Definition - What does Fishing Tool mean?
Fishing Tool is a specialized tool which is used to retrieve a dropped object from the wellbore. The dropped object may be drilling equipment like drill string, casings and drill bits. The Fishing Tool may also be required to retrieve older well equipment like packers, liners, tubing or any stuck object in the well. It is mandatory to retrieve these pieces of equipment from the wellbore so as to continue will the drilling operations.
Petropedia explains Fishing Tool
During any stage of operation, rig operators encounter unexpected situations like falling of drill string, stuck pipe, loss of bit etc., in the well. The piece of equipment that falls in the well is called “fish” or “junk” and the tool employed to remove them is known as a Fishing Tool.
Fishing Tools are classified as outside grappler, which surround the fish and grab it from the outside area and carry it up to the wellbore. Over shots falls in this category. The inside grappler is tapered in design with thread profiles which are able to move inside and thread the fish top enabling the fish to be recovered. Spears, taper mills fall in this category. Force intensifiers catch the fish on the top by means of pulling the fish. Jars falls in this category.
Other tools include wash pipe or washover pipes which are used when the tool is unable to grip the fish with a cutting surface. Impression block made of soft metal is run in the hole with a drill pipe to the top of fish which provides impression of the fish top upon inspection at the surface enabling the selection of proper tool for fishing. The selection of the type of tool depends on the type of fish in the well.