Treatment of CO2 in the oil & gas and process industry has become more focused over the last years. This concerns processing, transportation and storage. There is a safety aspect related to this that is not sufficiently covered by available technology and knowledge, i.e. the formation of solid CO2 and the potential consequences thereof. One of the challenges is that the thermo-dynamics for CO2 rich mixtures is not fully documented, and furthermore that there is no tool available for simulating the behavio r of CO2 rich mixtures in extreme situations. At normal conditions CO2 can exist as both gas and solid. The solid state of CO2 is connected to pressure drop and low temperatures and can typically be a problem in connection with depressurization and pipe flow. There are many aspects where this subject arises:* Blowdown of process equipment with high content of CO2. During the blowdown process there is a risk of forming solid CO2 which may reduce flow areas. * Accidental depressurization during injecti on of CO2. Blow-out of an injection well may lead to formation of solid CO2 and hydrate. * Long distance transport of CO2-rich hydrocarbon in pipelines. As the pressure drops, there is a risk for solid CO2 formation.The project is using the CFD system Brilliant as its technology platform. Brilliant is a general finite volume based CFD-system (Computational Fluid Dynamic) with integrated FEM abilities (Finite Element) for stress analysis. Brilliant is designed to fully support multi-physic applications. SolidCO2-Sim is an extension of the "Simulation of CO2 in flow and depressurisation"-project, a project run by Petrell AS, with Total and Statoil as sponsors and clients. Also participating in the project are Ass. Prof. Tore Haug Warberg/NTNU, Ceetron AS and Kalkulo AS, as sub-contractors. The project started 28 September 2010, and will run until end of September 2013.