Patent ID: 8210288
Filing Date: 2012-07-03
Classification: E21B

Abstract:
1. A rotary drill bit operable to form a wellbore comprising: a bit body having one end operable for connection to a drill string; a plurality of cutting elements disposed on exterior portions of the bit body; the cutting elements defined in part by a respective substrate, a respective layer of hard cutting material disposed on one end of the respective substrate and a respective longitudinal bore extending through the respective layer of hard cutting material and into the respective substrate; a primary cutting surface disposed on an extreme end of each layer of hard cutting material opposite from the respective substrate; a respective protector inserted into the respective longitudinal bore and extending from the primary cutting surface of each cutting element; each respective protector extending from the primary cutting surface of the respective substrate and having a non-circular cross section; a secondary cutting surface formed on an extreme end of each respective protector opposite from the associated primary cutting surface; the respective protectors operable to control depth of cut of the associated cutting elements into adjacent portions of a downhole formation; and wherein the depth of cut is based on the formula: Δ corresponds with the designed depth of cut by the primary cutting surface of the cutting element; D corresponds with an effective diameter of the cutting element; d corresponds with an effective diameter of the respective protector; L corresponds with a length of the respective protector extending from the primary cutting surface of the cutting element; and β corresponds with a backrake angle of the cutting element.