Atteris have recently completed a program of physical model testing for articulated concrete block mattresses in the Large O-Tube at the University of Western Australia’s Coastal and Offshore Engineering Laboratory (COEL). The testing was driven by the desire of one of Atteris’ clients to reduce the number of concrete block mattresses required to stabilise flowlines and umbilicals on a new single well tie-back. While articulated concrete block mattresses are regularly used to enhance stability of flowlines and umbilicals, the commonly employed design approach is highly theoretical and not well supported by physical model testing, leading to potentially over-conservative designs.
The test results provided an improved understanding of mattress failure modes, and in particular the concrete block mattress’ capacity to resist the loads applied by a flowline (or umbilical) when both are subjected to hydrodynamic loading. Atteris will use the test results to deliver significant cost savings in the stability design for the project in the next few weeks.
Atteris thanks University of Western Australia’s COEL staff for their great support during the testing program.