An Investigation on the Sensitivity Analysis of the Parameters of Proposed Wax Precipitation Model

An accurate prediction of phase behavior strongly depends on reliable input data. Even though the quality of input data for compositional models has been greatly improved, tuning of model is still considered a useful method of improving the predicted results. The main aim of this study is to determine the most suitable parameter(s) for tuning the solid phase. The predicted wax appearance temperature (WAT) using the In-house model and two different models has been tuned to the reported values using different fluids. The In-house model uses regular solution theory to describe solid phase (wax) nonideality, the liquid and gas phases behavior are described by an equation of state. Also the validity of the tuned parameters of a mixture for other mixtures has been tested. Several parameters could be used in tuning the solid model. These parameters include, fusion temperature (Tf), heat of fusion (∆hf), solubility parameters (δS ) and binary interaction parameters (BIP). The sensitivity analysis on different parameters was performed. These tests were performed on three different models (Won, Pan & In-house model) using the parameters mentioned above, for the reported data. The results showed that the T f is the most sensitive parameter while δS shows the least sensitivity in matching the WAT. Even though using Δh f could provide the same results as tuning T f , but the required changes are much higher and sometimes not practical. Also using BIP as the tuning parameter, requires a fairly large coefficient that makes it unsuitable to be considered as the tuning parameter.

Keywords:

Sensitivity Analysis , WAT , Solubility parameter , T f , Δh f