Individual Steam Assisted Gravity Drainage (SAGD) wellheads experience thermally induced growth on the order of 0.5 m to 1 m and create a bending moment or side loading due to thermal expansion. This wellhead thermal growth is large enough that ball joints are usually located in the piping system adjacent to the wellhead to accommodate the required growth and reduce the stress on wellhead connections and improve long term performance.

Typical design practice is to use two uniaxial swivel joints and one multiaxial flexible joint arranged at the bottom and middle points of the A-frame respectively. This design approach requires an alignment between the wellhead and adjacent piping that sometimes can't be achieved in the field.

The new A-frame design includes just one uniaxial swivel joint arranged at one bottom end of the A-frame (piping side) and two multiaxial flexible joints arranged at the other points of the A-frame. This configuration allows for the full 3-degrees of freedom needed to accommodate vertical and horizontal misalignment between the wellhead and adjacent piping. However, the stability of new A-frame design with different nominal pipe sizes under sustained load cases need to be evaluated by pipe stress analysis. The results of analysis revealed that the new A-frame design will be stable under sustained load cases without any risk of sagging in the field. Moreover, the new A-frame design has already started to be implemented within the industry and is validated under realistic field condition.

The novelty of the new A-frame design is in the ability to handle vertical and horizontal misalignment issues between the wellhead and adjacent piping during installation, reduce the installation times, increase the reliability of operation and reduce the nozzle loads at the wellhead side.

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