Pigging Simulation for Rich Gas Transmission Pipelines

For rich gas transmission scheme, extraction of NGL from natural gas is not required in oilfiled or gas condensate field, so the gas treatment process in the field is simplified and the expense for the storage and transmission of NGL is saved.Rich gas can be transported in single phase at conventional pressure, in dense phase, or in two-phase.Herein, the technique for rich gas treatment is discussed and the technical characteristics of various rich gas transmission modes are compared.And a new simple pigging model is developed for predicting pigging operation in high pressure rich gas pipelines, with low-liquid loading, which is coupled the phase behavior model (adopting PR equation of state) with the hydrodynamic-thermo-dynamic model.The comparison of the calculating results with that of the two-phase transient computational code OLGA (with a dynamic, one-dimensional, extended two-fluid model) indicates that the pigging model has better precision and higher speed in calculation, and has the capability of pig-tracking and slug-length-increasing model and is suitable for engineering design.