Fishing tools are the most widely used special tools for oil and water well overhaul construction with the largest number of times and the most complete varieties and specifications. There are many types and specifications of fishing tools in drilling. According to the types of falling objects in the well, they can be divided into five categories: pipe type fishing tools, rod type fishing tools, rope type fishing tools, logging tool type fishing tools and small object type fishing tools. If they are classified according to the structural characteristics of the types of fishing tools in drilling, they can be divided into cone type and spear type.
The cone type fishing tool is a kind of special tool which is specially used to catch the dropped object from the inner hole or outer wall of the pipe type. The fishing success rate is high and the operation is easy to master. The shortage is that once the fishing is stopped, it is difficult to pull out the tool. After the tool enters the fish cavity or the falling object enters the fishing cavity, it is better to increase the bit pressure and rotate the turning tool appropriately for forcing the fishing thread to squeeze the inner or outer wall of the falling object to make the buckle. When the buckle (generally more than 3 threads) can bear a certain lifting force and torque, lift the drilling tool and continue to make the buckle. After the buckle is made to 8-10 threads, the fishing thread and the dropped object are basically connected, and the buckle can be made. In general, the bearing force of the buckle can exceed the thread strength of the fished fish.
Spear fishing tools can be divided into three categories according to the structural characteristics of the tools: non retractable slide spear, coupling spear and retractable spear. Among them, the slide block bailing spear is divided into two kinds: single tooth block and double tooth block, and the coupling bailing spear is divided into rod coupling and tubing coupling bailing spear.