A Matlab Based Tool Package for Interfacial Property Calculations

In the upstream operations of the oil & gas industry, the interfacial tension (IFT) of reservoir fluids greatly affects the efficiency of oil recovery process. Predicting the IFT of reservoir fluids is essential for the design of enhanced oil recovery (EOR) processes. To interpolate and extrapolate expensive experimental data, different theoretical and simulation methods have been developed to model the interfacial properties of reservoir mixtures. Among these methods, density gradient theory (DGT) has become a fast and accurate tool in the interfacial property prediction of many oil mixtures and water/oil mixtures.

In our work, the stabilized density gradient theory (SDGT) algorithm was developed to optimize the solving process of the DGT equations. We have also modified the DGT equations so that it can handle molecules with chain structures, such as surfactant molecules. By taking advantage of the SDGT algorithm and the modified DGT functions, we were able to conduct interfacial property calculations of oil mixtures, water/oil mixtures and water/oil/surfactant mixtures.

The Matlab based tool package was developed by integrating the prediction models we have developed into a user-friendly interface, which can be readily used by engineers to conduct fast and accurate reservoir property simulations. Some features of the package include phase equilibrium calculation, free energy analysis, IFT calculation and results plotting & exporting. The advanced numerical methods were implemented to speed up the calculation. The user-friendly interface and the user’s manual make it easy to use in practical calculations.