Evaluation of Insulation Thickness Requirements during a Shut-Down Situation for Gas Hydrates Formation Prevention

Gas hydrate formation is a major flow assurance problem experience during production and transportation of gas/condensate and is almost impossible to eliminate but can be prevented. Hydrate formation can occur and affected by the changes in composition, pressure and temperature of the hydrocarbon fluid. It is vital to prevent the formation of hydrate because of the harm it causes to production facilities. This study evaluates the insulation thickness requirements during a shut-down situation for gas hydrates formation Prevention. Gas properties and PVT table files were created and modelled in multiflash and exported in a readable format to OLGA. A pipeline model was built and developed in OLGA with pipeline materials and geometry data inputted. Polyethylene foam insulation materials was selected with varying thickness of ۵mm, ۱۰mm, ۱۵mm, ۲۰mm and ۲۵mm after shutting down for twelve(۱۲) hours to evaluate the effect on hydrate formation during shut down situation. Results indicate that increase in insulation thickness increases the point of hydrate stability along the pipeline. Also, increase in the insulation thickness decreases the hydrate volume fraction and no hydrate was form for ۲۵mm insulation thickness. Hydrate formation in the pipeline can be avoided with the use of a high insulation thickness.

Keywords:

OLGA , Shut-down , Insulation Thickness , Hydrate volume fraction , Hydrate Stability