ROTARY DRAG BIT AND METHODS THEREFOR

摘要

A rotary drag bit includes a primary cutter row (141) comprising at least one primary cutter, and at least two additional cutters configured relative to one another (19, 20, 21). In one embodiment, the cutters are backup cutters of a cutter group located in respective first and second trailing cutter rows (153), oriented relative to one another, and positioned to substantially follow the at least one primary cutter The rotary drag bit life is extended by the backup cutter group, making the bit more durable and extending the life of the cutters In other of the embodiments, the cutters are configured to selectively engage a subterranean formation material being drilled, providing improved bit life and reduced stress upon the cutters Still other embodiments of rotary drag bits include backup cutter configurations having different backrake angles and siderake angles, including methods therefor.