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[0010]Embodiments of a rotary drag bit include a bit body having a face and an axis, a plurality of blades extending longitudinally and radially over the face, and at least one split cutter set. Each cutter of the split cutter set includes a cutting surface protruding at least partially from, or exposed beyond, a surface of a blade of the drag bit. All of the cutters of a split cutter set are located substantially the same radial distance from the central axis of the bit and may be located at substantially the same elevation along the central axis of the bit or at locations that enable them to substantially traverse a common cutting path upon rotation of the bit body about its central axis. A split cutter set includes a first primary cutter on a first blade and a corresponding second primary cutter on a different, second blade. One of the first a
Problems solved by technology
While the PDC cutting element improves drill bit efficiency in drilling many subterranean formations, the PDC cutting element is nonetheless prone to wear when exposed to certain drilling conditions, resulting in a shortened life of a rotary drag bit using such cutting elements.
The decrease in the penetration rate is a manifestation that the cutting elements of the rotary drag bit are wearing out, particularly when other drilling parameters remain constant.
While researchers co
Method used
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[0062]In accordance with the first embodiment of the invention as shown in FIG. 1, the rotary drag bit 110 comprises three blades 131, 132, 133, three primary cutter rows 141, 142, 143 and three backup cutter groups 151, 152, 153, respectively. While three backup cutter groups 151, 152, 153 are included, it is contemplated that the drag bit 110 may include one backup cutter group on one of the blades or a plurality of backup cutter groups on each blade greater or less than that illustrated. Further, it is contemplated that the drag bit 110 may have more or fewer blades than the three illustrated. Each of the backup cutter groups 151, 152, 153 may have one or more backup cutter sets. For example, without limitation, the backup cutter group 152 includes three backup cutter sets 152′, 152″, 152′″. A detailed description of backup cutter sets 152′, 152″, 152′″ of the backup cutter group 152 is now provided.
[0063]Each primary cutter row 141, 142, 143 is arranged upon each blade 131, 132,...
Example
[0119]FIG. 25 shows a cutter and blade profile 630 for the second embodiment of the invention. The drag bit 610 has a cutter density of 51 cutters and a profile as represented by cutter and blade profile 630. The cutters 614 for purposes of the drag bit 610 are numbered 1 through 51. The cutters 1-51, while they may include aspects of other embodiments of the invention, should not be confused with the numerically numbered cutters of the other embodiments of the invention. Specific cutter profiles for each of the blades 631, 631′, 632, 632′, 633, 633′ are shown in FIGS. 26 through 31, respectively.
[0120]The blade 631 illustrated in FIG. 26 includes a second cutter row 651 and a first cutter row 641 having a second cutter 18 underexposed by fifty thousandths (0.050) of an inch (1.27 millimeters) rotationally trailing a fully exposed primary cutter 17, and a second cutter 30 underexposed by fifteen thousandths (0.015) of an inch (0.381 millimeters) rotationally trailing a fully exposed...
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Abstract
A rotary drag bit includes a bit body having a face and an axis, a plurality of blades extending radially and longitudinally outward from the face, and at least one split cutter set. The split cutter set includes a plurality of cutters, where at least two of the cutters are primary and/or kerfing cutters located on different blades of the plurality of blades. The pair of primary and/or kerfing cutters of the split cutter set may be located substantially the same radial distance from a center line, or axis of rotation, of the bit and located at substantially the same longitude, or elevation, on the bit as one another, or follow substantially the same rotational or helical cutting path as each other. In addition, at least one backup cutter may be located substantially the same radial distance from a center line, or axis of rotation, of the bit and located at substantially the same longitude, or elevation, on the bit as one or both primary and/or kerfing cutters, or follow substantially the same rotational or helical path as one or both of the primary and/or kerfing cutters. The cutters of a split cutter set may be configured and oriented to provide improved bit life and reduced stress on the cutters. Other embodiments of rotary drag bits are also provided, including methods therefor.
Description
CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of U.S. Provisional Patent Application Ser. No. 60 / 897,457, filed Jan. 25, 2007, for “ROTARY DRAG BIT,” the entire disclosure of which is hereby incorporated herein by this reference.TECHNICAL FIELD[0002]The present invention, in several embodiments, relates generally to a rotary drag bit for drilling subterranean formations and, more particularly, to rotary drag bits having select plural kerfing cutter configurations configured to enhance cutter life and performance, including methods therefor.BACKGROUND[0003]Rotary drag bits have been use for subterranean drilling for many decades, and various sizes, shapes and patterns of natural and synthetic diamonds have been used on drag bit crowns as cutting elements. A drag bit can provide an improved rate of penetration (ROP) over a tri-cone bit in many formations.[0004]Over the past few decades, rotary drag bit performance has been improved with the use of a p...
Claims
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