An anti-whirl rotary drag bit including one or more cutters, wear knots or other support structures disposed on the flank of a bit profile in a normally cutter-devoid region of the profile adjacent the gage of the bit in the circumferential segment of the gage used as a bearing zone for the bit to ride against the side of the bore hole. Such flank cutters or other structures reduce wear of the bearing zone but, due to their placement, do not come into play except under certain drilling situations such as reaming or high rates of penetration wherein whirl tendencies resulting from cutting forces are not as pronounced.
CROSS REFERENCE TO RELATED APPLICATION
This application is a continuation of application Ser. No. 08/197,011, filed Feb. 15, 1994, pending, which is a file wrapper continuation of application Ser. No. 07/883,667, filed May 15, 1992, abandoned.
A rotary drill bit for drilling subterranean formations configured with at least one protective structure proximate to the rotationally leading and trailing edges of a gage trimmer, wherein the at least one protective structure is positioned at substantially the same exposure as its associated gage trimmer. Particularly, the apparatus of the present invention may provide protection for gage trimmers during drilling, tripping, and/or rotation within a casing; i.e., when changing a drilling fluid. Protective structures may be configured and located according to anticipated drilling conditions including helix angles. In addition, a protective structure may be proximate to more than one gage trimmer while having a substantially equal exposure to each associated gage trimmer. Methods of use and a method of rotary bit design are also disclosed.
An expandable reaming tool including at least two reamer pads connected to a tool body. The reamer pads are adapted to be displaced between a retracted position and an expanded position. At least one spiral blade is formed on at least one reamer pad. A plurality of cutting elements are disposed on the at least one spiral blade.An expandable reaming tool including at least two reamer pads connected to a tool body. The reamer pads are adapted to be displaced between a retracted position and an expanded position. At least one spiral blade is formed on at least one reamer pad. A plurality of cutting elements are disposed on the at least one blade and at least one gage protection element is disposed on a gage surface of the at least one blade. The plurality of cutting elements are arranged so as to enable the expandable reaming tool to backream a formation in a wellbore.
Hardfacing is deposited on a PDC-equipped steel body rotary drag bit and forms substantially protruding structural elements, such as wear knots or chip breakers. Hardfacing may also be applied to features such as gage pads, wherein at least two different hardfacing compositions are utilized and specifically located in order to exploit the material characteristics of each type of hardfacing composition employed. The use of multiple hardfacing compositions may further be employed as a wear-resistant coating on various elements of the drill bit. The surfaces to which hardfacing is applied may include machined slots, cavities or grooves providing increased surface area for application of the hardfacing. Additionally, such surface features may serve to effect a desired residual stress state in the resultant hardfacing layer or other structure.
An expandable reaming tool including at least two reamer pads connected to a tool body. The reamer pads are adapted to be displaced between a retracted position and an expanded position. At least one spiral blade is formed on at least one reamer pad. A plurality of cutting elements are disposed on the at least one spiral blade.An expandable reaming tool including at least two reamer pads connected to a tool body. The reamer pads are adapted to be displaced between a retracted position and an expanded position. At least one blade is formed on the at least two reamer pads. A plurality of cutting elements are disposed on the at least one blade and at least one gage protection element is disposed on a gage surface of the at least one blade. The plurality of cutting elements are arranged so as to enable the expandable reaming tool to backream a formation in a wellbore.
A rotary-type earth-boring drag bit with cutters oriented at varied rake angles and methods for designing such drag bits. Specifically, cutters that are located sequentially adjacent radial distances from a longitudinal axis of the drill bit have cutting faces that are oriented at rake angles that differ from one another. These cutters may be located on the same blade of the drag bit or on different blades of the drag bit. The rake angles at which the cutting faces of these cutters are oriented may be based, at least in part, on the relative radial distances these cutters are spaced from the longitudinal axis of the drag bit, on the vertical positions of these cutters along the longitudinal axis of the drag bit, or in response to actual or simulated evaluations of the use of the drag bit to drill a subterranean formation.
