1.
n. [Formation Evaluation]
Another term for corkscrew hole, the result of certain drilling conditions that cause the
borehole to take the shape of a corkscrew. Most
logging tools are much longer than the wavelength of the corkscrew, and therefore see it as a change in
standoff or a change in hole size. For this reason, the corkscrew is often observed as a
wave on the
caliper log. A corkscrew hole affects measurements sensitive to standoff, such as
induction and
neutron porosity, and may affect
pad tools, if they cannot follow the changes.