Multilevel force balanced downhole drilling tools and methods

摘要

Various downhole drilling tools designed and manufactured at least in part on evaluating respective forces acting on respective groups and sets of cutting elements during simulated engagement with the downhole end of a wellbore and drilling from a first downhole formation into a second downhole formation. Simulating forces acting on each cutting element as the cutting element contacts a downhole formation may be used to force balance downhole drilling tools during transition drilling or non-uniform downhole drilling conditions. Multilevel force balanced downhole drilling tools may be designed using five respective simulations, cutter group level, neighbor cutter group level, cutter set level, group of N (N=3 or N=4) consecutive cutters level and all cutters level. Various cutter layout procedures and algorithms may also be used to design multilevel force balanced downhole drilling tools which may drill faster with higher lateral stability, especially during downhole transiting drilling conditions.

主权项

1. A rotary drill bit designed and manufactured to form a wellbore in response to weight on bit (WOB) and torque on bit (TOB) applied to the rotary drill bit while forming the wellbore comprising:
a bit body with a bit rotational axis extending through the bit body; a plurality of blades disposed on exterior portions of the bit body; each blade having respective cutting elements disposed thereon; the cutting elements producing a bit axial force acting on the rotary drill bit, a bit lateral force acting on the rotary drill bit and a bit bending moment acting on the rotary drill bit while forming the wellbore; and the cutting elements disposed at respective selected locations on exterior portions of the blades operable to limit: maximum transient bit lateral imbalance force to less than approximately 8% of associated transient bit axial force; bit lateral imbalance force when all cutting elements are engaged with a generally uniform downhole formation to less than approximately 4% of bit axial force; maximum transient bit radial lateral imbalance forces to less than approximately 6% of associated bit transient axial force; bit radial lateral imbalance force when all cutting elements are engaged with a generally uniform downhole formation to less than approximately 2.5% of associated bit axial force; maximum transient bit drag lateral imbalance force to less than approximately 6% of associated bit transient axial force; bit drag lateral imbalance force when all cutting elements are engaged with a general uniform downhole formation to less than approximately 2.5% of associated bit axial force; maximum bit axial moment to less than approximately 15% of associated transient torque; and bit axial moment when all cutters are engaged with a generally uniform downhole formation to less than approximately 4% of associated bit torque.