In accordance with one embodiment of the present invention, a method for drilling
a lateral wellbore from a slant well includes drilling the slant well below the
surface of the earth such that the slant well is angled toward a first horizontal
direction that coincides with a desired drilling direction for the lateral wellbore.
The slant well has a borehole wall that includes a high side portion closest to
the surface, a low side portion farthest from the surface, and two side portions
between the high side portion and the low side portion. The method further includes
disposing a casing string in the slant well, disposing a drill string having a
bent sub, a mud motor, and a drill bit coupled at a lower end thereof in the casing
string, and positioning the drill bit adjacent either one of the side portions
or the low side portion. The method further includes drilling, from either the
side portion or the low side portion, an intermediate wellbore with the drill bit,
and drilling, from the intermediate wellbore, the lateral wellbore in the desired
drilling direction.