Rolling cone bit with gage and off-gage cutter elements positioned to separate sidewall and bottom hole cutting duty

• Main Authors: Portwood, Gary Ray, Garcia, Gary Edward, Minikus, James Carl, Nese, Per Ivar, Cisneros, Dennis, Cawthorne, Chris Edward
• Format: Patent
• Language: English
• Published: 28.01.2003

The invention relates generally to earth-boring bits used to drill a borehole for the ultimate recovery of oil, gas or minerals. More particularly, the invention relates to rolling cone rock bits and to an enhanced cutting structure for such bits. Still more particularly, the invention relates to the placement of cutter elements on the rolling cone cutters at locations that increase bit durability and rate of penetration and enhance the bit's ability to maintain gage. A rolling cone bit includes at least one cone cutter having a gage row of cutter elements and a first inner row of near but off-gage cutter elements that are positioned so as to divide the sidewall and bottom hole cutting duty so as to enhance bit durability, maintain borehole diameter and improve ROP. The off-gage distance of the first inner row of cutter elements is defined for various bit sizes to optimize the division of cutting duty. The distance that the first inner row of cutter elements are off-gage may be constant for all the cones on the bit or may be varied among the various cones to balance the durability and wear characteristics on all the cones of the bit.