Page 189 - Drilling Technology in Nontechnical Language

180 Drilling Technology in Nontechnical Language Second Edition

After drilling below the whipstock, the bit is pulled out of the hole
again. The whipstock is pulled out with the assembly. At the surface, the
whipstock can be removed. The drilling assembly is run back in. The ledge
at the bottom of the hole will be worn and cut away as operations continue.
Whipstocks are also used to deviate the well out of casing (fig. 8–4).

Instead of a drill bit, a mill is used that can cut metal. In this application,
the whipstock is left in place to guide tools through the cut in the casing.
The drillstring will bend to allow the bottomhole assembly to go
around the curved hole.

Fig. 8–4. Whipstock to deviate

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