Downhole Debris Fishing and Stuck Drilling Accident Treatment

1.Downhole debris Fishing

1.1 Type of downhole fall

According to the name and nature of the falling objects, the types of falling objects in the mine are mainly: pipe falling objects, rod falling objects, rope falling objects and small pieces falling objects.

1.2．Pipe falling objects

Before fishing, the basic data of oil and water Wells should be mastered first, that is, the drilling and oil production information should be understood clearly, the structure of the well, the casing situation, and whether there is early falling object. Secondly, find out the cause of falling objects, whether there is deformation and sand surface buried after falling into the well. Calculate the maximum load that can be achieved when fishing, reinforce the derrick and the man rope pit. It should also be considered that after catching the fallen objects, if the underground card should have prevention and reconciliation measures.

Common fishing tools : Die collars, Taper taps, Spear, Slip Overshot and so on.

Fishing Procedure:

⑴Downhole visitation of the Impression Blocks to NOTE the position and shape of the falling objects.

⑵According to the situation of falling objects and the size of the Annular space between falling objects and casing, choose the appropriate fishing tools or design and make fishing tools by yourself.

⑶Prepare construction design and safety measures, and after approval by relevant departments in accordance with the reporting procedures, Fishing treatment shall be carried out according to the construction design, and sketch drawings shall be drawn for downhole tools.

⑷Fishing operation should be smooth.

⑸Analyze the Fished objects and write a summary.

1.3．Rod falling objects

Most of these falls are rod types, and there are also weight rods and meters. Some fell into the casing, some fell into the tubing.

⑴Fishing in tubing

It is relatively simple to fish the broken rod in the tubing, such as the rod can be pulled down when the rod is pulled out of the buckle or the slip dredging drum for fishing, if not fished, you can also carry out the tubing operation.

⑵Fishing in casing

Casing fishing is more complicated, because the casing diameter is large, the rod is slender, the steel is small, easy to bend, easy to pull out, and the shape of falling well is complex. When fishing, it can be fished with lifting hook guide shoe slip overshot or loose-blade Fishing device. When the falling object is bent in the casing, it can be retrieved with a fishing hook. When the debris is compacted in the hole and cannot be retrieved, it is milled with a sleeve mill or a shoe mill, and debris is recovered with a magnet catcher.

1.4．Fishing of small pieces

There are many types of small pieces falling, such as steel balls, pliers, cones, screws and so on. Such debris is small but extremely difficult to recover. The main tools for fishing small pieces are magnet fishing device, grab, reverse circulation fishing basket and so on.

2.Stuck Drilling Accident Treatment

There are many reasons for stuck drilling, so there are many types of stuck drilling. Common sand Stuck, wax stuck, falling object stuck, casing deformation stuck, cement solidification stuck and so on.

2.1．Sand Stuck Treatment

If the sticking time of tool is not long or the sand jam is not serious, the pipe string can be lifted up and down to loosen the sand and relieve the drilling jam accident.

For the treatment of serious sand stuck Wells, first, the load is increased slowly when the load reaches a certain value, and the load is immediately lowered and quickly unloaded. Second, after a period of up and down activities, the pipe string is tightened to stop, so that the pipe string is suspended for a period of time under the stretching condition, so that the tension gradually spreads to the lower pipe string. Both forms may work, but each activity should be stopped for 5 to 10min for a period of time to prevent the string from fatigue and break.

The sand stucking can also be treated by the methods of compression reverse circulation release, washpipe release, strong lifting release, jack release, reverse casing milling release,and so on.

2.2．Falling object sticking treatment

Falling object sticking means that pliers teeth, slip teeth, other small tools fall into the well and get stuck, resulting in stuck drilling.

Dealing with falling objects stuck drilling, do not vigorously lift, in order to prevent stuck, causing complications. There are two general treatment methods: If the stuck string can be turned, it can be gently lifted and slowly turned. The falling material is crushed to make the underground pipe string unstuck; If the above method is ineffective, the wall hook can be used to correct the top of the fish, and then Refish the drop

2.3．Remove casing stuck

Due to increasing production measures or other reasons, the casing is deformed or damaged, and the downhole tool is mistakenly lowered over the damaged area, resulting in stuck drilling. During processing, the pipe column above the stuck point should be removed and the stuck can only be released after the casing is repaired.