What does downhole operation include（2）?

1. Well fall type

According to the name and nature of falling objects, the types of falling objects in wells mainly include: pipe falling objects, pole falling objects, rope falling objects and small pieces of falling objects.

2. Salvage of pipe fallen objects

Before fishing, one should first grasp the basic data of oil and water wells, that is, understand the drilling and oil production data, find out the structure of the well, the condition of the casing, and whether there are early falling objects. Secondly, find out the cause of the falling objects, whether there is any deformation and sand surface burial after the falling objects fall into the well. Calculate the maximum load that can be achieved while fishing, reinforce the derrick and guyline pit. It should also be taken into consideration that after catching the fallen objects, there should be preventive and anti-jamming measures in case of jamming underground.

Commonly used fishing tools include female cones, male cones, fishing spears, slip fishing barrels, etc.

The salvage steps are:

(1) Lower the lead mold for underground visits to understand the position and shape of the falling objects.

(2) According to the falling objects and the size of the annular space between the falling objects and the casing, select the appropriate fishing tools or design and manufacture the fishing tools yourself.

(3) Write construction design and safety measures, and carry out salvage treatment according to the construction design after approval by relevant departments according to the reporting procedures, and draw schematic diagrams for the tools for going into the well.

(4)The operation should be stable when fishing.

(5)Analyze the fallen objects salvaged and write a summary.

3. Pole drop fishing

Most of these falling objects are sucker rods, and there are also weighted rods and instruments. Falling objects fall into the casing and fall into the oil pipe.

(1) Fishing in the tubing

It is relatively simple to salvage the broken sucker rod in the tubing. For example, when the sucker rod is tripped, the sucker rod can be lowered to catch or lower the slip canister to salvage.

(2) Fishing in the casing

Fishing in the casing is more complicated, because the inner diameter of the casing is large, the rods are slender, the steel is small, easy to bend, easy to pull out, and the shape of the falling well is complicated. When salvaging, it can be salvaged with a hook to guide the shoe slip overshot or a loose-leaf overshot. When the falling object is bent in the casing, it can be salvaged with a fishing hook. When the falling objects are compacted underground and cannot be fished, use a casing milling cylinder or a milling shoe to grind, and use a magnet fisher to fish for debris.

4. Small items salvage

There are many types of small falling objects, such as steel balls, jaws, gear wheels, screws, etc. Although such falling objects are small, they are extremely difficult to salvage. The tools for salvaging small and fallen objects mainly include magnet salvage, grab, reverse circulation salvage basket and so on.