Atteris performed a risk assessment together with Woodside to identify the potential threats to umbilical integrity. Key risks identified were further scour at the umbilical span touch down, umbilical instability leading to over-bending of the umbilical at the J-tube exit, and risk of damage to the J-tube seal. The analysis concluded that for the as-surveyed span configuration the risk of damage to the umbilical at the J-tube exit was acceptable, however scour studies concluded that there was a risk of ongoing scour further exacerbating the risk.
Potential options to stabilise the situation were evaluated and scored, including use of gravel dumping, mattressing and frond mats, with the preferred method being frond mats due to the simplicity and low risk associated with installation.
