| 摘要 |
<p>A partially diamond-enhanced drill bit includes a bit body, at leats one annular row of non-diamond enhanced buttons mounted in the bit body, and at least one annular row of diamond-enhanced buttons mounted in the bit body radially outside of the non-enhanced buttons. A total wear volume of the non-enhanced buttons in at least one row thereof is greater than 75 percent of a total wear volume of an outermost annular row of enhanced buttons. A number of non-enhanced buttons in one of the rows thereof is at least equal to a number of enhanced buttons in the outermost annular row thereof. At least some of the non-enhanced buttons have a greater wear volume than any of the enhanced buttons. The radially outermost row of non-enhanced buttons is displaced axially forwardly with respect to an adjacent row of enhanced buttons.</p> |
