(I) Drill string assembly
Safety joint installs on the tubing string and operates for drilling, salvaging, well cleaning, repairing and testing, etc. Its diameter and diameter of the bit port should be the same as the matched string. Also the joint thread and the string are supposed to be matched in case changeover of plugs.
a. When in fishing operation, the safety joints are generally connected above the recovery tools (pins, boxs, fishing spear, basket, fishing cylinder, etc) and under the shock tool.
b. During the testing operation, the safety joints are connected above the geotechnical tester and the packer, under the shock tool.
c. While cleaning the well, it is connected between the well wash string and drill pipe.
d. When the safety joint used on a tubing string, it is attached to a tubing hanger or a packer.
(2) Operation
a. Check the O-rings before down-hole operation.
b. Tighten the wide saw-tooth threads to match the torque of the matched string.
c. Tighten the
threads of each pipe and record the weight of the pipe above the safety joint
when descending to a predetermined depth.
