Subsea exploration well systems are subjected to complex loading due to vessel motion and hydrodynamic forces on the riser. Extreme loading and the fatigue design under operational loading are heavily dependent on the soil support along the uppermost section of the conductor casing.
Since 2017, 4Subsea, a leading provider of digital technology and services to the energy and maritime sector, has monitored BOPs and riser responses across several exploration drilling campaigns in the North Sea and the Barents Sea for Lundin Norway. The purpose is to track the performance of the wells over time, based on integrity parameters such as well stiffness, BOP resonance frequency and BOP motion rotational depth.
In one exploration well, the operator experienced escalating instability while drilling caused by washout, resulting from vessel and wave-induced motions on the BOP and by challenging soil conditions. An ROV was used to visually observe the movements of the BOP.