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REVERSING SUB
REVERSING SUB
TIANHE-FT-RSUB
The reversing subs is also called reversing spear which is a special tool for reversing stuck drill stem above stuck point in drilling and workover operation. In treatment of stuck drill stem, it can work as a fishing pin tap in reversing operation. When fish is stuck or cannot be reversed in fishing or reversing operation, the fish can be reversed from reversing sub and the fishing drill tool is tripped out.
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Product Overview of the Reversing Sub

The reversing sub is a specialized downhole fishing tool used in petroleum drilling operations. The primary function of the reversing sub is to establish a connection with the fish (downhole junk) through specific mechanical structures, enabling the reverse buck-off of pipe strings. The reversing sub is an essential piece of equipment for handling downhole incidents, known for its efficiency and reliability.

Main Functions

  • Reverse Buck-Off Function: The reversing sub can perform reverse buck-off operations at a safe location when the drill string gets stuck, separating the drill string through surface operations.

  • Fishing Connection Function: After completing the reverse buck-off, the reversing sub provides a stable transition connection for subsequent fishing operations.

  • Safe Release Function: Advanced reversing subs are designed with a safety release mechanism, allowing safe disengagement through methods such as hydraulic pressure.

  • Circulation and Well Cleaning Function: The reversing sub retains a circulation channel, permitting drilling fluid to pass through for wellbore cleaning.

Technical Advantages

  • Efficient Incident Handling Capability: The reversing sub offers a controlled and safe method for downhole pipe string separation.

  • Strong Load Transmission Performance: Carefully designed, the reversing sub can withstand complex loads such as high tension and torque.

  • Flexible Retractable Design: Modern reversing subs feature an improved release mechanism, allowing safe withdrawal through specific operations.

  • Wide Applicability: The reversing sub is available in various specifications and models, suitable for different sizes of casings and drill pipes.

Application Scenarios

  • Stuck Pipe Incident Handling: The reversing sub is used to reverse and retrieve the non-stuck section of the drill string above the sticking point.

  • Fishing for Broken Drill Tools: The reversing sub is run into the fish to create a new engagement point internally or externally.

  • Operations in Complex Well Structures: Hydraulic reversing subs effectively handle incidents in complex well conditions such as multilateral wells.

  • Drilling Safety Assurance: Integrated into the drill string, the reversing sub enhances operational efficiency and safety.

Conclusion
The reversing sub is a vital technical product in the petroleum drilling industry. Selecting the appropriate reversing sub and using it correctly is key to successfully managing downhole incidents. The development of the reversing sub reflects the industry's continuous pursuit of operational efficiency and safety.