Methods and systems may be provided for simulating forming a wide variety
of directional wellbores including wellbores with variable tilt rates
and/or relatively constant tilt rates. The methods and systems may also
be used to simulate forming a wellbore in subterranean formations having
a combination of soft, medium and hard formation materials, multiple
layers of formation materials and relatively hard stringers disposed
throughout one or more layers of formation material. Values of bit
steerability and controllability calculated from such simulations may be
used to design and/or select drilling equipment for use in forming a
directional wellbore.