Drilling fluid
in rotary serves two main purposes:
(i)
Facilitates
the rotation of drilling
tube during rotary drilling;
(ii)
Acts as a
cooling agent to cool down heat
generated during drilling operation.
Water is normally
employed as drilling fluid. However, it suffers from the
following drawbacks:
(i)
Water
affects the stability of
nearby ground with the
introduction of water
into the
borehole (borehole for soil; drillhole for rock);
(ii)
Water
affects the quality
of sample by
changing the water
content of soil
samples collected from the borehole/drillhole.
Substitutes are
available in market to replace water as drilling fluid (e.g. white
foam).
