ARPO
ENI S.p.A. Agip Division
PAGE
IDENTIFICATION CODE
202 OF 234
REVISION STAP-P-1-M-6140
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Methods of Freeing Pipe 1) 2) 3) 4) 5)
Work the pipe applying cyclic slack-off and overpull combined with torque. Always check the reduction in the pipe yield stress due to the application of the torque. Spot oil-base mud, or oil containing a surfactant around the drill collars. Reduce the mud weight, if possible. Use a drilling jar/bumper. Conduct a DST procedure.
Note: 16.2.
Quick actions are fundamental in freeing the wall of stuck drill pipe, since the problem gets worse with time.
STICKING DUE TO HOLE RESTRICTION Causes The most common causes of hole restriction: • • •
Too thick a wall cake due to the use of high solids /high filtrate mud in front of porous and permeable formations. Swelling of formations containing clay. Extrusion of gumbo shale into the wellbore in underbalance situations.
Preventive Measures Problems are usually suspected by increase in drag during connections. Once the cause is recognised to be any of the three previously listed, the following actions should be undertaken: 1) 2) 3) 4) 5)
Reduce mud filtrate, cake and solids content. Use inhibited mud. Increase mud weight. Increase mud clearing capacity. Increase flow rate.
In all situations, frequent wiper trips can reduce the problem and provide information on the severity. Methods of Freeing Pipe 1) 2) 3) 4)
Work the pipe applying slack-off if the string has become stuck pulling out, and overpull if it stuck while running in. Spot a cushion to break and remove the mud cake around the drill collars. Increase the mud weight, if possible. Use a drilling jar/bumper.