Any object dropped or stuck in a well that interferes with it's normal operations is called a fish and must be removed from the well. The operation of removing these objects is called a fishing job. When we are involved in a fishing job, we simply say – "We are fishing".
Why or when these terms were first used, no one seems to know, but there are some similarities. We use a long line (the work string). The fish cannot be seen, but we do have to catch it (engage it) before the fish can be pulled out. I cannot think of any better terms, so let's go fishing.
Fishing jobs are put into two classifications, open hole and cased hole. When there is no casing in the area of the fish, it is called open hole fishing. When the fish is inside casing, it is called cased hole fishing. There are numerous kinds of fishing jobs. Wash over job, overshot run, spear run, stripping job, jar run, --that's just a few.
There are many things that can become a fish -- stuck drill pipe, broken drill pipe, drill collars, bit, bit cones, hand tools dropped in the well, sanded up or mud stuck tubing, packers become stuck, and much more. Wire line broken or stuck in open hole or cased hole can create a bad fishing job. There are many other things that can develop into a fish and many other causes that create a fishing job that haven't been mentioned here.
Since there is so many different kinds of fish and fishing jobs, there are many different tools and methods to do the job. Some of the tools are very simple and some are very complex.
There are no two fishing jobs alike, yet there are lots of fishing jobs similar. An experienced fishing tool man will draw from the experience he has gained on each job.
It is very important on a fishing job for all parties involved to cooperate with each other. It is important for the fishing tool people to obtain all the information concerning the well. That way they can can select the right tools and methods to clean the well out as quickly as possible.