Olga A. Sabodash

Technical Solutions of the Active Ice Protection of Offshore Structures for the Russian Arctic

The device for active protection against ice loads using pneumatic soft shells (PSS) on offshore production platforms has been studied. For technical modeling of devices the Solid Works CAD system was applied. The calculation results of model of the main components of the device by contact with the ice field in the Sea of Okhotsk ice conditions have been obtained. Finally, recommendations on the future effective application of the structures ice protective equipment have been worked out.Copyright

Local Ice Loads on the Sakhalin-II Project Structures: Probability Analysis and Comparison by Existing Design Codes

In the study the probabilistic modeling of local ice loads and pressures on wide structure has been carried out. Probabilistic analysis has traditionally been focused on distribution of their maximum values. The “Molikpaq” (PA-A) ice-class platform for “Sakhalin-II” project is considered as an example. The input parameters were modelled by Monte-Carlo method taking into account of full-scale data in the Piltun-Astokhskoe field during 1989÷2002 ice seasons. A comparative analysis of local ice loads and pressures on wide structure has been made on the basis of the Russian and international design codes, standards and recommendations. The obtained local pressure values were compared with public available data collected on the “Molikpaq” (PA-A) platform.Some preliminary results and discussions are presented. Recommendations on the local ice loads and pressures for engineering design of structures on the Sakhalin offshore have been done.Copyright

Numerical CFD-model of contact interactions between hummock and ice fields for estimation of ice loads on Sakhalin offshore GBS platforms

A two-fluid Eulerian-Eulerian model accounting for the contact interactions between obstruction and hummock, stopped before a structure, and ice floes has been developed. In this work the ice cover is considered to behave as a continuous stream of drifting ice surrounded by the water phase. The technique accounts for the «ice-to-ice» interactions. Consequently, a multiphase computational fluid dynamics (CFD) model is formulated and used for the numerical modeling of the process. The input ice data were obtained from the full-scale observations of the ice conditions in the Piltun-Astokhskoe deposit area during 1989÷2002. Some preliminary results and discussions are presented.Copyright

Probabilistic Modeling of Extreme Value Distributions of Ice Loads on “Molikpaq” Platform for Sakhalin-II Project

Characteristics of the drifting ice cover and the scenarios of the ice loads on offshore structures are the major parameters defining durability and reliability of the ice-resistant platforms on the Sakhalin offshore.The study is devoted to the problems of probabilistic and numerical modeling of the process of interaction between the ice cover and the ice-resistant concrete structures on the Sakhalin offshore zone. Geometry of the “Molikpaq” (PA-A) platform for Sakhalin-II Project is used as an example. The input statistical data were received on the basis of full-scale observations of the ice conditions in the Piltun-Astokhskoe deposit area during 1989–2002.The distribution of probability exceedance of ice loads for various ice scenarios on the “Molikpaq” (PA-A) platform was received. A probabilistic estimation of extreme values of ice loads was carried out, taking into account return period of ice conditions.Copyright

Numerical Prediction of the Cooling of Burnt Cable for the Prevention of Re-Ignition

Fires in the cable structures are a serious danger for the offshore facilities. Inflammations of the cables are mostly caused by cable overheating as a result of power loads in the net or by the shortcut circuits. Fire extinguishing comes, in the first place, to neutralization of the external flame on its surface. However, even when the external flame is prevented, the re-ignition of the cable’s insulation may happen in case its metal core has not been sufficiently cooled down to a safe temperature level. It is therefore important to clarify the dynamics of the core cooling under the influence of the flow of extinguishing agents in order to manage the temporal characteristics of the entire process. The current paper reports a numerical model of a hot cable cooling under the influence of external flow. The model resolves the temperature fields as in the cable as in the surrounding media in connection with the flow profiles of the cooling agent. Several cooling scenarios are considered for the problem: natural convection of the cooling gas around the cable, and forced heat utilization due to an induced gas-water flow directed towards the cable. The model is validated with the use of experimental data presenting a suitable agreement with empirics.Copyright