In the oil and gas industry, circular tubes refers to very long metal pipes, usually 1 to 3.25 in (25 to 83 mm) in diameter provided spool on large reel. These are used for intervention in oil and gas wells and sometimes as production tubes in depleted gas wells. Coiled tubing is often used to perform surgery similar to a cable. The main benefit of wireline is the ability to pump chemicals through the coil and the ability to push them into the hole rather than relying on gravity. Pumping can be quite self-contained, almost closed system, because the tube is continuously instead of jointed pipes. For offshore operations, the 'footprint' for circular tube operations is generally larger than wire deployment, which can limit the number of installations in which rolled tubes can be performed and make operations more expensive. A rolled tube operation is usually done through derrick drilling on an oil platform, which is used to support surface equipment, although on a platform without a stand alone drilling facility can be used instead. For the operation of a circular tube at an undersea well, a cellular offshore drilling unit (MODU) eg. semi-submersible, drillship etc. should be used to support all surface equipment and personnel, while wireline can be done from smaller and cheaper intervention vessels. On land, they can be run using a smaller service rig, and for light operation, self-use circular tubing rigs can be used.
String tools at the bottom of the coil are often called bottom hole assembly (BHA). This can range from something as simple as a jetting nozzle, to a job involving pumping chemicals or cement through a coil, to a larger string logging tool, depending on the operation.
Coil tubing has also been used as a cheaper version of operation operation. This is used for open pit drilling and milling operations. Common circular steel pipes have yield strengths ranging from 55,000 PSI to 120,000 PSI so that they can also be used to break up reservoirs, a process in which fluids are pressed up to thousands of psi at a particular point in a well to break the stone and allow product flow. Coil tubing can perform virtually any operation for oil well operation if used properly.
Video Coiled tubing
Usage
Circulation
The most common use for rolled tubes is circulation or deliquification. Hydrostatic head (liquid column in drilled well) may inhibit the flow of formation fluid due to its weight (the well is said to have been killed). The safest (though not the cheapest) solution is to try to remove fluids, using gases, often nitrogen ( Often called 'Teka Nitrogen' ). By running the tube rolled into the bottom of the hole and pumping in the gas, the killer fluid can be forced out for production. Circulating can also be used to clean out the remnants of light, which may have accumulated in the hole. Coiling tubing umbilicals can deliver hydraulic submersible pumps and jet pumps into wells. This pump allows the cleaning of low and non-invasive wells in low-pressure CBM (coal bed methane) wells. These Umbilicals can also be run into horizontally and laterally distorted wells.
Pumping
Pumping through rolled tubes can also be used to disperse liquids to specific locations in wells such as for cementing perforations or to perform chemical downhole components such as sandscreens. In the first case, the rolled tube is very advantageous rather than simply pumping the cement from the surface as it allows it to flow through all the potentially damaging solutions of important components, such as the downhole safety valve. Coiled tubing umbilical technologies allow the deployment of complex pumps requiring lots of fluid strings on a rolled pipe. In many cases, the use of rolled tubes to deploy complex pumps can greatly reduce dispersal costs by eliminating the number of units at the site during deployment.
Drilling Tubing Rolled
A relatively modern drilling technique involves the use of a circular pipe rather than a conventional drill pipe. This has the advantage of requiring less effort to enter and exit the well (the coil can only be run and pulled out while the drill pipe must be assembled and disassembled together by the joint when it stumbles in and out).
An additional advantage is that the tube is rolled through the hole through the stripper, mounted on the injector, which provides a hydraulic seal around the coil. It offers excellent outside control capabilities that is usually possible with drill pipes, and provides the ability to drill in balance.
Instead of rotating the drill bit by using a rotary table or top drive on the surface, it is rotated by a MUD MOTOR downhole, powered by the movement of drilling fluid pumped from the surface. Drilling supported by slurry motors rather than spinning pipes is commonly called shear drilling.
