Patent ID: 8145465
Filing Date: 2012-03-27
Classification: E21B

Abstract:
1. A computer implemented method for determining bit walk characteristics of a long gage rotary drill bit, including a gage pad having a first downhole end and a second uphole end 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 disposed between the downhole end and the uphole end of the gage pad; 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 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 storing the calculated average walk rate and the calculated average walk angle in a computer file as determined bit walk characteristics of the rotary drill bit.