Evaluation of Scale Calculation Programs – Phase 1: Comparison of programs on the basis of synthetic, binary and ternary brine systems
In order to evaluate the performance of scale calculation programs, five such programs were used for calculating a number of test systems. The test systems were binary and ternary data sets published in international scientific journals. For each of the data set it was known that the brine was in equilibrium with a scale mineral. The test systems consisted of fourteen data sets concerning sulfate scaling minerals and six data sets concerning carbonate scaling minerals. The test systems were chosen so that they covered as broad pressure, temperature, and concentration ranges as possible. The data sets also cover a wide range of pH due to the different amounts of carbonate and dissolved carbon dioxide.
The scale calculation programs chosen for the comparison were FROCKI from DGMK, Scale-Chem from OLI, MultiScale from Petrochem, DownholeSat from French Creek Software, and Extended UNIQUAC from IVC-SEP, Technical University of Denmark.
The results of the comparison project were reported in a number of figures showing phase diagrams, parity plots, and graphs for saturation indices. A grading system was used to describe the performance of each model for each test system. An overview of the ratings obtained by the scale calculation programs is given in tables.
It was found that none of these scale calculation programs was able to satisfactorily describe the limit for scale formation in all of these model systems. The three programs that performed best were Scale-Chem from OLI, Extended UNIQUAC from Technical University of Denmark, and MultiScale from Petrochem.