What happens when something falls or breaks into a well hole (wellbore)? You go fishing!
Fishing in the oil and Gas industry is the application of tools, equipment and techniques for the removal of
Fishing Tool Schematic
junk, debris or ‘fish’ from a wellbore. The key elements of a fishing operation include an understanding of the dimensions and nature of the fish to be removed, the wellbore conditions, the tools and techniques employed and the process by which the recovered fish will be handled at surface.
A fish in this case is a term used for anything left in a wellbore which doesn’t belong there. It doesn’t matter whether the fish consists of junk metal, a hand tool, a length of drill pipe, drill collars, or an expensive Measurements While Drilling (MWD) tool (no relation to WMD), and directional drilling package. Once the component is lost, it is properly referred to as simply “the fish.” Typically, anything put into the hole is accurately measured and sketched so that appropriate fishing tools can be selected if the item must be fished out of the hole.
Junk is anything in the wellbore that is not supposed to be there. The term is usually reserved for small pieces of steel such as hand tools, small parts, bit nozzles, pieces of bits or other downhole tools. In short, junk is anything that doesn’t have much value but still needs to be fished out.
Fishing can take a day, a few days and even weeks. Losing things down a wellbore is very common. I’m currently on a location where a coil tubing unit lost a drill bit in the hole. Now the bit needs to be fished out. The longest fishing job I’ve been on lasted two weeks with no success in removing the object. The hole was abandoned and another drilled ten meters away. I’ve heard of fishing jobs that take months.
Fishing is done by a specialist called a fisherman. A fisherman can use various tools at his disposal and can even feel by touch whether the fish is caught or not. As the tool at the bottom of the pipe hits the fish, the soundwave can be felt at the top of the pipe and the fisherman makes slight adjustments to ensure the fish is secure before the pipe is brought back to surface. You never know whether the fish is caught until the pipe is pulled up. If unsecessful, the process repeats itself until the object is removed from the hole.
