Abstract: New cutting structures for roller cone drill bits are disclosed. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized. Additional aspects of the invention are also disclosed.

Abstract: The invention is a drill bit that has a bit body, at least one roller cone attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on the at least one roller cone. At least one bit design parameter is selected so that the cutting elements wear in a selected manner when drilling an earth formation. The invention is also a method for designing a drill bit that has at least one roller cone and a plurality of cutting elements. The method includes several steps, beginning with selecting initial bit design parameters. The drill bit is then simulated drilling at least one selected earth formation. The wear induced change in the cutting element geometry is determined and the simulated bit is adjusted to reflect the wear. The selecting, simulating, determining, and adjusting are repeated and at least one bit design parameter of the drill bit is adjusted until at least one performance parameter of the drill bit is optimized.

Abstract: New cutting structures for roller cone drill bits. In one aspect, a drill bit includes a bit body, roller cones attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on each of the roller cones, such that axial force on the bit during drilling is substantially balanced between the cones. In another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that the amount of work performed by each cone during drilling is substantially the same as the amount of work performed by each of the other cones. In yet another aspect, a drill bit includes a plurality of cutting elements disposed on each roller cone such that distribution of axial force on the bit is optimized.

Abstract: A drill bit including a roller cone and a plurality of cutting elements. The roller cone is affixed to a bit body and is arranged circumferentially about a bit axis of rotation. In one aspect, the cutting elements are arranged so that the crests of at least half of the cutting elements are within about 10 degrees of perpendicularity to the bit axis when each of these cutting elements is in a downwardmost rotary orientation. In another aspect, the roller cone and the cutting elements are arranged so that crests on the cutting elements define a substantially flat profile. Substantially flat in this aspect includes the profile having an endmost angle, either at the gage side or the centerline side, with respect to perpendicular to the bit axis, of less than about 11 degrees.

Abstract: Cutting structures for roller cone drill bits are disclosed. One aspect is a drill bit which includes a bit body, and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. The bit further includes a plurality of cutting elements arranged on each of the roller cones so that cutting elements on adjacent cones intermesh between the adjacent cones. The cutting elements are arranged so that a rotation speed of each cone differs by less than about 7% from the rotation speed of each of the other cones during drilling. Another aspect is a drill bit which includes a bit body, and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. The bit also includes a plurality of cutting elements arranged on each of the roller cones so that cutting elements on adjacent cones intermesh between the adjacent cones.

Abstract: A method for optimizing drilling performance of a roller cone drill bit is disclosed. The method includes simulating drilling with the bit in a selected earth formation to determine at least one drilling performance parameter. The orientation of at least one non-axisymmetric cutting element on the bit is adjusted and the simulating the drilling and determining the at least one performance parameter are repeated. The adjusting and simulating the drilling are repeated until the at least one performance parameter is determined to be at an optimum value. In one embodiment, the performance parameter includes rate of penetration.

Abstract: A roller cone drill bit includes a bit body adapted to be rotated about a longitudinal axis. At least one leg which terminates in a shirttail portion depends from the bit body. The shirttail portion defines a first end face having a first circumferential groove thereon. The first circumferential groove has a radius equal to the radius of a tip of the shirttail portion. A journal is cantilevered from the leg, and a roller cone is rotatably mounted on the journal. The roller cone has a second end face adjacent to the first end face. A second circumferential groove is formed on the second end face.

Abstract: A roller cone drill bit for drilling earth formations is disclosed. The bit includes a bit body and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. The drill bit includes plurality of cutting elements disposed on each of the roller cones such that at least one of the cutting elements includes a step shaped crest on its outer surface. In one embodiment, the step shaped crest includes a difference in extent between a more extensive and less extensive crest segment selected to correspond to a penetration depth in a particular earth formation at which fracture failure is expected. Other embodiments include one or more flank surfaces having more and less extensive surfaces thereon corresponding to the more and less extensive crest segments.

