the secondary gage pads to provide an up-drill capability to facilitate removal of the bit from the borehole.

대표청구항 ▼

[ What is claimed is:] [1.]1. A rotary drag bit for drilling a subterranean formation, comprising:a bit body having a longitudinal axis and extending radially outward therefrom toward a gage, the bit body including a face to be oriented toward the subterranean formation during drilling and carrying

[ What is claimed is:] [1.]1. A rotary drag bit for drilling a subterranean formation, comprising:a bit body having a longitudinal axis and extending radially outward therefrom toward a gage, the bit body including a face to be oriented toward the subterranean formation during drilling and carrying cutting structure for cutting the subterranean formation;a plurality of circumferentially-spaced gage pads disposed about a periphery of the bit body and extending radially therefrom and longitudinally away from the bit face, at least some of the gage pads having a longitudinally leading surface comprising a generally radially outward fading portion inclined with respect to the longitudinal axis and carrying at least one chisel-shaped cutter thereon, the at least one chisel-shaped cutter including a portion exposed above the generally radially outward facing portion of the longitudinally leading surface; andat least one of the chisel-shaped cutters comprising at least one cutting surface oriented at a preselected angle with respect to a line perpendicular to the subterranean formation, taken in a direction of intended bit rotation.