Patent ID: 7860696
Filing Date: 2010-12-28
Classification: E21B

Abstract:
1. A computer implemented method for determining bit walk characteristics of a rotary drill bit comprising: applying a set of drilling conditions to the bit including a rate of penetration along a bit rotational axis, at least one characteristic of an earth formation, and at least one characteristic of a wellbore formed by the rotary drill bit; applying a steer rate to the bit by tilting the bit relative to a fulcrum point located uphole from the bit; 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, an associated walk force and an associated walk angle; calculating a walk rate based at least on the steer force and the walk force; repeating the simulating and the calculating the walk rate steps successively for a predefined number of time intervals; calculating an average walk rate and an average walk angle for the bit over the simulated predefined number of time intervals; and outputting the calculated average walk rate and the average walk angle on a computer display and saving them in a computer file as determined bit walk characteristics of the rotary drill bit.