The working principle and operation method of window overshot

1. Structure of windowed overshot

The window overshot is welded by two parts of the cylinder body and the upper joint (also threaded connection)

According to the salvage needs, the lower end of the cylinder can be made into the following four different structures:

(1) The spiral semi-oblique cut is easy to rotate and introduce the fish.

(2) The zigzag milling shoe cut is convenient for set milling to clean the hard objects on the top of the fish and guide the fish into it.

(3) The bell mouth of the inner cone is convenient for direct introduction of fish.

(4) A grab-shaped cutout Combine a grab with a windowed overshot to increase the fishing effect.

2. Working principle of window overshot

When the fish enters the cylinder and pushes into the window tongue, the window tongue expands outwards, its rebound force bites the body of the fish tightly, and the window tongue also firmly clamps the steps, that is, the fish is caught.

3. Working method of window overshot

(1) Check whether the threads or welds of each part are intact and firm. Measure whether the size of the window tongue and the minimum inner diameter of the closed state can fit the fish, and keep the picture for further investigation.

(2)Drill down to 2~3m above the top of the fish, and start the pump to wash the well. Slowly rotate the drill string to lower it. Observe the change of the weight scale and the square entry, remember to touch the fish to enter, and guide the cylinder to enter the fish.

(3)Continue to lower the drill string to make the fish enter the inner cavity of the tool barrel. If the length of the falling objects is short, the well is deep, and it is difficult to judge the square entry and the change of the suspension weight, the drill string can be lifted by 1-2m after one fishing, and then rotated and lowered. Repeat several times to lift the drill.

(4) When lifting the drill, it should be operated smoothly. Do not touch the fish and hit the drill string suddenly, so as not to shake the fish down and fall into the well again.