Blockage of pipelines due to hydrate formation is one of the challenging flow assurance problems encountered in offshore production systems, as it can reduce production, and can cause significant economic losses. To remove the hydrate plug, one-sided depressurization operations can be carried out. However, due to the large pressure differential, the plug can reach extremely high velocities, and pipeline rupturing may occur. Further, during the depressurization process, the temperature increases and the pipeline insulating material may deteriorate. To aid in the risk reduction of such operations, numerical simulations have become an attractive tool to predict the plug's behavior in different conditions. The present work presents a model to predict the displacement of plugs in transient two-phase flow conditions, coupled with a compositional model to determine gas condensate formation. A transient model to account for the energy stored in the insulating layers is included. This model prediction for a challenging one-sided depressurization scenario in a typical subsea flowline and riser case is compared with the traditional thermal resistance approach. Results showed that the large pressure differential leads to a sharp increase of the plug velocity, followed by a slow deceleration. Due to the fast transient inside the pipe, the energy stored in the insulating layer presents a great impact in the heat loss to the external environment, reducing the peaks in the flow temperature.