Page 243 - Drilling Technology in Nontechnical Language

234 Drilling Technology in Nontechnical Language Second Edition

▪ Explosive sidewall coring
▪ Rotary sidewall coring
Each of these is described in more detail.

Bottomhole coring

A special drill bit (usually a PDC type but can be diamond) with a hole
in the center cuts a doughnut-shaped hole. The column of rock sticking up
inside the core bit is protected by an arrangement of tubes. When coring
is complete, the coring assembly is pulled out to the surface, and the core
itself is held within. This is the most expensive type of coring but gives the

most useful sample for analysis (fig. 10–3).

Fig. 10–3. Bottomhole core sample

_Devereux_Book.indb 234 1/16/12 2:12 PM