| dc.description.abstract | Two different templates, template A and template B, for subsea oil and gas production are studied in this work. Numerical time-domain simulations for the crossing of the splash zone are run in OrcaFlex. Template A has suction anchors that have a diameter of 6 m and a height of 7.9 m, while template B’s suction anchors have a diameter of 5.5 m and a height of 8.225 m. This thesis presents the numerical model and setup of the system, as well as the results of the simulations. The significant wave height was set to 2 m, the wave direction to 165 degrees and the following mean zero up-crossing periods: 4 s, 6 s, 8 s and 10 s. The results showed that the Gumbel probability paper for template A, with a mean zero up-crossing periods of 4 s, did not satisfy the 95 % probability of non-exceedance. It was also noted that the dynamic response decreased with increasing mean zero up-crossing periods.
Additionally, a HAZOP study is performed for the lifting operation. The hazards for the four phases lift-off and in-air manoeuvring, splash-zone crossing, deeply submerged, and landing, are identified and assessed. It was found that excessive tension, loads and motion were causing the majority of the hazards in the lift-off- and in-air-manoeuvring phase and the splash-zone-crossing phase. Therefore, the two first phases of a marine lifting operation depend significantly on the weather conditions. The deeply-submerged phase and the landing phase involve a high number of potential threats. Misalignment with the production system is a detrimental consequence. The operation must be carefully planned and coordinated. | |
