The DLT-T Releasing Left-hand Overshot integrating various fishing overshot, box tap is a new type of fishing tool . It is not only used to retrieves pipe-shaped fishes such as drill pipe, oil tube , but also used to retrieve, back off, and release the fishes. The overshot can proceed the circulation of well liquid. In the course of fishing, the back-off overshot is an important mating tool, meanwhile, it can work with drill pipe. The overshot ' s allowed load not less than releasing overshot,and its performance far superior than box taper and other back-off tools.
Construction and operation
The DLT-T Releasing Left-hand Overshot consists of top sub, barrel body, slip, spring, spring seat, seal packer,and guide shoe. The top sub upper connect with drill pipe and other tools, and lower end links with barrel body, the spring embedded in the inner bore of the middle part. The barrel body has three control button maintaining a uniform distribution which control the position of the slip. The overall wall of the barrel body is thin-walled cylinder, and inner thread with both ends. There are also three buttons on the internal surface of cone under the barrel body, they stand opposite each other at a distance with the those mentioned above. The three buttons transfer the torque to the slip and complete reversing. The included angel of inner inclined plane restricts the way of compassion between the slip and the barrel body, and have the fish released.
