| In
an attempt to eliminate the costs and risks associated with drilling
new wells, a new generation of small-diameter, steerable, hydraulic
motors were designed to fit inside existing well casings including
7", 5 1/2" and 4 1/2" casings (the smallest well casing, but used
extensively). Slimhole steerable motors are attached to flexible
drill pipe and lowered inside the existing casing, where a section
or "window" has been milled out of the lower section of
casing. The motors are set at a prescribed angle to "kick-off"
from a cement plug set in the window cut into the casing. This allows
the drilling assembly to exit the vertical casing and commence drilling
a predetermined 90 degree radius arc, designed to enter the top
of the horizontal payzone beyond the drainage pattern of the original
well. A horizontal hole measuring up to 5,000 feet or more is drilled
through the potentially productive section of the payzone allowing
for the recovery of oil and gas from a significantly greater drainage
area than would be possible by drilling a new vertical well.
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| Deep
well drilling platform like these Warren uses in its Texas and
California basins. |
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