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.

Abstract: A fixed cutter drill bit includes sets of cutter elements mounted on the bit face. Each set includes at least two cutters mounted on different blades at generally the same radial position with reset to the bit axis but having differing degrees of backrake. The cutter elements of a set may be mounted having their cutting faces 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 cutting faces and profiles that are identical, or they may vary in size or shape or both. The bit exhibits increased stability and provides substantial improvement in ROP without requiting excessive WOB.