Semi-submersible / drill ship riser analysis

We’ve extensive experience of performing floating rig drilling analysis globally, completing 35+ analysis projects in a range of water depths and environmental conditions.



The benefits of using riser analysis against semi-submersible and drill ships are vast, including the ability to reduce unnecessary costs, whilst providing valuable insight into the operations of using a floating vessel when subjected to global dynamic loads.

Common semi-submersible / drill ship analysis includes:

  • Operating envelope analysis to predict the limiting environmental conditions for the planned drilling campaign.
  • BOP tethering analysis to determine whether BOP tethering is required and to optimise the system design for each location
  • Wave fatigue analysis to determine the wellhead and conductor fatigue lifetimes from repeated wave loading
  • VIV fatigue assessment to compute VIV fatigue damage of the wellhead and conductor if onerous VIV lock-on was predicted from the VIV assessment.
  • Weak point analysis to determine the maximum limiting rig offset that the riser can stay connected without damaging the well or rig equipment. This can be compared with a broken mooring line analysis or incorporated into emergency disconnect procedures.
  • Capping stack analysis to ensure the well is structurally acceptable with a capping stack installed, as the additional subsea equipment can increase loads on the conductor.
  • Conductor axial load assessment to verify if the surrounding soil has sufficient capacity to support the well loads. Often the soil conditions are soft and the conductor needs to be suitable designed to avoid the well subsiding (sinking).
  • Conductor jetting analysis to calculate the axial capacity of the soil during jetting and provide recommendations for when further equipment can be installed on the conductor.
  • Riser hang-off analysis to determine if the hung-off riser is acceptable during storm conditions to mitigate against costly damage to riser joints.
  • Installation analysis to find the maximum allowable environmental conditions for installing the conductor, surface casing and riser to minimise potential rig downtime waiting on weather, providing significant cost savings to the drilling operations.
  • Cement optimisation analysis to determine the lowest acceptable cement top elevation. This can reduce risk to drilling operations and reduce costs by avoiding the need for costly equipment and rig time to remedy cement issues.
  • Soil sensitivity analysis to determine the influence of the soil properties on the results and conclusions. Gauging the impact of the soil profile has previously enabled operators to better understand their risk and reduce operational costs.


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