SPWLA Glossary

Any kind of debris, extraneous to the formation, and that has become detached from some part of equipment used in an operation on a well and has become lodged or lost in some part of the borehole or borehole wall. Junk may be a lost bit, pieces of a bit, milled pieces of pipe, wrenches, or any relatively small object that impedes drilling. It often obstructs casing, tubing. or open hole and must be fished out. See also fish.