Page 188 - Drilling Technology in Nontechnical Language

Chapter 8 – DIRECTIONAL AND HORIZONTAL DRILLING 179

aligning the bit in the desired direction and pumping hard without rotating,
the well can be deviated.
After washing away 5 or 6 ft, the bit is rotated and drilled conventionally.
The procedure can then be repeated as necessary, until about 12° of angle
is built up or until the rock becomes too firm to jet. A rotary build drilling

assembly is used (fig. 8–3) so that once some angle is achieved, the well
can continue to build angle while drilling and rotating.

Fig. 8–3. Jetting to deviate

In the right conditions, jetting can be the fastest and cheapest way to
kick off the well.

Whipstock

After drilling the well to the kickoff point, the bit is pulled out of the
hole. A whipstock is a wedge that is set in the hole. The fat edge of the
wedge is on the bottom of the hole. The drillstring is rotated and lowered.
Forced against the side of the hole, it starts to cut out of the original hole.

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