Drilling

Augar Drilling :-

                   Augers are hand-held or truck-mounted 
drills,which have rods with spiral flights to bring soft

material to the surface. They are used particularly

to sample placer deposits. Power augers

are particularly useful for deep sampling in

easily penetrable material where pitting is not

practicable (Barrett 1987). They vary in size

from those used to dig fence post holes to large,

truck-mounted rigs capable of reaching depths

of up to 60 m, but depths of less than 30 m are

more common. Hole diameters are from 5 to

15 cm in the larger units, although holes 1 m

in diameter were drilled to evaluate the Argyle

diamond deposit in Australia. In soft ground

augering is rapid and sampling procedures need

to be well organized to cope with the material

continuously brought to the surface by the

spiralling action of the auger. Considerable care

is required to minimize cross-contamination

between samples. Augers are light drills and are

incapable of penetrating either hard ground or

boulders. For this purpose, and holes deeper

than about 60 m, heavier equipment is necessary

and this is described in the next section.



Drilling Other :-
          For anyone interested in understanding the

subsurface, drilling is the most frequently used

technology. The various methods of drilling

serve different purposes at various stages of

an exploration program (Annels 1991). The

Australian Drilling Industry Training Committee

(1997) gives a comprehensive account of

methods, applications, and safety issues. Early

on when budgets are low, inexpensive drilling is

required. The disadvantage of cheaper methods,

such as augering, rotary or percussion drilling,

is that the quality of sampling is poor with considerable

mixing of different levels in the hole.

Later, more expensive, but quality samples are

usually collected using reverse circulation or

diamond core drilling