Patent ID: 8397562
Filing Date: 2013-03-19
Classification: E21B,G01V

Abstract:
1. A method for sensing the bending applied to a drill bit coupled to a drill string operating down hole in a well, comprising the steps of: a) rotating said drill string, said drill string having a plurality of pockets formed therein in each of which is located a set of strain sensors connected by circuitry so as to form a bridge, wherein each of said sets of strain sensors is affixed to a wall of its respective pocket, each of said sets of strain sensors comprising first, second, third and fourth strain sensors circumferentially spaced approximately equidistantly around said wall of its respective pocket, and wherein: b) applying a voltage across one of first and second pairs of terminals formed by circuitry connecting each of said strain sensors in said sets, said circuitry forming a bridge, said bridge comprising first, second, third and fourth legs, and wherein: wherein said third and fourth junctions form said second pair of terminals; c) sensing a voltage across the other of said first and second pairs of terminals; d) determining said bending on said drill bit from said sensed voltage.