Sustainable Marine Structures

Dynamic Analysis of Splash-zone Crossing Operation for a Subsea Template

Adham M. Amer

Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, Norway

Lin Li

Department of Mechanical and Structural Engineering and Materials Science, University of Stavanger, Norway

Xinying Zhu

Havfram AS, Stavanger, Norway

DOI: https://doi.org/10.36956/sms.v4i2.596

---

Abstract

Subsea templates are steel structures used to support subsea well components. Normally, offshore crane vessels are employed to install them to the target location on the seabed. Crossing the splash-zone during the lowering of a subsea template is considered the most critical phase during the installation due to slamming loads and needs to be studied to provide the operational weather criterion during the planning phase. In this study, dynamic response analysis has been carried out to evaluate the allowable sea states for the plash-zone crossing phase of the subsea templates. The numerical model of the lifting system, including the crane vessel and the subsea template, is firstly built in the state-of-the-art numerical program SIMA-SIMO. Then, dynamic analysis with time-domain simulations is carried out for the lifting system under various sea states. The disturbed wave field due to the shielding effects from the installation vessel is considered when calculating the hydrodynamic forces on the template. Statistical modelling of the dynamic responses from different wave realizations is used to estimate the extreme responses of various sea states. The application of the generalized extreme value distribution and Gumbel distribution in fitting the extreme responses is discussed. Moreover, the influence of the shielding effects from the vessel, as well as the influence of the changing size of the suction anchor on the hydrodynamic responses and the allowable sea states are studied. 

Keywords: Splash-zone crossing; Subsea template installation; Shielding effect; Allowable sea states

---

References

[1] Li, Y., Zhao, H., Xu, N., et al., 2020. Study of the Installation Process of the Subsea Tree Passed Through the Splash Zone. Energies. 13(5), 1014.

[2] Jia, D., Agrawal, M., 2014. Fluid-structure interaction: lowering subsea structure/equipment in splash zone during installation. Offshore Technology Conference. Offshore Technology Conference.

[3] Wang, Y.Y., Tuo, H.H., Li, L.W., et al., 2018. Dynamic simulation of installation of the subsea cluster manifold by drilling pipe in deep water based on OrcaFlex. Journal of Petroleum Science and Engineering. 163, 67-78.

[4] Jacobsen, T., Naess, T.B., 2014. Installation of subsea structures using mid-size construction vessels in harsh environments. Offshore Technology Conference-Asia. Offshore Technology Conference.

[5] Gordon, R.B., Grytøyr, G., Dhaigude, M., 2013. Modeling suction pile lowering through the splash zone. ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers Digital Collection.

[6] Li, L., Parra, C., Zhu, X., et al., 2020. Splash zone lowering analysis of a large subsea spool piece. Marine Structures. 70, 102664.

[7] Li, L., Gao, Z., Moan, T., 2016. Operability analysis of monopile lowering operation using different numerical approaches. ISOPE.

[8] DNV·GL, 2017. Recommended practice: Modelling and analysis of marine operations, DNVGLRP-N103.

[9] DNV·GL, 2017. Recommended practice: Lifting appliances used in subsea operations, DNVGLRP-N201.

[10] Acero, W.G., Li, L., Gao, Z., et al., 2016. Methodology for assessment of the operational limits and operability of marine operations. Ocean Engineering. 125, 308-327.

[11] Li, L., Gao, Z., Moan, T., 2015. Response Analysis of a Nonstationary Lowering Operation for an Offshore Wind Turbine Monopile Substructure. Journal of Offshore Mechanics and Arctic Engineering. 137(5).

[12] Bai, Y., Bai, Q., 2010. Subsea engineering handbook. Elsevier: Amsterdam; Boston; Paris.

[13] Bunnik, T., Buchner, B., 2004. Numerical prediction of wave loads on subsea structures in the splash zone. in The Fourteenth International Offshore and Polar Engineering Conference. International Society of Offshore and Polar Engineers.

[14] Damblans, G., Berhault, C., Marcer, R., et al., 2012. CFD and Experimental Investigations of Slamming Load Prediction on Subsea Structures in Splash Zone. The Twenty-second International Offshore and Polar Engineering Conference. OnePetro.

[15] Buchner, B., Bunnik, T., Honig, D., et al., 2003. A new simulation method for the installation of subsea structures from the splash zone to the ultra deep. DOT conference

[16] Ren, B., Wang, Y., 2004. Numerical simulation of random wave slamming on structures in the splash zone. Ocean Engineering. 31(5-6), 547-560.

[17] DNV·GL, 2014. Loadout, transport and installation of subsea objects, DNVGL-OS-H206.

[18] Li, L., Amer, A.M., Zhu, X., 2020. Numerical analysis of an over-boarding operation for a subsea template. Journal of Ocean Engineering and Science.

[19] Ocean, S., 2018. SINTEF Ocean, SIMO 4.12.1 Theory Manual.

[20] DNV·GL, 2018. Enviromental conditions and enviromental loads, DNVGL-RP-C205.

[21] Solaas, F., Sandvik, P.C., 2017. Hydrodynamic coefficients for suction anchors during installation operations. in ASME 2017 36th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers Digital Collection.

[22] Li, L., Gao, Z., Moan, T., 2015. Comparative study of lifting operations of offshore wind turbine monopile and jacket substructures considering vessel shielding effects. The Twenty-fifth International Ocean and Polar Engineering Conference. OnePetro.

[23] Li, L., Zhen, G., Moan, T., et al., 2014. Analysis of lifting operation of a monopile for an offshore wind turbine considering vessel shielding effects. Marine Structures. 39, 287-314.

[24] Næss, T., Havn, J., Solaas, F., 2014. On the importance of slamming during installation of structures with large suction anchors. Ocean Engineering. 89, 99-112.

[25] DNV·GL, 2016. Standard: Marine operations and marine warranty, DNVGL-ST-N001.

[26] Baarholm, G.S., Haver, S., Økland, O.D., 2010. Combining contours of significant wave height and peak period with platform response distributions for predicting design response. Marine Structures. 23(2), 147-163.

[27] Solaas, F., Sandvik, P.C., Pâkozdi, C., et al., 2017. Dynamic forces and limiting sea states for installation of grp protection covers. International Conference on Offshore Mechanics and Arctic Engineering. American Society of Mechanical Engineers.