Vessel Icing on the Shtokman FPSO
Authors: Efimov Yaroslav , Kornishin Konstantin 
Published: December 2012

Abstract
The main objective of the paper is to create and develop a theoretical modelof spray icing on sea vessels and floating oil and gasexploration&production structures and facilities. The main goodness of fitis particular match of the model's results with vessel records and observationsdata published in special literature. Besides factors affecting the vesselicing are discussed and methodology of their quantitative accounting isproposed. In the paper authors used study materials from different courses, which were taken by them in the University Centre in Svalbard, University inStavanger and Gubkin Russian State University of Oil and Gas. We would alsolike to mention that authors prepared the work in close collaboration, overwhelming majority of issues was discussed and the whole paper represents aresult of a joint work and therefore most of the arguable points werehighlighted and scrutinized. The work presents mostly analytical approaches butfor some integrals calculations special numeric simulation software Maple™ wasused. This paper is the first part of Cold Climate Operations research and nextpart will be dedicated to the winterization challenges.

Introduction
Vessel icing is known to be a serious threat for the vessel stability andpossibility of carrying out marine operations in cold regions of high latitude(See Fig. 1). Ice accumulation can easily cause vessel destabilization andcapsizing - and there are lot of records of such accidents from the veryancient times up to the last year. On of possible reasons the Kolskaya jack-upcapsized as it is discussed now was icing on the platform together with harshenvironment conditions.
With regard to the latest news from Gazprom and Shtokman Development A.G.there is a need to reconsider the development concept for the Shtokman field toimprove insufficient economy of the project. This anticipates possibility offull subsea production with no floating facilities which has shown goodperformance on the Ormen Lange, Norway. For the effect of different conceptestimations winterization concerns are also important and may put certainlimitations on the possible technical solutions.
Despite of the fact that the phenomenon of vessel icing has a long recordhistory it is not well studied and even discussed. The answer to this is thefact that first knowledge of vessel icing was presented by fishermen and marineexplorers. And it is quite obvious that they didn't stay in the area where thevessel was subjected to icing - on the contrary the only rational action toescape was to leave to another location. Nowadays when world-growing demand ofhydrocarbons calls for exploration and production in severe Arctic region, theproblem of vessel icing has gotten new light. Point here is that duringexploration and all the more so production operations we merely can't leave thelocation for a very long time (depends on type of activity, for some of themtime of planned work is up to 50 years). It means that new methods of icingprevention and de-icing should be invented which is completely impossiblewithout clear understanding of mechanisms of the process.