, 1934-11-25

hETWAu SA8AA
Derrick-An elongated, pyramid
shaped structure Of either wood or
steel framework over an oil well
used to support drilling equipment,
hosting or lowering tools and
machinery. Derricks range IN
height, ordinarily, from 96 70 IA
feet.
Rig-Assemblage OF machinery
and tools for drilling an oil well,
including derrick and auxiliary
structures.
Rotary riga drilling rig which
digs a round hole In the earth by
rotating a hollow piple, known as
drill-stem or drill-pipe. to the
lower end OF which is attached q
bit, a tool which cuts into the
earth. Through the hollow drill
stem is circulated a composition
Of earth and water, known as
mud. This circulating mud brings
to the curface cuttings made In the
bottom Of the hole by the bit. AT
the same time, the rotary motion
Of the drill-tem plasters the walls
Of the hole with this mud 70 pre-
vent caving.
Drill stem or drill-pipe-As ex-
planned above. drill stem Is a hol-
low pipe used in drilling an oil
well. and Is comparable to an
auEer stem. The drill-stem with
the bit attached is comparable TO
the bit on q carpenters brace and
bit or wood-auger. Drill-tem Is
not an ordinary iron pipe. IL Is
made of the finest seamless alloy
heat-treated steel. 1t usually comes
Is 20-foot lengths. both ends OF
which are fitted with a specially
designed and threaded screw joint
known as q 'tooI-joint". AS drilling
progresses, joints Of drill-stem may
be added. one on top Of another
to the Joints already in the hole.
Single-One joint Of drill-stem.
Double-Two joints Of drill-stem
screwed together.
Thrlbble, treble, threble-Three
joints OF drill-stem screwed to-
gether.
FourbIe, forble-Four joints OF
drill stem screwed together. Most
rigs use either doubles or fcurbleS
in removing drill-stem from the
hole. These lengths are stacked
IN the derrick when not In the hole
and the use OF doubles or fouroles
depends sometimes upon the
height OF the derrick. sometimes on
the lifting power Of the machinery
used in drilling. sometimes on the
desires OF the driller.
Fourble- hoard. forble-board - A
platform built high IN the derrick
near the upper end Of a fourble 70
allow a man to attach elevators
to the fourble for lowering It into
the hole.
Draw-works-A drum or reel To-
Gated at one side Of the derrick
floor on which Is wound steel cable
used In lowering drill stem or
tools into the hole and removing
them. The reel is operated by q
powerful steam engine.
Crown-block-A series OF pulleys
set In a steel block at the top OF
the derrick. Gable from the reel
on the derrick floor passes through
these pulleys, Of which there are
several. and thence 70 the travel
ing block. Crown-block Is 30
named because Of its location at
the crown OF the derrick 10 diff
ferentiate from travelling block.
Travelling block-Another series Of
pulleys through which the steel
cabel passes. The cable runs from
the reel known as the draw-works
TO and through the crown-block,
thence down to the traveling-b block.
and down inside the derrick. hence
The traveling-block travels" Up
and down inside the derrick, hence
the name. To the lower end OF the
travelling block Is attached a hook
from which are suspended the kelly
joint and the elevators.
Kellyjoint-A tool restmbling a
joint Of drill-stem In size and length