Predicting the yield stress of oil-wax gels with long-chained n-alkanes

The low ambient temperature and strong convective heat transfer during wax deposition in subsea pipelines tend to form hard wax deposits that impede the passage of the pipe pig. In this paper, a reasonable model was developed to predict the yield stress of wax deposits by its solid wax content. The model was validated by experimental results and published data of wax deposits. In addition, the long-chained n-alkanes in wax deposits were experimentally found to cocrystallize near the WAT due to their logarithmic normal distribution of carbon numbers. Based on the assumption of a single pseudocomponent in the wax deposit, the model was further derived as a function of the temperature and the average carbon number. The model prediction results are in good agreement with the experiment results. The effect of the average carbon number on the yield stress evaluated by the model is consistent with previous studies.