Patent ID: 9650836
Date: 2017-05-16
CPC Classifications: E21B

Claim:
1. An earth-boring tool, comprising: a body comprising a crown at a leading end of the body, the crown comprising a cone region at and around a rotational axis of the body, a nose region adjacent to and surrounding the cone region, a shoulder region adjacent to and surrounding the nose region, and a gage region defining a periphery of the body adjacent to and surrounding the shoulder region; a first cutting element located in the cone region secured to the body, the first cutting element comprising a first polycrystalline table comprising interbonded grains of superhard material formed using a catalyst material and secured to a first substrate; a second cutting element located in the nose region secured to the body, the second cutting element comprising a second polycrystalline table comprising interbonded grains of superhard material formed using a catalyst material and secured to a second substrate; a third cutting element located in the shoulder region secured to the body, the third cutting element comprising a third polycrystalline table comprising interbonded grains of superhard material formed using a catalyst material and secured to a third substrate; and a fourth cutting element located in the gage region secured to the body, the fourth cutting element comprising a fourth polycrystalline table comprising interbonded grains of superhard material formed using a catalyst material and secured to a fourth substrate; wherein the first polycrystalline table is substantially free of the catalyst material to a first depth, the second polycrystalline table is substantially free of the catalyst material to a second, greater depth, the third polycrystalline table is substantially free of the catalyst material to a third, still greater depth, and the fourth polycrystalline material is substantially free of catalyst material to a fourth, greatest depth, and wherein a rate at which depth increases from the first depth, through the second and third depths, to the fourth depth is at least substantially according to a Solow growth curve.