When abandoning an oil or gas well, performing salvage operations, or facing situations with low fluid levels, heavy drilling mud, or cost constraints, operators often turn to a specialized tool called the explosive jet cutter or jet cutter in short. This shaped charge device runs on an electric wireline and is designed to sever pipes in a controlled and efficient manner.
The jet cutter’s plastic explosive features a modified parabolic face with a circular shape that conforms to the pipe it needs to cut. This unique design allows for a precise and focused detonation.
Upon detonation, the shaped charge explosive flares the cut end of the pipe. To facilitate the subsequent fishing or retrieval of the severed pipe section, it is necessary to remove this flared portion. Typically, this can be accomplished during the same operation by employing a mill guide or a hollow mill container with an insert. These tools are run on the bottom of an overshot fishing tool and, through rotation, can dress off the flared or burred end, allowing the overshot to slip over the fish (severed pipe section) easily.
This image below shows how the tubing was cut with the explosive jet cutter.
Tubing cut with the jet cutter
It is important to note that there is a slight risk of damaging adjacent strings or casings if they are in contact with the pipe at the cut point during the detonation.
Jet cutters are available for a wide range of pipe sizes, including tubing, drill pipe, and casing. For particularly challenging fishing operations involving drill pipe and drill collars, operators may opt for larger jet cutters known as severing cutters. These cutters create an even more significant flare, making it challenging to dress off the top of the severed section, especially in open holes. Severing charges are placed across tool joints rather than within the pipe’s tube itself.
Overall, jet cutters offer a reliable and cost-effective solution for cutting pipes during well abandonment, salvage operations, or when other cutting methods are impractical or uneconomical.
References
The Guide to Oilwell Fishing Operations: Tools, Techniques, and Rules of Thumb (Gulf Drilling Guides) by Joe P. DeGeare, David Haughton, Mark McGurk
