Abstract: The fixed cutter drill bit disclosed utilizes a unique piloting section and reaming section carefully designed to impart several specific operational advantages. In the piloting section, cutting structures have been arranged so as to create offsetting cutting forces that result in a net zero imbalance during operation. Furthermore, the piloting section utilizes carefully placed shock studs which aid in protecting the primary cutting structure. In addition, the location of the fluid supply nozzles on the body of the reamer section serves to indicate the occurrence of a catastrophic cutting structure failure below the pilot gage.

Abstract: A drill out bi-center bit and a method for using the same are provided that offer the ability to drill out cement and casing shoes, and increased stability. The bi-center bit includes a bit body having a first end operable to be coupled with a drill string, a second end including a pilot section, and an eccentric reamer section intermediate the first and second ends. A first plurality of cutter assemblies is disposed upon the exterior surface of the pilot section, while a second plurality of cutter assemblies is disposed upon the reamer section. A plurality of recessed cutter assemblies is also disposed upon the pilot section, such that the recessed cutter assemblies are located within a radius beginning at a central axis of the pilot section and terminating at a central axis of the reamer section and are recessed with respect to a lower surface of the pilot.

Abstract: A percussion drill bit is provided that has at least two different pluralities of inserts extending from the bit head to better match the conditions seen on the bit head during drilling. The preferred embodiment has a plurality of large inserts with a polycrystalline diamond layer located at least in the gage row and a plurality of smaller inserts located at least in the inner rows.

Abstract: A cutting element for a drag-type drill bit comprises a cutter body having a generally cylindrical base section adapted for snug-fitting engagement in a socket of a drill bit body. The cutter body is secured to the bit body by brazing or other conventional attachment techniques. The cutter body further has a generally cylindrical cutting section integral with the base section. The cutting section has at least one inclined surface extending from a top surface of the cutting section partially along the length of the generally cylindrical cutting section. The cutter body may comprise a sintered tungsten carbide and the top surface may comprise a layer of super hard material.

Abstract: A drill out bi-center bit and a method for using the same are provided that offer the ability to drill out cement and casing shoes, and increased stability. The bi-center bit includes a bit body having a first end operable to be coupled with a drill string, a second end including a pilot section, and an eccentric reamer section intermediate the first and second ends. A first plurality of cutter assemblies is disposed upon the exterior surface of the pilot section, while a second plurality of cutter assemblies is disposed upon the reamer section. A plurality of recessed cutter assemblies is also disposed upon the pilot section, such that the recessed cutter assemblies are located within a radius beginning at a central axis of the pilot section and terminating at a central axis of the reamer section and are recessed with respect to a lower surface of the pilot.

Abstract: A cutting element for a drag-type drill bit comprises a cutter body having a generally cylindrical base section adapted for snug-fitting engagement in a socket of a drill bit body. The cutter body is secured to the bit body by brazing or other conventional attachment techniques. The cutter body further has a generally cylindrical cutting section integral with the base section. The cutting section has at least one inclined surface extending from a top surface of the cutting section partially the length of the generally cylindrical cutting section. The cutter body may comprise a sintered tungsten carbide and the top surface may comprise a layer of super hard material.

Abstract: A drag type casing mill/drill bit for down hole milling of a casing window and lateral drilling of a bore hole in an earth formation comprises a bit body adapted to be rotated in a defined direction. The bit body includes an operating end face having a plurality of radially extending blades formed as a part of the operating end face of the bit body. A plurality of primary cutting elements are individually mounted in pockets in one of the plurality of blades. In addition, a plurality of secondary ridge structures are mounted to each of the plurality of blades interspersed with the plurality of primary cutting elements in a pattern such that as the bit body rotates the secondary ridge structures contact the casing or the earth formation thereby protecting the primary cutting elements and allowing continuous substantially smooth casing milling and earth formation drilling.

Abstract: A fixed cutter drill bit particularly suited for plastic shale drilling includes rows of cutter elements arranged so that the cutting tips of the cutters in a row are disposed at leading and lagging angular positions so as to define a serrated cutting edge. The angular position of the cutting tips of cutters in a given row may be varied by mounting cutters with different degrees of positive and negative backrake along the same blade. Preferably, within a segment of a given row, the cutters alternate between having positive backrake and negative backrake while the cutters mounted with positive backrake are more exposed to the formation material than those mounted with negative backrake. Nozzles are provided with a highly lateral orientation for efficient cleaning. The positive backrake cutter elements have a dual-radiused cutting face and are mounted so as to have a relief angle relative to the formation material.

Abstract: A drag type casing mill/drill bit for down hole milling of a casing window and lateral drilling of a bore hole in an earth formation comprises a bit body adapted to be rotated in a defined direction. The bit body includes an operating end face having a plurality of radially extending blades formed as a part of the operating end face of the bit body. A plurality of primary cutting elements are individually mounted in pockets in one of the plurality of blades. In addition, a plurality of secondary ridge structures are mounted to each of the plurality of blades interspersed with the plurality of primary cutting elements in a pattern such that as the bit body rotates the secondary ridge structures contact the casing or the earth formation thereby protecting the primary cutting elements and allowing continuous substantially smooth casing milling and earth formation drilling.

Abstract: A percussion drill bit is provided that has at least two different pluralities of inserts extending from the bit head to better match the conditions seen on the bit head during drilling. The preferred embodiment has a plurality of large inserts with a polycrystalline diamond layer located at least in the gage row and a plurality of smaller inserts located at least in the inner rows.

