Wax formation assessment of condensate in South Pars gas processing plant sea pipeline (a case study)

The wax deposition from the gas condensate in South Pars gas processing plant causes a number of severe problems. These problems include: (1) deposits form on the reboiler tubes of stabilizer column and tend to reduce its duty (2) forcing periodic shut-down and removal of deposits (3) interrupting normal processing operations. An understanding of deposition, nature and propensity is necessary to mitigate the mentioned problems. In this work, the multi solid phase model is used to predict the wax precipitation from gas condensate fluid. For five different reservoir fluids, several methods were investigated to split the heavy hydrocarbon fraction into pseudo fractions. The results show that the Al-Meshari method is the most accurate one. Also, a set of consistent correlations were used to calculate the critical points, fusion properties and the acentric factor of the single carbon number groups in the extended composition. Finally the best methods for predicting the wax formation are selected and used to predict the wax formation in the sea line of South Pars gas processing plant. The modeling shows that wax precipitation starts at 293 K and 86 bar. At this pressure and temperature the pipeline is 94 km away from the wellhead.

► Wax deposition in South Pars gas processing plant causes a number of severe problems.
► In South Pars refinery preventing the wax formation could prevent debris formation.
► In this work the best methods for predicting the wax formation are selected.
► Wax formation in sea line is predicted with selected methods.
► Wax precipitation starts at 293 K and 86 bar in the sea line (94 km far from wellhead).