The problem

When Probe received an order for a coiled tubing stress joint, they found it was much more than just a standard manufacture solution that was required. The client, Helix Well Ops, were seeking design assistance/validation, manufacture and rigorous testing of the product in compliance with both their specific requirements and industry standards.

From playing a key role in the Macondo deep-water oil spill response, to end-of-life plug and abandonment work, Helix Well Ops is an established player in rigless offshore well intervention, providing fast, flexible and high-quality well management services. They enlisted the support of Probe to allow them to complete a well recovery project for a client.

Coiled tubing is a continuous reeled steel pipe which is used in well completion, workovers, drilling and production. The most important performance properties of coiled tubing are its rated values for axial tension, burst pressure and collapse pressure. The stresses are caused by internal and external pressures and the axial force that is either tension or compression. The required stress joint provides the transition between the flexibility of the subsurface release (SSR) connectors and the stiffness of the Christmas tree interface equipment.

The solution

Probe's pressure test bay

The original order was to manufacture, test and certify a coiled tubing stress joint. However, as the project progressed, the specification changed significantly. The stress joint was to be used in two different modes. This meant that a very thin section between the flanges and special clamp assemblies were required to increase the outside diameter of the centre sections when used in the secondary mode. Probe responded by manufacturing the clamp assemblies and also the flanged pulling heads. These would be used during the hydrostatic testing, which would be carried out by Probe prior to the product being shipped.

When manufacturing the stress joint itself, the material requirements meant that it was necessary to part machine the forging close to its finished size and then heat treat and test the steel using a prolongation. Once the mechanical testing had been carried out, the stress joint was machine finished to the client’s requirements.

In the final stage of the project, Probe were required to carry out a range of testing on the stress joint. This included proof tension and compression as well as hydrostatic pressure testing. To enable these procedures to be performed, Probe fabricated a large bespoke test frame, weighing approximately nine tonnes. Strain gauges were installed to verify the results of the calculations provided by a design engineer. Full non-destructive testing (NDT) including magnetic particle examination, ultrasonic examination and hardness testing was then carried out. This was all witnessed by Bureau Veritas (BV), a third party testing, inspection and certification company who worked in partnership with us to assess the required standards and measure against them as required.

The result

Helix Well Ops received a full turnkey solution from Probe. We responded innovatively when the requirements changed throughout the project, resulting in a manufactured and fully tested stress joint which has two modes of use. The product was supplied painted to the design specification requirements. This piece of equipment was essential for Helix Well Ops to deliver efficiently and on time to the end client.

We are delighted to have provided a complete in-house solution for this project. We are extremely proud of our testing capabilities and this project has fully utilised these facilities, especially as we were required to produce a bespoke test frame.



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