Abstract: A fixed cutter drill bit particularly suited for plastic shale drilling includes rows of cutter elements arranged so that the cutting tips of the cutters in a row are disposed at leading and lagging angular positions so as to define a serrated cutting edge. The angular position of the cutting tips of cutters in a given row may be varied by mounting cutters with different degrees of positive and negative backrake along the same blade. Preferably, within a segment of a given row, the cutters alternate between having positive backrake and negative backrake while the cutters mounted with positive backrake are more exposed to the formation material than those mounted with negative backrake. Nozzles are provided with a highly lateral orientation for efficient cleaning. The positive backrake cutter elements have a dual-radiused cutting face and are mounted so as to have a relief angle relative to the formation material.

Abstract: A supporting substrate for supporting a diamond layer on a cutting element is disclosed which has an irregular surface defining the interface between the substrate and the diamond layer. The irregularities in the surface may have varying amplitudes, varying frequencies, or both and can vary according to defined mathematical expressions. The irregularities may assume recognizable geometric forms, such as spiral, circle or wave configurations, or may be arranged in an irregular manner. The surface is constructed with or without a plane of symmetry and may have different average amplitudes and/or frequencies in different areas.

Abstract: A drill bit adapted to walk predictably during drilling is disclosed, comprising: a bit body having a longitudinal axis and a bit face having an active zone and a passive zone, and a plurality of cutters on the bit face, a first portion of said cutters being positioned in the active zone and a second portion of said cutters being positioned in the passive zone, the first portion of cutters being more aggressive than the second portion. This the difference in aggressiveness of cutters in the first and second portions is achieved by maximizing the effect of one or more of seven features of the bit. These features include: cutter size, cutter tip profile, blade relationship, cutting structure, back rake, gage pad design and balance. Application of the principles of the present invention result in a large imbalance vector being oriented toward the leading half of the active zone.

Abstract: A supporting substrate for supporting a diamond layer on a cutting element is disclosed which has an irregular surface defining the interface between the substrate and the diamond layer. The irregularities in the surface comprise closed loops that may vary in amplitude, frequency or both. The irregularities may comprise ridges or grooves or a combination of ridges and grooves.

Abstract: Thin walled metal alloy receptacles are filled with a filler material. If granular, the filler material is solidified in the receptacles. The receptacles are inserted in a bit mold with their open ends abutting against preformed cutter locations in the bit mold. The mold is filled with a steel or tungsten carbide powder and a binder and exposed to temperatures sufficient to cause the binder to infiltrate the steel or tungsten carbide as well as infiltrate the receptacle outer surfaces, metallurgically bonding the receptacles to the binder. The mold is then removed, revealing a bit body with the bonded filled receptacles. The filler material is removed from the receptacles PCD cutters are inserted in the receptacles and are brazed using conventional brazing techniques.

Abstract: A fixed cutter drill bit includes cutter elements mounted in sets on the bit face. A cutter element set includes at least three cutters with cutting faces having at least two different curvatures. The cutter elements of the set are mounted on various blades of the bit such that, in rotated profile, the cutting profile of a larger and a smaller cutter element overlap, and such that the smaller cutter element is flanked by larger sized cutters. The bit exhibits increased stability, before and after wear has occurred. The large cutters provide for efficient shearing while the smaller cutters may provide prefracturing in certain formations.

Abstract: A fixed cutter drill bit and cutting structure are disclosed which include cutter elements having cutting faces with different abrasion resistances. The cutter elements are spaced apart on the bit face so as to provide a bit cutting profile having abrasion resistance gradients. As wear occurs, the cutting structure assumes a cutting profile that creates grooves and ridges in the formation material to provide enhanced bit stabilization. Regions of differing abrasion resistances may also be provided on the individual cutting faces to provide a cutting profile that enhances bit stabilization. Further, the cutting structure may include substrate members that support the cutting faces and that themselves are made of materials having differing degrees of abrasion resistance. Providing these regions of differing wear resistance along the bit face tends to increase the bit's ability to resist vibration and provides an aggressive cutting structure, even after significant wear has occurred.

Abstract: A fixed cutter drill bit includes a cutting structure having radially-spaced sets of cutter elements. Each cutter in a set has a cutting profile that, in rotated profile, partially overlaps the cutting profiles of each of the other cutters that are in the same set so as to create a region of maximum diamond density. The region of maximum diamond density in a set is defined such that the centerlines of the cutting profiles of the elements in the set pass through the region of maximum diamond density. The cutting profiles of the spaced sets of cutters also may overlap to create border regions of multiple diamond density. The diamond density of border regions is less than or equal to the density in the region of maximum diamond density. Providing such regions of varying diamond density along the bit face tends to increase the bit's ability to resist vibration and provides an aggressive cutting structure, even after significant wear has occurred.

Abstract: A fixed cutter drill bit includes sets of cutter elements mounted on the bit face, each set including at least two cutters that are mounted at generally the same radial position with respect to the bit axis. The cutter elements of a set are positioned on different blades of the bit and are mounted having their cutting faces are out-of-profile, such that certain elements in the set are exposed to the formation material to a greater extent than other cutter elements in the same set. The cutter elements in a set may have equal diameters or may vary in size. The bit exhibits increased stability or vibration resistance, and drills initially as a "light-set" bit and later as a "heavy-set" bit.

Abstract: A fixed cutter drill bit includes a cutting structure having radially-spaced sets of cutter elements. The cutter element sets preferably overlap in rotated profile and include at least one low profile cutter element and at least two high profile elements. The low profile element is mounted so as to have a relatively low exposure height. The high profile elements are mounted at exposure heights that are greater than the exposure height of the low profile element, and are radially spaced from the low profile element on the bit face. The high profile elements may be mounted at the same radial position but at differing exposure heights, or may be mounted at the same exposure heights but at different radial positions relative to the bit axis. Providing this arrangement of low and high profile cutter elements tends to increase the bit's ability to resist vibration and provides an aggressive cutting structure, even after significant wear has occurred.