Patent ID: 7729895

Claim:
A computer implemented method for determining steerability of a rotary drill bit comprising: (a) applying, using a computer, a set of drilling conditions to the bit including at least bit rotational speed, rate of penetration along a bit axis and at least one characteristics of an earth formation; (b) applying, using the computer, a steer rate to the bit; (c) simulating, using the computer, for a time interval drilling the earth formation by the bit under the set of drilling conditions including calculating a steer force applied to the bit; (d) simulating, using the computer, drilling the earth formation for another time interval and recalculating the steer force; (e) repeating, using the computer, simulating drilling the earth formation successively for a predefined number of time intervals; (f) calculating, using the computer, an average steer force applied to the bit over the simulated time intervals; (g) saving, using the computer, the applied steer rate and the calculated average steer force; (h) repeating, using the computer, within a predefined range of steer rates, steps (b) to (g) by incrementally increasing the bit steer rate; and (i) analyzing, using the computer, mathematically the average steer forces as a function of the applied steer rates and determining the steerability of the rotary drill bit based on the analysis.