ABSTRACT:

In the frame of deepwater and/or marginal field development, the selection of insulation system is one of the critical activities, being the pipeline thermal performances a possible bottleneck for field production and operations. Often, cost constraints as well as construction or installation limitations, more than operative suitability might force the choice of a specific system, since the operative envelope and steady state and transient thermal performances of an insulation system are not always available from vendors. In particular, evaluation of insulation requirements vs. flowrate and GOR, as well as cooldown duration vs. burial depth are key parameters in selecting a suitable insulation system both for nominal production conditions and to allow required operative procedures. The scope of the presented work is to identify and describe in details the available insulation systems and their characteristics, as well as to identify the appropriate methods to evaluate their efficiency both during steady production and during transient conditions (shutdown/restart). The efficiency of the considered insulation system is related to the capability to avoid the produced fluid to fall into solid formation zone (hydrate or wax). The proposed analysis will be performed by the following steps: State of art of pipeline insulation, including both active and passive systems, and evaluation of their overall performances; Definition of flow assurance constraint to evaluate the insulation effectiveness; Identification of the suitable models to design each of selected insulation systems; Finally, an example of implementation of different insulation systems and their effectiveness in solving flow assurance problems is reported

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