Page 391 - Practical Well Planning and Drilling Manual

Section 3 revised 11/00/bc 1/17/01 12:00 PM Page 367

3.3.4
Drilling Problems [ ]

Pick up with the elevators to a weight equal to the block + weight
in air of the string above the stuck point. Mark the string level with the
rotary table. Pick up another 20-40 k lbs and make another mark on
the pipe. Set the slips with the minimum of downward string move-
ment and tie the handles together to prevent the slips from being
thrown across the floor if they should come out. Lock the block. Dress
the backup tong to fit around the pipe body and check that the dies are
clean and sharp.
With the rotary table apply left-hand torque to the string—about
half the DP connection make-up torque. Count the number of turns.
Lock the table with the rotary brake, then put the breakout tong on the
pipe, a couple of feet above the table. Make the tong bite, take up some
tension on the breakout line with the cathead, then carefully release
the rotary lock. Allow the breakout cathead to come back so that the
pipe tension is held by the backup line without shock loading it.
Keep everyone clear of the drillfloor. With the table fully unlocked,
carefully pick up the pipe to release the slips. This ensures that the
slips are not holding any torque when the crew pull them. Now send
two crew members to untie and pull the slips, avoiding standing
behind the tong. Stand the slips out of the way of the tong.
Work the torque down the string by moving the pipe up as far as
the tong line, or pipe tension allows, and back to the lower line marked
on the pipe earlier. Do not lower the string beyond this line until ready to
backoff. Monitor the pull on the tong-line gauge; the tension should
drop as torque is worked down the string. When the line tension does
not decrease further, set and tie the slips with the pipe lowered to the
lower line. Take a pull with the breakout cathead and then lock the
table so that the tong can be unlatched. Remove the tong.
Apply more torque and work the string as before, increasing the
torque each time until after three or four times you have worked in
about 50% of drillpipe make-up torque but left-hand into the string.
For instance, if the drillpipe tool joint make-up torque is 20,000 ft/lbs,
aim to work in about 10,000 ft/lbs of left-hand torque. Keep a count of
the total number of left-hand turns in the string. If the rotary table
stalls out or cannot be controlled finely enough, take a bite with the
tong, pull the tong, lock the table, move the tong back for another bite,
etc., until enough torque is in the string.
Once enough left-hand torque is worked in, lower the string until
the upper of the two lines is at the rotary table.

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