Definition - What does Casing Overshot mean?
A Casing Overshot is a tool that is joined to a drill pipe or tubing to act as a fishing tool. This tool is dropped inside the wellbore or lowered out of the wall pipe. Also known as an overshot, this tool uses a gripping device that holds the pipe firmly so that fish can be pulled out of the wellbore. A Casing Overshot is basically used as a pulling tool to pull a small fish neck while ensuring that the tool grabs it firmly, without slipping it off.
Petropedia explains Casing Overshot
A Casing Overshot tool is used mainly for fishing, i.e., to pull out or lower fish neck inside tubing or a large pipe. This tool basically consists of a bell, top sub and housing – the three components that help in latching the fish neck inside any size bore. It is a conventional downhole pulling tool that is primarily used in the fishing operations. The bell is installed on the bottom of the Casing Overshot to reduce the chances of travelling beyond a particular distance while fishing. Due to its design, operators can easily use the pulling tool to manage the operation.