Product Name:fishing die
Product Model:
Place of Origin: Shanxi, China
1. Definition and Structure
Definition: A fishing die is a specialized tool used for threading and fishing operations on the outer walls of tubular fish such as drill pipes and oil tubes. It is suitable for cylindrical fish without inner holes or with blocked inner holes. In the petroleum industry, it is also known as a "fishing collar" and is an essential tool for fishing operations.
Structure:
Material: Made of high-strength alloy steel forgings, heat-treated for high strength and toughness.
Shape: Cylindrical integral structure, consisting of an upper joint and a main body.
Fishing Thread: Available in sawtooth and triangular shapes, with a surface hardness of HRC60~65. Cutting grooves are provided on the fishing thread to facilitate threading.
2. Purpose
Primarily used for threading and fishing operations on the outer walls of tubular fish.
Particularly suitable for cylindrical fish without inner holes or with blocked inner holes, such as drill pipes and oil tubes. It is also effective in complex well conditions for fishing operations.
3. Working Principle
Threading Mechanism: The fishing die relies on the fishing thread to bite into the outer wall of the fish under the action of drilling pressure and torque, thereby fishing out the fish. This process involves extrusion and biting without generating chips.
Operating Steps:
Lower the tool to 1~2 meters above the fish top (the top of the fish).
Start the pump to circulate fluid, lower the tool, and observe changes in pump pressure and hanging weight to force the fish top into the die collar.
Apply drilling pressure (generally 20~30kN) and rotate the tool at a speed of 10~20r/min to thread.
After threading for 5~10 turns, lift the tool. If the hanging weight increases, trip out; if not, repeat the above operations.
4. Application Scenarios
Advantageous Scenarios:
Fish Top Eccentric or Slip of Fishing Tap: When the fish top is eccentric or the fishing tap slips, the die collar has a larger contact area and can fish more effectively.
Damaged Fish Top: In cases where the fish top has been damaged after multiple unsuccessful fishing attempts, the die collar can successfully fish out the damaged fish top string.
Large Borehole and Small Pipe String: In well conditions with a large borehole and a small pipe string, the fishing tap may repeatedly fail to locate the fish top, while the die collar can catch the fish more effectively.
Scenarios Requiring Caution:
Open Hole or Severe Sand Production: In open holes or wells with severe sand production, the large outer diameter of the die collar may easily cause sticking.
Damaged Casing: In wells with severely damaged casing, special attention should be paid to prevent the die collar from getting stuck. If necessary, a safety joint can be connected above the die collar to facilitate tripping out the drill string in case of sticking.
5. Operating Precautions
Prevent Damage: During fishing, avoid bumping the fish top to prevent damage to the fish top or fishing thread.
Safety Joint: Before lowering the tool into the well, a safety joint should be connected above it to facilitate tripping out the drill string above the safety joint if necessary.
Use of Guide Shoe: When fishing for fish with a small outer diameter, a guide shoe should be added to prevent incorrect threading positions.
Summary
The die collar is an efficient and specialized tool for oil well workover operations, particularly suitable for fishing operations on the outer walls of tubular fish. Through its unique working principle and structural advantages, it can achieve effective fishing in various complex well conditions. In actual operations, it is necessary to reasonably select and use the die collar according to specific well conditions and fish characteristics, and strictly follow operating procedures to ensure operation safety and efficiency.