CFST will in general be used in wells requiring a metal CRA tubing completion. However, the corrosive film on the Titanium liner is much harder than metal CRA alloy. Therefore, it will be much more difficult to damage that film contrary to Duplex or Inconel alloys. However, it is recommended to design and execute interventions similar to high Chrome, Nickel, or Inconel tubing. Carbon steel intervention tools can chip off steel splinters which could be embedded in the metal CRA tubing and give access to corrosion. If it is necessary to perform Interventions, non-metallic centralizers should be deployed, reduced running speed, especially in dry completions, like gas-wells. Intervention tools shall be selected new, burrs filed off. Plastic coated wire is a distinct advantage in both types of CRA tubing.
Not all cutting tools are advisable. Obviously, chemical cutters will not work, similarly, they do not work on metallic CRA tubing. The electric pipe cutting tool from Sondex wireline has been successfully tested on these materials.
Yes, it can be milled but requires modified tools and reduced milling rates/conditions, bit type rpm, etc. The cuttings from milling the tubing are very light, and even lightweight, low viscosity brine will carry it to the surface.
In the case of severed tubing, the fishing operation is similar to metal tubing. The TOF can be dressed, fished internally, or externally. A grapple overshot with slips engaging on the outside of the tubing and possibly a spear inside could work equally well as with traditional metal tubing fishing.
In the unlikely event that after a bit and scraper run the well is not fully accessible, the impact of CFST tubing weighing one-third of its metal competitor is low. Furthermore, CFST is as strong as metal, no issues.
Yes, CFST tubing can be made-up to any standard, any manufacturer’s accessory, as well as to nipples for plugs, standing valves, beam-pump seating nipples, etc. Any conventional completion design can incorporate CFST tubing.
At the moment this has not been tested, however, looking at a large number of available alternative options, mechanical or explosive, it should be possible.
By their nature, non-metallic composites do not react to magnetic fields, very much like metal CRA tubing. CRA-Tubulars has an option to install depth correlation points for intervention in case there is a need for more accurate in-depth control. They are installed at the client’s request during the manufacturing of the tubing.
Yes, a hydraulic control-line can be incorporated into the outer layer. Using available SCSSV’s and packer with integrated control-line options, it can be supplied. Similarly, fiber optic cable can be integrated. Existing technology allows for the cable to exit the tubing, bypass the accessory, and connect to the optic cable below again.
Power cable for ESP can be “wrapped” in the out layer, providing a sturdy and protected alternative to traditionally banding to the outside of the tubing.
In conventional metal CRA completion, monitoring of corrosion during the production life of the well is desired.
Can we inspect, and is that needed, in non-metallic CRA tubing?
Pulsed Eddy is a technology that could be tried on this new development. It makes non-magnetic elements slightly magnetic showing wall thickness reduction. It is a proven technology in measuring riser wall thickness and airplane structure inspection.
Downhole Video is a visual option to investigate the condition of the inside of the tubing.
CRA tubulars intends to further develop this requirement for those clients needing to comply with this requirement.
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