Collar seating type downhole throttling device

The slip-type downhole choke which is commonly used in the Sulige Gas Field is complex in fishing and unfreezing technologies and its success rate of fishing is low for the tubing is bitten by some slips. In this regard, the anchoring mode and structural characteristics of existing downhole tools were investigated and a collar seating type downhole throttling device was designed. By virtue of this new device, the setting is realized using adont claw, combined with tubing-collar clearance, and no specific unfreezing is needed in the process of fishing. And it is advantageous with easy unfreezing, free tubing and downslide prevention. Then, the actual borehole pressure and temperature were simulated by means of the finite element analysis method. In addition, stress analysis and design optimization were conducted on the core component of the collar seating type downhole throttling device, i.e., the claw anchoring mechanism. After the success of laboratory experiments, this kind of downhole throttling device was applied on site in 38 wells. Fishing was conducted in 10 wells after production was carried out for a while. It is shown that collar seating type downhole throttling device provides stable setting, reliable sealing and convenient fishing with the success rate of 100%.