Usually sludge motors will be one component of the down hole assembly of Coiling Tubing Drilling. BHA also provides directional surveys, gamma, pressure, temperature, and in some cases, petrophysical logs during drilling. The latest generation of advanced drilling drilling tubing offers the ability to direct bits, allowing the well trajectory to be corrected in response to measurements made by the sensor.
Logging and perforating
These tasks by default are the cable fields. Because the tube is rolled stiff, it can be pushed into the well from the surface. This is the advantage of wireline, which depends on the weight of the chisel to be lowered into the well. For very distorted and horizontal wells, gravity may not be sufficient for logging with cables. Roller trunks and tractors can often overcome these losses by greatly reducing costs, especially on small platforms and underwater wells where rolled tubes will require the mobilization of costly mobile drilling rigs. The use of rolled tubes for these tasks is usually limited to the occasions where it is already on site for other purposes, eg logging runs after chemical washing.
Production
Coiled tubing is often used as a production string in shallow gas wells that produce water. The narrow internal diameter produces a much higher speed than would occur inside conventional tubes or inside the casing. This higher velocity helps lift the liquid to the surface, the fluid that may accumulate in the wellbore and eventually "kill" the well. Rolled tubing can be run inside the casing instead or in a conventional tube. When the rolled tube is run inside a conventional tube it is often referred to as a "speed rope" and the space between the outer part of the tube is rolled up and the inside of the conventional tubing is referred to as the "micro annulus". In some cases, the gas is generated into the micro-annulus. The umbilical tubular coiling can deliver submersible hydraulic pumps, electric submersible pumps and jet pumps into wells for permanent deliquification schemes and service applications.
Maps Coiled tubing
Rigging tubing lined
The main engine of circular tube intervention is the injector head. This component contains a mechanism to push and pull the coil in and out of the hole. The injector head has a curved guide beam on top called a gooseneck that threads the coils into the injector body. Under the injector is a stripper, which contains a rubber package of elements that provide a seal around the tubing to isolate well pressure.
Below the stripper is a deterrent, which provides the ability to cut tube tubes rolled up and close the wellbore (sliding-blind) and hold and seal around the pipe (pipe-slip). The old Quad-BOP has different ram for each of these functions (blind, shear, pipe, slip). The newer Dual-BOP combines several of these functions together requiring only two different sheep-blinds.
The BOP sits under the riser, which provides a pressurized tunnel to the top of the Christmas tree. Between the Christmas tree and riser is the last pressure barrier, BOP shear-seal, which can cut and seal the pipe.
Worldwide the number of tubular roll units has been increasing year by year in the last decade especially in the United States.
Onshore light rolled tubing unit
Coil tubing units (CTUs) are multi-purpose standalone machines that can do almost anything done by conventional service rigs - except for tripping jointed pipe. There are usually two types of superficial services - Arch and Picker. One uses a vertical lift with a horse's head above, and an injector hung with a tow rope from it. The Picker unit has a selector, and the horse bumps directly into the injector.
This type of coil tube unit has semi-permanent drums mounted in the middle of the vessel (They generally drive Class 3 trucks, 40 feet (12 m) long or more)
Coil Tubing Parts
Custom/generic tubular roller rollers, roller skates, curved rollers
See also
- Oil industry
- Oil & amp; gas drilling
References
External links
- Defining Coiled Tubing
- Intervention and Coiled Tubing Association
- Journal Tubing Tubing Times
- Live video feed from the BP tube roll operation in the Deepwater Horizon oil spill (visible in IE8)
- Introduction to Rolled Tubing: History, Applications, and Benefits//ICoTA, 2005
- Coiled Tubing: Industrial Conditions and Roles for NETL//US Department of Energy, National Energy Technology Laboratory, 2005
- COILED TUBING APPLICATIONS//SPE JPT, June 2007
- Manufacturing Process Tubing Tubing//Qualified Tubes, 2013
- Circular Tubing Community//Circular Tubing Community, 2015
- Rolled Tubing Equipment
Source of the article : Wikipedia
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