Back Off Procedure

Drill pipe or drill collars can be unscrewed downhole by exploding a charge inside a selected tool joint connection, close to the stuck point.

Requisites for a successful back-off are the following:

  • There must be sufficient minimum inside diameter.
  • The charge must be accurately placed across the connection.
  • There must be sufficient string shot strength (Refer to table 16.a).
  • Neutral or slightly positive tension is applied at the back-off point.
  • Sufficient left hand torque must be applied at the back off point.

As a general rule, the first attempt to back-off should be made at the first connection above Free Point. If there is a failure, the second attempt should be performed on the first stand above the Free Point. Subsequent attempts should be made moving upward one stand at a time.

To ensure a safe operation, the Company Drilling and Completion Supervisor shall carry out the following checks:

  1. Ensure that tong and slips dies are clean, sharp and the proper size for the string above the rotary table.
  2. The tongs, snub and jerk lines are in working condition.
  3. The slip handles are tied together with strong line, to prevent the slips being kicked out of the table when the pipe break out.
  4. The elevators are latched around the pipe and loose under a tool joint with the hook locked when torque is being applied to the string.
  5. Ensure that no resilient torque remains in the string when it is picked up out of the slips, unless the pipe is properly held with a back-up tong.
  6. A wireline cutter must be on the rig floor during the entire operation.

A detailed standard back-off procedure cannot be used as there are too many variables. The following is a typical generic procedure:

  1. Keep non-essential personnel off the rig floor.
  2. Install one or two Kelly Cocks on the pipe above rotary the table.
  3. If it is required due to hole conditions, install a stuffing box and pump in sub.
  4. Tighten up all string connections applying right hand torque (max. 80% of nominal value). The torque should be worked down the string. This procedure should be repeated 4 to 5 times especially in crooked or deviated holes.
  5. Install the back-off tool in the string and run in the hole to around 150-300ft (50-100m) below the rotary table.
  6. Pick up the string to have a hook load equal to the weight, in air, of the pipe above the selected back-off point, plus 10 to 15%.
  7. Apply left hand torque in a series of steps. Work the pipe at each step to transfer the torque downhole.

ENI S.p.A. Agip Division

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Responses

  • nieve
    How to do mechanical back off?
    3 years ago
  • Gabriel Halvorson
    How to latch right hand tong on pipe?
    3 years ago
  • DAVID
    How to back off joint drill pipe?
    1 year ago
  • milo
    How to wireline backoff?
    1 year ago
  • marino
    What does it take to back a joint out drilling?
    1 year ago
  • SADOC
    What is a string shot for mechanical back off?
    1 year ago
  • panu
    How to back off the drill string?
    11 months ago
  • impi
    How does a back off charge work drilling?
    11 months ago
  • priamus
    How to make a wireline stringshot?
    9 months ago
  • Natalia
    How to perform a blind backoff with drill pipe?
    8 months ago
  • DODERIC
    How to string shot a stuck drill string?
    5 months ago

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