Geology Reference
In-Depth Information
Figure 4.25 Rotary
drilling above fatal
Road, Hong Kong.
Polymer foam
(white) is being
used as the drilling
ush to try to
improve recovery.
Figure 4.26 Sample obtained from single-barrel Russian well drilling rig, El Hadjar steelworks,
Annaba, Algeria (see preface). Previous logging of similar samples had interpreted the layering as
some kind of varved sequence of silt and sand. Actually, the horizon in situ is fairly uniform
weathered (grade IV) gneiss (the pale material). The dark-brown silt horizons represent occasions
when the Algerian driller, bored with the slow drilling progress from his worn-out bits, raised the
drilling mud, which then became baked by the heat from the drilling process
…
The thickness of the
pale layers are an indication of the driller
'
s boredom threshold
-
generally pretty consistent.
ows
between the core and the core barrel and can wash away some of the
cored material, but it is still used internationally because it is relatively
inexpensive and can be mass produced. The problems can be reduced by
using a triple-tube system. In this system, the core enters a split inner
problem with the double-tube system is that the
flushing medium
