DUOLINE GRE LINED TUBING VS CRA TUBING
| CRA TUBING | DUOLINE 20 LINED CARBON STEEL TUBING | |
| Tolerance to H2S | Selection of chrome levels in the tubing is based on H2S levels. Nickel alloys come into play when H2S levels are very high | Duoline liners have been extensively used in wells that dispose acid gases such as H2S upto 50% |
| Tolerance to CO2 | Most chrome tubing 13 Cr and above can handle CO2 very well but with limits on amount of chloride | Duoline liners are used in CO2 injection wells which pump in 100% CO2 down the hole |
| Tolerance to chlorides | Chrome tubing is sensitive to the levels of chlorides. The more the chlorides, the more is the tendency to undergo chloride pitting | Duoline liners perform better when the chlorides are high as the water is retained / held by the salt and not allowed to interact with the resin in the GRE |
| Tolerance to acids | Acid jobs are carried out through coiled tubing to prevent acid pickling of alloy steel | 28% HCl can be bull headed through Duoline lined tubing with no effect on the liner |
| Frictional losses | Surface smoothness is a key factor to reduce frictional losses. Metal surface is relatively rougher compared to composites; this results in higher pressure drop | Duoline is 6 times smoother than steel. So, even after the ID is reduced from lining the pipe, the flow rate maintains the same if not more compared with a unlined steel pipe |
| Galling during breakup | Chrome and CRA have higher inherent risk of handling and galling damage | Carbon steel with DUOLINE® installed has a much lower propensity for galling during running operations |
| Handling | Chrome and CRA have high inherent handling costs | Duoline lined carbon steel is handled through routine carbon steel handling procedures |
| Cost | CRA / chrome alloy tubing is prohibitively expensive | Duoline lined carbon steel comes at a fraction of the cost of CRA tubing |
| Delivery | Deliveries are over a year | Deliveries are up to a max of 6 months in most cases |
| Temperature | CRA can be applied up to much higher temperatures | Duoline temperature limit is 145 deg C |
| Intervention | CRA, being metal are more robust and can withstand intervention abuse to a greater extent | Recommended procedures have to be followed during interventions through Duoline |