Duoline Flush System to provide increased through-bore

The Duoline® Flush System is an extension and natural progression to the hugely successful Duoline DL System, which has been utilised in thousands of onshore & offshore wells worldwide over the past 10 years. Using the same component material with an enhanced internal geometry, we are now able to offer an increased through bore while still maintaining all the benefits of the original Duoline DL Ring system.

Duoline is a GRE lining system which when installed into carbon steel casing and tubing, protects the base material from corrosion from CO2, H2S, O2, chlorides and water, all or some of which may be present in the well fluid/gas. Reservoir clean-up using HCL acid up to concentration of 28% can be accommodated to ensure good flowrates.

Duoline may be installed into threaded oil country tubular goods (OCTG), either new or used, within most connection options. The Duoline Flush System employs the patented FL-RingTM system that permits lining of shoulder – to – shoulder premium connections without affecting the connections geometry and performance. The system can be installed into a wide range of diameters and weight bores.

Duoline can accommodate interventions with both coil tubing and wireline and procedures are already available for this operation.

System benefits

  • Lined with coupling in place as per standard mill procedures.
  • Installed into Premium shoulder connections with standard couplings.
  • No modification to connections.
  • No reduction of connection performance.
  • Fully wireline tested using a variety of toolstrings.
  • Flare provides liner edge protection.
  • Increased through bore.
  • CBR with proven dovetail design.
  • Standard Duoline GRE Liner.

When making-up the Duoline Flush System to unlined well accessories such as DHSV, packer assemblies etc., we must all ways interface to a DTP-FL accessory box with can either be incorporated into the well accessory design or into a cross-over. This design stops any galvanic action between the carbon steel Duoline GRE lined joints and the unlined CRA accessory.


  • Oil Production – High Water Cut, CO2/H2S/O2 present ESP Wells.
  • Gas Production – Wet Gas, CO2/H2S present.
  • CO2/Gas Injection – Wet Gas.
  • WAG/SWAG – Aerated Water, Raw Sea Water.
  • Water Supply – High Chlorides, Aerated Water.
  • Water Injection – Oxygenated, Produced, Deaerated, Raw Sea Water.
  • Polymer Flood – ASP Wells.
  • Disposal – Chemicals, Dirty/Effluent/Waste Water, Open Drain Systems.

Adapted from a press release by David Bizley

Published on 15/10/2015

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