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Rotary Drilling Method
In the rotary
method of drilling, action is accomplished by rotating a
drill pipe by means of a power driven rotary table or
hydraulic powered top head drive, with a bit attached to
the bottom of the pipe. The bit cuts and breaks up the
material as it penetrates the formation. Drilling fluid
for mud is pumped through the rotating drill pipe and
through holes in the bit. This fluid swirls in the
bottom of the hole picking up material broken by the
bit, then flows upward in the space outside the drill
pipe, carrying the cuttings to the ground surface and
clearing the hole.
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greater the fluid flow the faster the drilling. The
drill pipe and bit move downward deepening the hole as
the operation proceeds. At the surface, drilling mud
flows into a ditch to a settling pit where the cuttings
settle to the bottom. From the settling pit the fluid
overflows into another pit from which it is picked up
through the suction hose of the mud pump and re -
circulated through the drill pipe. In the rotary
drilling method the casing pipe is not introduced until
after the drilling operations are completed. The walls
of the hole are held in place by the pressure of the mud
pump against the sides of the hole.
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