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DRILLING OCEAN
|N California, U.S.A., the Rincon oil field extends out into the ocean. Until
recently, oil wells were drilled from piers, but the new method of slant hole or
directional drilling has made possible the recovery of oil from the ocean from a considerable
distance beyond the ends of the long ocean piers.
As a ship can'be navigated from its home port to distant harbors, it is also possible
to control the course of drilling so that locations several hundred feet away and
not directly beneath the hole at the surface may be reached with accuracy.
When the steel derricks over the old wells were removed, the extra room thus provided was used for
new well locations to be drilled by a portable machine capable of handling 200,000 pound loads. •
To prevent contamination of the ocean while drilling, a steel conductor pipe 20 inches in diameter
is sunk vertically into the water and then driven into the shale beds 45 feet below the surface. Top of
this conductor is then welded into the bottom of an 8-foot open-top tank built into the pipe, uruung
operations are carried on through this pipe. Further protection, both to the sea and to the on sanas
is provided by cementing into the hole a smaller casing extending from the well-head througti tne con-
ductor pipe to the cap-rop overlying the oil zone.
According to the Vacuum Oil Co., in drilling deviated wells it ftas
been the practice to drill a straight hole to a depth of from 1000 to
1500 feet and then to start the directional control. A long steel wedge
called a whipstock is lowered to the bottom and faced in the desired
direction. ,
Bit as it drills by the wedge is thus crowded from the vertical
and in the proper direction. Deviation from the vertical is very slight
at first, but by proper selection of the weight of the drilling tools on
bottom, type of bit and speed «f rotation of the bit, the angle is gradually
increased to the desired amount and the correct direction maintained.
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