Abstract: A method for optimizing drilling performance of a roller cone drill bit is disclosed. The method includes simulating drilling with the bit in a selected earth formation to determine at least one drilling performance parameter. The orientation of at least one non-axisymmetric cutting element on the bit is adjusted and the simulating the drilling and determining the at least one performance parameter are repeated. The adjusting and simulating the drilling are repeated until the at least one performance parameter is determined to be at an optimum value. In one embodiment, the performance parameter includes rate of penetration.

Abstract: The invention is directed to a roller cone drill for drilling earth formations and a method of using the same. The drill bit includes a bit body and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. The drill bit further includes a plurality of cutting elements disposed on each of the roller cones, an offset of at least about 0.375 inches; and a journal angle less than about thirty degrees. In one embodiment, the drill bit includes three roller cones. In another embodiment, the cutting elements of the bit are arranged on each cone so that cutting elements on adjacent cones intermesh between the cones.

Abstract: A drill bit comprising a bit body, at least one roller cone rotatably mounted on the bit body. The cone has a plurality of milled teeth at selected locations on the cone. At least one of the milled teeth comprises a substrate having a convex crest and a layer of hardfacing applied to said convex crest. The convex crest is adapted to produce at least one of a convex axial stress distribution, a substantially even axial stress distribution, and a substantially smooth axial stress distribution.

Abstract: The invention is a drill bit that has a bit body, at least one roller cone attached to the bit body and able to rotate with respect to the bit body, and a plurality of cutting elements disposed on the at least one roller cone. At least one bit design parameter is selected so that the cutting elements wear in a selected manner when drilling an earth formation.

Abstract: A novel rolling cone rock bit includes a plurality of PDC or other cutters mounted to the leg of the drill bit and positioned to cut the troublesome corner of the bottomhole. The plurality of cutters may be the primary cutting component at gage diameter, or may be redundant to gage teeth on a rolling cutter that cut to gage diameter. Consequently, the occurrence of undergage drilling from the wear and failure of the gage row on a rolling cutter is lessened. Another inventive feature is the inclusion of a mud ramp that creates a large junk slot from the borehole bottom up the drill bit. The resulting pumping action of the drill bit ramp speeds up the removal of chips or drilling cuttings from the bottom of the borehole, reduces the level of hydrostatic pressure at the bottom of the borehole and minimizes the wearing effect of cone inserts regrinding damaging drill cuttings.

Abstract: Provided are methods, data communication apparatus and computer programs for managing communications between a remote communication manager and a set of communications managers in an associated group. The group of communication managers have shared access to resources which enable any communication manager in the group to recover from failures experienced by another communication manager in the group. In particular, recovery of failed inbound and outbound channels is achieved with the advantage of improved availability of data transmissions. Preferably, the recovery uses synchronization information to ensure that data is recovered to a consistent state to that channel recovery is achieved without loss of data integrity.

Abstract: The invention is directed to a roller cone drill for drilling earth formations. The drill bit includes a bit body and a plurality of roller cones attached to the bit body and able to rotate with respect to the bit body. The drill bit further includes a plurality of teeth disposed on each of the roller cones such that the number of teeth on each cone differs by two or fewer from the number of teeth on each of the other cones. In one preferred embodiment, the drill bit includes three roller cones. In another preferred embodiment, the teeth of the bit are arranged on each cone so that teeth on adjacent cones intermesh between the cones. In another preferred embodiment, the drill bit includes a first cone, a second cone, and a third cone, and the number of teeth on each of the cones is 17, 16, and 18, respectively.

Abstract: A roller cone drill bit includes a bit body adapted to be rotated about a longitudinal axis. At least one leg depends from the bit body, and a journal is cantilevered from the leg. A roller cone is rotatably mounted on the journal. A cone retention member is disposed between a first slot in the journal and a corresponding second slot in the roller cone. An access hole runs through the journal to the first slot, penetrating the first slot at a location away from the top dead center of the first slot.