Patent ID: 6547017
Filing Date: 2003-04-15
Classification: E21B

Abstract:
A method of drilling a relatively constant diameter borehole into a geological formation that has a variable hardness using a rotary drill bit attached to a rotary drill string including at least the following steps:(a) providing a rotary drill bit, whereby said rotary drill bit has a first self-actuating longitudinal compensation means within said bit that is actuated by any longitudinal bit wear, and whereby said rotary drill bit has a second self-actuating longitudinal compensation means within said bit that is responsive to the hardness of the geological formation, and whereby said rotary drill bit has self-actuating lateral compensation means within said bit that is actuated by any lateral bit wear, (b) attaching said bit to the rotary drill string on the surface of the earth; (c) drilling the borehole with said rotary drill bit attached to the rotary drill string, whereby the drilling rate at a specific depth from the surface of the earth is dependent upon the hardness of the geological formation at said specific depth; (d) compensating for any longitudinal bit wear of the drill bit by using said first self-actuating longitudinal compensation means; (e) compensating for any lateral bit wear of the drill bit by using said self-actuating lateral compensation means; and (f) compensating for the change in hardness of the geological formation using said second self-actuating longitudinal compensation means at a minimum of one particular depth from the surface of the earth to increase the drilling rate during the drilling of the borehole.