"Gunner" wrote in message
...
On Sun, 29 May 2005 20:40:35 -0700, Ken Cutt
wrote:

Tom Miller wrote:
wrote in message
...

Oil rigs seem to be capable of drilling holes inches in diameter
and thousands of feet deep. They can keep these holes amazingly
straight or deliberately curve them.

How do they do this and what does the drill head look like?

Jim


I worked in the oil patch in Alberta in the 1960's & 70's. At that time
directional drilling was expensive and uncertain. Straight drilling was
done
by using very heavy "drill collars" at the bottom of the drill string.
The
bits were usually three steel cones with carbide buttons on them.The
cones
were mounted on bearings with the base of the cones just off the centre
line
of the drill and the point of the cone facing outward. Drilling mud was
pumped down the centre of the drill string,and the entire string was
rotated. The buttons on the bit broke up the rock and the chips were
flushed
up the annulus between the hole and the drill string. This mud was
allowed
to run over a "shale shaker" which separated any large chips. The mud
was
recirculated continuously. After a while the bit wear and drilling
would
slow. This meant that the entire drill string had to be pulled out,
unscrewed into 90 ft sections and stacked on end in derrick. In those
days
the deepest holes in Alberta were about 17,00 ft. It could take over 24
hours of heavy ,dirty work to replace a bit so bit quality was
paramount.
Directional drilling has matured enormously since then so I'm not
familiar
with present procedures


I also worked on rigs in Alberta in the 70's . Did lots of deep hole
directional drilling . Certainly in those days it was anything but
hi-tech . Three kinds of bits . Diamond used only when pulling core
samples . Toothed bits when the substrata was soft rock and button bits
when the rock was harder . When passing through strata the wrong style
bit pretty much stops progress so you have to pull the entire pipe out
and switch them . I never got as deep as 17,000 but 13,000 took about 17
hours round trip . Dangerous time . Every time the pipe is pulled a long
metal rod is dropped down the center of the drill stem . Inside is a
small compass and a point the punctures it to show the compass heading
at the bottom of the hole . If drilling is going smoothly and the pipe
is not pulled often the rod/compass is dropped down connected to a sand
line after it hits bottom it is winched back up before drilling can
proceed . If the bit has wandered to the right heading heavy thick pipes
(collars) are added right behind the bit to hold it at the desired
course . these do not flex so bore straight . In addition every so often
a specialty outfit is brought in with a contained compass and a camera .
Pictures are taken showing the heading at carefully monitored distances
. In addition every piece of drill stem in measured before it is added
to the string . With the compass shots and the exact lengths they know
very accurately where the bit is at any given depth . It is also sent to
the Gov . I know there was lots of talk in the real old days about slant
drilling but by the time I got on a rig it was pretty much over , at
least in the corner of the world I worked . I had friends that worked in
Indonesia and China , same there they told me . I never saw a gun or
heard of anyone shooting at anyone either . All I worked were
exploratory holes so what was found was of great interest to the
competition and yes there were spies to watch and film . That said if
oil was found everyone told everyone they knew . I doubt there was any
need to shoot at anyone to protect what would be common knowledge . Hey
maybe not ideal but try stop a batch of 20 year old kids when they know
something ;-) . 90 foot sections of pipe flex at least 10 feet when
racking them . So you worked on a triple , me too . There were at least
four quads in Alberta working when I was there so 120 pulls . In the
south hundreds of singles 30 foot pulls and doubles 60 foot pulls . I
never worked any small rigs but guys told me they would go on long
change and have to phone the office to find the new location . Those
rigs moved weekly . Where the big deep hole ones sat in one spot for 6
to 8 months .
Ken Cutt

High Kelly and a dull bit
Same old driller and the
Same old ****



I haven't heard the jingle for 30 years!


Gunner, triples, singles and gin poles.
Derrick, chain, pits and mud.



"Considering the events of recent years,
the world has a long way to go to regain
its credibility and reputation with the US."
unknown