Validation of 1D flow model for high pressure offshore natural gas pipelines

• 1D compressible flow model validated by running simulations on offshore natural gas pipelines.
• GERG friction factor formula compared to traditional Colebrook–White.
• For high pressure pipelines GERG 2004 equation of state gives most accurate results compared to other equations of state.
• Steady heat transfer model over predicts the amplitude of temperature changes in the flow.

Transportation of natural gas through high pressure large diameter offshore pipelines is modeled by numerically solving the governing equations for one-dimensional compressible pipe flow using an implicit finite difference method. The pipelines considered have a diameter of 1 m and length of approximately 650 km. The influence of different physical parameters which enter into the model are investigated in detail. These include the friction factor, equation of state and heat transfer model. For high pressure pipelines it is shown that the selection of the equation of state can have a considerable effect on the simulated flow results, with the recently developed GERG 2004 being compared to the more traditional SRK, Peng–Robinson and BWRS equations of state. Also, including heat accumulation in the ground is important in order to model the correct temperature at the outlet of the pipeline. The flow model is validated by comparing computed results to measured values for an offshore natural gas pipeline.