TCT is composed of a corrosion-resistant liner made of Titanium ASTM Grade-2. The liner is then covered with several layers of Aerospace grade carbon fiber and high-grade epoxy resin. The Ti. liner gives corrosion resistance and prevents permeation of any hydrocarbons into the CF layer. The CF layer provides strength in the axial and radial direction.

TCT is economical from a lifecycle cost perspective. It outlasts any high alloy metallic tubing. Considering the cost of several workovers, new tubing, chemical treatment, and cashflow impact resulting from shut-in periods, the price is very competitive. TCT is more economical than 13Cr tubing and certainly a lot less expensive than Duplex or Inconel tubing. TCT is priced slightly above CR13 tubing but will last many times longer.

CRA-Tubulars plans to manufacture tubing in-country or certainly within the region. In this model we expect to deliver Range 3 TCT tubulars in under 2 months, This is much faster than traditional jointed metal CRA completions. Delivery times of Duplex or Inconel are typically over 18 months.

No, to achieve the highest possible temperature resistance we are using highly crosslinked thus brittle resins. Our combination of resin, fiber, and the liner however is not brittle. Microcracks may occur in the outer layer over time –  this is normal and does not affect its performance in any way.

Since TCT is as strong as metal, the behavior is expected to be similar. During such conditions steel tubing, drill pipe, and collars have been seen expelled from the well. That will likely happen with TCT too. Will it happen sooner? Not sure, but even if the event fully escalates 50% faster than with metal, the consequences will not be different, only instead of say an hour, it might happen in 30 minutes. Nothing to avert the consequence of such an event can be done in that time frame. Steel pipe, casing, and tubing have been sand-cut in minutes resulting from the extreme velocities of the two mediums together. Similar expectations for TCT.

There is no reason, when looking at other Industries, to believe non-metallic composite is less strong than metallic are. Airplanes are made of carbon fiber (CF), F1 cars are accident impact strengthened with CF. They are all much stronger than metal equivalent material. The unique and extreme forces in an uncontrolled well flow cannot be counteracted by metal or non-metallic composites, they will perform similarly.

In most of the corrosive well-operating environments, the expected life exceeds 20 to 30 years. Titanium is very durable, corrosion-resistant, and in other industries like seawater coolers in nuclear power plants and chemical industries, it is the metal of choice for high corrosion resistance.

Carbon fiber is strong and nearly inert to corrosion bar wet/temperature degradation over time. CRA-tubulars apply a safety factor to the operating envelope. The (initial) operating limits are the limits CF would have after degradation.

We use a propriety cross-over design from carbon-fiber composite to any metal CRA alloy matching any type of premium or non-premium thread required by the client.

TCT 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.

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 TCT tubing weighing one-third of its metal competitor is low. Furthermore, TCT is as strong as metal, no issues.

Yes, TCT 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 TCT 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.

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.

The thermal resistance of carbon fiber (through-thickness) =0.8W/m-K.

The TCT total thermal resistance per length (1 meter) R=0.0339K/W

Carbon fiber has a negative Coefficient of Thermal Expansion (CTE) and since it is so much stiffer than the surrounding epoxy, the combined effect is dominated by the CF. Therefore, the Temperature Coefficient is between 1/3 and 1/2 of that of metal tubing.

Titanium on its own is used for Helium storage vessels because of its extreme low-temperature capabilities. Carbon fiber on its own was used on the Space Shuttle liquid Oxygen and Hydrogen tanks. Both applications are low-temperature environments. The difference in the operating envelope in CCS wells and the aforementioned applications are the forces and stresses experienced in wells. However, Titanium shows an increase in tensile strength when cooled down (Source Kobe Steel).

Low Temperature Characteristics
Neither commercially pure titanium nor titanium alloys become brittle even at extremely low temperatures. In particular, commercially pure titanium and Ti-5AI-2.5Sn ELI can be used even at 4.2 K (-269°C)