Patent ID: 7860693

Claim:
A method for determining bit walk rate of a long gage rotary drill bit comprising: applying a set of drilling conditions to the bit including at least bit rotational speed, rate of penetration along a bit rotational axis, and at least one characteristic of an earth formation; applying a steer rate to the bit by tilting the bit around a fulcrum point located on a sleeve located above the bit gage, wherein the fulcrum point is defined as a contact point between the sleeve and a wellbore; simulating, for a time interval, drilling of the earth formation by the bit under the set of drilling conditions, including calculating a steer force applied to the bit and an associated walk force; calculating a walk rate based at least on the steer force and the walk force; repeating the simulating successively for a predefined number of time intervals; and calculating an average walk rate of the bit using an average steer force and an average walk force over the simulated time interval.