Disclosed herein is a method of designing a roller cone bit, comprising the steps of:

• a) adjusting the orientation of at least one row of teeth on a cone, in dependence on an expected trajectory of said tooth through formation material at the cutting face;
• b) calculating the width of uncut rings of formation material, in dependence on the orientation of said row of teeth, and adjusting the position of said row of teeth in dependence on said calculated width; and
• c) recalculating the rotational speed of said cone, if the position of said row is changed, and accordingly recalculating said trajectory of teeth in said row.

Disclosed herein is a method of designing a roller cone bit, comprising the steps of:

• calculating the curved trajectory of a non-axisymmetric tooth through formation material at the cutting face, as the bit and cones rotate;
• calculating a straight line approximation to said curved trajectory; and
• orienting said tooth with respect to said approximation, and not with respect to said curved trajectory.

Disclosed herein is a method for determining a drilling parameter of each one of a plurality of roller cones on a roller cone drill bit during drilling, comprising: calculating, from a geometry of cutting elements on each of the roller cones and an earth formation being drilled by the drill bit, the drilling parameter acting on each of the cutting elements; incrementally rotating the bit and recalculating the drilling parameter acting on each of the cutting elements; repeating the incrementally rotating and recalculating for a selected number of incremental rotations; and combining the drilling parameter acting on the cutting elements on each one of the roller cones.

Disclosed herein is a method for designing a roller cone drill bit, comprising simulating the bit drilling through an earth formation wherein the simulating comprises determining an axial force on a cutting element, based on a means for determining an axial force, determining an axial force on the roller cones, based on the axial forces on the cutting elements, and angularly rotating the bit; adjusting at least one design parameter of the bit; repeating the simulating the bit drilling; and comparing a distribution of axial forces among the roller cones prior to the adjusting the at least one design parameter with a distribution of axial forces among the roller cones after adjusting the at least one design parameter.

A method of designing a roller cone drill bit is disclosed. The method comprises:

• (a) calculating the force balance conditions of a bit;
• (b) defining design variables;
• (c) determine lower and upper bounds for the design variables;
• (d) defining objective functions;
• (e) defining constraint functions;
• (f) performing an optimisation means; and
• (g) evaluating an optimised cutting structure by modelling.

A method of designing a roller cone bit is disclosed. The method comprises the steps of:

• calculating the trajectory of at least one tooth on each cone through formation material at the cutting face; and
• jointly optimising both the orientations of said teeth and the width of uncut rings on said cutting face, in dependence on said trajectory.

A novel split threaded ring bearing member (42) for rolling cutter drill bits with at least a portion of its threads (48) having a different pitch than its mating threads (40) is disclosed. The pitch difference is designed so that the threaded ring can be seated or otherwise located precisely with respect to the other bearing elements within the drill bit to effectively control the axial displacement of the rolling cutter (18) on the bearing spindle (16) within a given tolerance range. Upon assembly, the difference in thread pitch causes the opposite, opposing mating thread flanks to engage, effectively applying a tensile or compressive force to a portion of the threaded ring bearing member (42), which gradually increases as the assembly is tightened. The result is an improved rolling cutter drill bit with a threaded ring cutter bearing system with excellent resistance to back-off which will not allow significant radial movement between the engaged threads, even if some back-off of the threads occurs.

The present invention is directed to an improved method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations. The invention may be alternatively characterized as either (1) an improved downhole drill bit, or (2) a method of monitoring at least one operating condition of a downhole drill bit during drilling operations in a wellbore, or (3) a method of manufacturing an improved downhole drill bit. When characterized as an improved downhole drill bit, the present invention includes (1) an assembly including at least one bit body, (2) a coupling member formed at an upper portion of the assembly, (3) at least one operating conditioning sensor carried by the improved downhole drill bit for monitoring at least one operating condition during drilling operations, and (4) at least one memory means, located in and carried by the drill bit body, for recording in memory data pertaining to the at least one operating condition. Optionally, the improved downhole drill bit of the present invention may cooperate with a communication system for communicating information away from the improved downhole drill bit during drilling operations, preferably ultimately to a surface location. The improved downhole drill bit of the present invention may further include a processor member, which is located in and carried by the drill bit body, for performing at least one predefined analysis of the data pertaining to the at least one operating condition, which has been recorded by the at least one memory means.

The present invention is directed to an improved method and apparatus for monitoring and recording of operating conditions of a downhole drill bit during drilling operations. The invention may be alternatively characterized as either (1) an improved downhole drill bit, or (2) a method of monitoring at least one operating condition of a downhole drill bit during drilling operations in a wellbore, or (3) a method of manufacturing an improved downhole drill bit. When characterized as an improved downhole drill bit, the present invention includes (1) an assembly including at least one bit body, (2) a coupling member formed at an upper portion of the assembly, (3) at least one operating conditioning sensor carried by the improved downhole drill bit for monitoring at least one operating condition during drilling operations, and (4) at least one memory means, located in and carried by the drill bit body, for recording in memory data pertaining to the at least one operating condition. Optionally, the improved downhole drill bit of the present invention may cooperate with a communication system for communicating information away from the improved downhole drill bit during drilling operations, preferably ultimately to a surface location. The improved downhole drill bit of the present invention may further include a processor member, which is located in and carried by the drill bit body, for performing at least one predefined analysis of the data pertaining to the at least one operating condition, which has been recorded by the at least one memory means.

Directional multi-blade boring heads (1000, 1050) are disclosed which have first and second blades (1030, 1032) which each define a deflecting surface (1036, 1038) for deflecting the boring head when the head is advanced without rotation. At least one intermediate blade (1034) extends between the deflecting surfaces in a three blade design. In a four blade design, a second intermediate blade (1042) extends on the side opposite the first intermediate blade (1034). The boring head is particularly effective in drilling a straight borehole through a variety of soil conditions when the boring head is simultaneously rotated and advanced along the direction of boring.

A two-cone earth boring bit having non-opposite cones that minimize the tendency for off-center rotation or rough running. The bit is composed of two cones, each having a cantilevered bearing shaft (19) with an axis extending inwardly and downwardly. A rotatable, generally conical cutter (21, 39) is mounted on each bearing shaft, each cutter having a conical gage surface to engage and define a borehole with a wall (29) of select gage diameter. The axis (37) of one cutter is skewed relative to the other (43) to cause the conical gage surface (35, 41) of the two cones to engage the wall of the hole at points (A, B) that are other than 180 degrees apart as compared to nonskewed cutters. These points are separated by a distance less than the selected gage diameter. A line between these points is separated from a line extending from one point through the rotatable axis (47) on the bit by a selected angle (α). The body of the bit and/or stabilizers are separated from the wall of the hole by a distance less than the selected gage diameter. A line between these points is separated from a line extending from one point through the rotatable axis on the bit by a selected angle. The body of the bit and/or stabilizers are separated from the wall of the borehole by a distance in a range from preferably one-fourth to one inch.

A rotary bit having a pair of semi-spheres (18, 20) rotatable about a shaft extending from a center tongue (14). The semi-spheres include a plurality of cutters (22, 24) arranged in a predetermined fashion to maximize cutting efficiency. The semi-spheres may be disposed slightly off-center from the bit's axis of symmetry to bias the bit in a particular direction.