In the oil field, any piece left in a well is called fish that prevents the execution of subsequent operations. This definition covers all the stages of drilling, record taking or production (maintenance, completion, repair), which includes drill bits, pipes, records acquisition tools or any other metal element that It could have been lost, damaged, stuck, dropped or left in the well. A fishing job is defined as the set of operations or procedures made in the well in order to recover a fish that we prevents or affects the continuity of the operating program of a drilling well.
Fishing operations can be presented at any time of life productive of a well; from the drilling stage to the abandonment stage. To carry out these operations, we have various tools and methods that can be applied to different types of fish classes, depending on whether the fish is free or stuck, in addition to considering the area where the fish is located, in an open hole or in a cased hole and the diameter. A fishing job should be an economic solution to a problem in the well, the decision to proceed with fishing should be considered in terms of the need to preserve the well, recover expensive equipment or comply with the normative. In turn, each decision will be charged with costs, risks and repercussions.
Probable causes that cause us a fish while drilling a well
The fishing term is historically taken from the beginning of drilling with cable tool. At that time, when a steel line broke, a member of the team simply put a hook on a line and tried take the steel line to retrieve the tool or the fish. The necessity and ingenuity brought these workers from the oil field to develop new hooks. The trial and error methods of the beginning of the industry built the basis for many of the used fishing tools to this day.
Fishing tool companies have advanced at the same pace as with the rapid development of the oil industry and the deployment of new technology. Today many are able to fish successfully in wells with depths that exceed 20,000 feet, at high angles of deviation, in wells horizontal and deep water.
Fishing problems:
A fishing problem is defined as the set of operations or procedures performed within a well with the objective of removing or recover materials, tools or pipes that impede or affect development sequential during the intervention of the well. It is one of the most important problems that affect the development of intervention in a well. They can occur for several reasons, the most common are: the faults of some component of surface equipment, subsurface, accessories of work (keys, wedges, etc.) and, in some cases, due to bad operations made and human carelessness.
Fishing work:
Fishing jobs are classified in three ways: open hole, when not there is casing in the fish area; coated hole, when the fish is inside the casing; or through the pipe, when it is necessary to fish through the restriction of a diameter reduced pipe. The types of fishing in hole discovered and in hole tubing involve relatively common procedures, techniques and tools similar, but the problems and the danger is different.
The open hole works are more related to the operations of well drilling, are usually carried out with mud, so there is the risk of trapping the pipe due to the existence of differential pressure then this factor must always be taken into account. While the fishing work in tube holes is more related with the completion or maintenance of the well, in these cases the same is used tool the only difference is that it is smaller and the necessary forces they are minor.
Types of fishing according to the shape of the fish:
This division has been made to facilitate a bit the selection of tools already that there are a large number and variety of tools in the market with different names but that for the fishing problem are similar and have the same principles of operation. In the market there are several companies providers of specialized services in the field, in fishing tasks, essential is not to waste your time and if you do not have the appropriate tool at hand the rescue is delayed and therefore the costs increase.
It is divided into two parts:
- Garbage or Scrap Fishing: In the oil industry, usually a very common fishing job, after the tubular fish, any smaller object constitutes it that the diameter of the bowl of the main hub of the rotary table can get lost at the bottom of the well, as for example: the recovery of cones of augers, wedges, small tools, steel cables and miscellaneous metal parts that fall In the well.
- Pipeline Fishing: There are many factors that lead to the imprisonment of the string of drilling. When this happens, the most important thing is to identify the cause and type of imprisonment so that the most effective method can be used to overcome the problem.
CAUSES
* Failure in the pipe: Metal fatigue can cause the pipe, the drill collars or the casing to twist and / or break.
* Pipe Fitting: Tubing, drill collars, or coating that have been stuck may fail unexpectedly due to over stress during attempts to release the glue.
* Bit failure: A mechanical failure of the bit can cause cones, teeth or bearings to fall and fall into the well.
* Scrap in the Pit: Scrap as tools (keys, nuts and bolts) and other relatively small objects (such as wall-firing trigger elements) that may fall into the pit must be fished before further drilling.
*Broken log cable: If subjected to excessive loads, the log wire can be broken, with the consequent loss of tools and cable, which must be removed from the well before being able to continue recording or continue with any other drilling operation .
* Electric Cables: In addition to the basic tools that are used in cleaning wells we are also required to use a series of services with electrical cables such as:
- Free point detection
- Explosive rope
- Cutter to Jet
- Chemical cutter
* Detection of the Free Point: It is a special device that is inserted inside the pipe to know at what depth it is stuck. The device is introduced by means of a steel cable, which is measured as it decreases the readings of the electrical impulses from the contacts of the instruments can be observed on the surface. These impulses will vary when the contacts are above the grip point of the string, when the tube is subjected to tension or torsion stresses.
* Jet Cutter: It is an explosive cutting tool of molded load. The explosive force of the shot literally concentrates on the disintegration of the metal in the pipe to make a cross section.
* Chemical Cutter: It is an electrical device that uses a very strong acid discharge to make a smooth cut, without flange, or distortion of the metal.
CLASSIFICATION OF TOOLS BASED ON THE TYPE OF FISHERIES:
- Tubular pieces extraction tools.
- Tools for non-tubular fish.
- Fish destroying tools.
- Tubular pieces extraction tools.
ROLLERS OR HITCHERS FUNCTION
EXTERNAL GRIP TYPE
(DIE NECKLACE)
It is a simple fishing tool that grabs the tubular part on the outside, working in the form of a thread. The tool twists to the right and is released by rotating to the left, which is why it is rarely used because it does not come off easily and is not practical.
SHORT CATCH PESCANTE
It is a variety of "overshot" is used when the fishing points have a critical length (short). Unlike "overshot" it is only composed of a "bowl" and a "top sub". The internal configuration of the "bowl" is conical with spirals and at the moment of tension it contracts to adhere to the fish.
PLUG (OVERSHOAT)
It is a tool that grabs outside by wedges or claws that allow them to run on the tapered surface of the plug connector. The modern plug is removable, can be circulated through the fish, endures the traction, twisting and strokes necessary to loosen the fish. That's why the plug is the fishing tool that is most used in rescue work.
TYPE INTERNAL AGARRE
MACHO AGAINST (TAPER TAP)
It is a tool designed to grasp the inner part of the tubular fish, penetrates the tube by plowing (machining) thread in its path. Like the dice collar, the tapered male does not release the fish. Although still used in special tasks, the tapered male has been replaced almost entirely by various types of harpoons.
ARPON (Itco)
The Itco Type Harpoon is an internal trapping fishing tool designed to recover tubular members from the wellbore. It has wedges that hold the fish inside. It is removable and WO fluid can be circulated by the harpoon and by the fish. It can be operated in production tubing from 2 3/8 "to 4 1/2" or for coatings from 5 "to 9 5/8".
FISHING MAGNETS (PESCANTE MAGNET)
It is ideal to recover all types of Small objects that lie freely at the bottom of the well
BASKET FOR JUNK (JUNK BASKET)
A scrap basket is positioned immediately above the bit so that it picks up the scrap that could damage the bit. To collect the scrap that is at the bottom of the hole, the drill is lowered almost to the bottom, then the mud pumps are connected so that the flow picks up the scrap, and finally, the pumps stop so that the scrap falls inside the basket. This procedure is repeated several times and then, when removing the string, it is determined if all the scrap has been fished.
