Drill bit having optimised side rake angle

摘要

A method for designing a fixed cutter drill bit includes simulating the fixed cutter drill bit in an earth formation. A performance characteristic of the simulated fixed cutter drill bit is determined. A side rake angle distribution of the cutters is adjusted at least along a cone region 641 of a blade of the fixed cutter drill bit to change the performance characteristics of the fixed cutter drill bit. The drill bit produced by the invention comprises cutters positioned along a blade of the drill bit in a cone region 641 and cutters positioned along the blade in a nose region 642, wherein the cutters in the cone region 641 towards a centre of the drill bit have larger side rake angles than the cutters positioned along the nose region 642. The simulation may include calculating wear pattern on the cutters. The simulation is done without constraining a centreline of the drill bit to be coaxial with a centre line of a bore hole.