Chemical Cutters for Stuck Tubing or Drillpipe

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The chemical cutter is a tool designed to cut and allow retrieval of stuck tubing or drillpipe in a well. The primary advantages of this tool over explosive methods are its ability to sever tubing without causing the following undesirable problems:

  • damaging the well casing or adjacent tubing
  • enlarging or leaving a burr on the OD of the cut.

In addition to cutting, the tool can be adapted to perforate one to four holes in the same plane to establish circulation or equalise pressure.

Safety Precautions

The chemical cutter, when used and handled properly, is a safe tool; however, like any oilfield pipe cutting device, when safety procedures and precautions are not observed, the tool can become dangerous. Always adhere to contractor procedures.

The following safety precautions shall be observed when preparing and running a chemical cutter:

  • As the chemicals are extremely dangerous, no personnel other than wireline service personnel who are fully trained in handling the chemical cutting tool shall be allowed to handle the tool.
  • Radio silence should be obtained before arming the chemical cutter.
  • Personnel handling the chemical cutter either before or after firing shall only handle the tool when wearing rubber gloves and goggles or face shield.
  • The protective sleeve is an aluminium sleeve that covers the lower half of the tool from the middle of the chemical cylinder to the bull plug. The protective sleeve shall always be used over the tool and shall be secured with the three allen screws provided.
  • The cutter must not be in the lubricator during pressure testing operations. The maximum allowable surface pressure for a low pressure cylinder tool is 1000 psi and 4500 psi for a high pressure cylinder tool.
  • It is critical that the well information given to the service company is accurate. If tubing weights or fluid data are not correct problems may be experienced in recovering the tool from the well.
  • The chemical cutters will not work in gas, therefore it should be ensured that there is a maximum of 100 ft of fluid above and below where the cut is to be made.
  • The maximum allowable clearance between the cutting head and the tubing to be cut should be no greater than 1/4in per side.

Comments  

#1 Fernando Da Silva 2015-07-16 12:01
how to assembly the chemical cut tools ?
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