The Lifting-Lower and Releasing Overshot is a professional fishing tool designed for retrieving fractured tubing, drill pipe, and other tubular fish inside casing strings. The tool is particularly effective when conventional fishing operations become difficult due to heavily stuck fish or restricted downhole conditions.
Unlike standard overshots, this tool does not require drill string rotation during fishing or releasing operations. Fish engagement and release are achieved simply through controlled lifting and lowering motions of the drill string, significantly simplifying field operations.
The tool assembly consists of:
-
Top Sub
-
Bowl
-
Guide Pin
-
Guide Sleeve
-
Joint Sleeve
-
Plug
-
Roller Pin
-
Slip
-
Guide
The bowl contains an internal cone that matches the slip assembly to provide secure fish engagement. The guide sleeve features specially milled long and short track trenches that control fishing and release operations:
-
Long Trench → Fishing Position
-
Short Trench → Release Position
During operation, the guide pin moves between the trench positions through lifting and lowering actions, allowing the slip to either engage or release the fish without rotation.
The joint sleeve utilizes a two-petal structure connected through roller pins, while the slip assembly incorporates internal fish threads to ensure secure gripping performance.
Key Features
-
Non-rotational fishing operation design
-
Fishing and release through lifting and lowering only
-
Long and short trench guiding mechanism
-
Secure slip engagement system
-
Durable heavy-duty downhole construction
-
Efficient release mechanism for stuck fish
-
Reduced operational complexity
-
Reliable performance in difficult fishing environments
Applications
-
Fractured Tubing Fishing
-
Drill String Retrieval
-
Downhole Fishing Operations
-
Workover & Well Servicing
-
Non-Rotational Fishing Applications
-
Stuck Pipe Recovery
-
Tubular Recovery Operations
-
Well Intervention Services
Working Principle
The tool performs fishing and release operations through a guided trench mechanism:
-
When the guide pin enters the long trench position, the tool engages the fish.
-
When the guide pin enters the short trench position, the tool releases the fish.
As the tool reaches the fish top, lifting and lowering actions move the guide pin between trench positions, enabling secure fish engagement or controlled release without rotating the drill string.
Advantages
-
Eliminates the need for drill string rotation
-
Simplifies fishing and release operations
-
Reduces operational time and complexity
-
Reliable release capability for stuck fish
-
Lower risk of damaging the fish or casing
-
Efficient performance in difficult well conditions
-
Durable and rugged tool construction
-
Improved operational safety during fishing operations
