DA-B Safety Joint

The new DA-B safety joint integrates the functions of Big John jar and RTTS safety joint, and reserves a fishing interface. It is a new tool. When the tool is in the initial state, the jarring function and safety function are locked by the pull sleeve. At this time, the tool can normally transmit torque without affecting the use of the tool requiring torque operation.
When the DA-B safety joint needs to be operated in case of downhole sticking or other accidents, the string shall be lifted up first to break the pull sleeve. At this time, the tool is in the unlocked state, that is, the jarring function and the safety reversing function are released. The string can be jarred and unblocked with the jarring function first. When in use, the pulling force is applied to lift the string. Then when the drill pipe in the string is stretched to accumulate energy, the pulling force on the jar is suddenly released and the string shrinks, An impact will act on the stuck tool, and play the role of upward shock. If multiple jars are required, the jar can be operated repeatedly and the above process can be repeated to obtain.
If the jam still cannot be released after multiple shocks, the tool can be operated to unscrew and pull out the pipe string above the safety joint. At this time, it is only necessary to lift the pipe string to the end of upward jarring, then rotate the pipe string to the right, cut off the torsional shear pin on the tool, continue to maintain the lifting state and rotate the pipe string to the right, and then the reverse thread release function can be realized.

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