Polycrystalline diamond compact and applications therefor

A method of fabricating a polycrystalline diamond compact, comprising:

• enclosing a combination in a pressure transmitting medium to form a cell assembly, wherein the combination includes:
• a substrate including an interfacial surface;
• a lower region including a plurality of diamond particles positioned at least proximate to the interfacial surface of a substrate, the plurality of diamond particles of the lower region exhibiting a lower average particle size;
• at least an upper region including a plurality of diamond particles positioned adjacent to the lower region, the plurality of diamond particles of the at least an upper region exhibiting an upper average particle size that is at least twice, to about 3.5 times greater than, that of the lower average particle size;
• and
• subjecting the cell assembly to a high-pressure/high-temperature process to form a polycrystalline diamond table integrally with the substrate from the combination;
• and
• wherein the lower average particle size is at least about 60 μm and the upper average particle size is less than about 40 μm.

A rotary drill bit, comprising:

• a bit body including a leading end structure configured to facilitate drilling a subterranean formation;
• and
• a plurality of cutting elements mounted to the bit body, at least one of the plurality of cutting elements including:
• a polycrystalline diamond table including:
• a single lower region including a plurality of bonded diamond grains exhibiting a lower region average grain size;
• and
• at least an upper region directly bonded to the single lower region, the upper region at least partially defining at least one upper exterior surface of the polycrystalline diamond table, the upper region including a plurality of bonded diamond grains exhibiting an upper region average grain size of less than about 40 μm, the lower region average grain size being about two times to about 3.5 times greater than that of the upper region average grain size and at least about 60 μm;
• and
• a substrate including an interfacial surface that is directly bonded to the single lower region of the polycrystalline diamond table, the substrate being separated from the upper region by the single lower region.

A polycrystalline diamond compact, comprising:

• a polycrystalline diamond table including:
• a single lower region including a plurality of bonded diamond grains exhibiting a lower region average grain size of about 60 μm to about 80 μm;
• and
• at least an upper region directly bonded to the single lower region, the upper region including an upper surface at least partially defining at least one upper exterior surface of the polycrystalline diamond table, the upper region including a plurality of bonded diamond grains exhibiting an upper region average grain size of about 15 μm to about 35 μm;
• and
• a substrate including an interfacial surface that is bonded directly to the single lower region of the polycrystalline diamond table, the substrate being separated from the upper region by the single lower region.