A Code Comparison of Numerical Simulators for CO2 Geo-Sequestration
Engineering Honours Degree 2007
University of Adelaide
The primary objective of this report is to provide an assessment of the viability of using Roxar’s Tempest package to model geo-sequestration of carbon dioxide. The report provides a code comparison between his package and an Eclipse Compositional model incorporating the “GASWAT” keyword, which is specially designed for sequestration simulations. The code comparison was performed not only between the simulation outputs for each code but also between the well models and equations of state employed. A brief literature review is also provided which explores the key CO2 sequestration concepts mentioned in the report.
Through careful comparison of the well models it was found that despite their different syntax they were fundamentally the same. Likewise despite the equations of state being developed independently both made changes to existing equations in order to make them applicable for modeling CO2, in particular its interaction with brine.
In comparing the results of the code comparison between Tempest and E300 it was found that even though different equations of state were used and the fact that they were black-oil and compositional simulators respectively the outputs were very similar. In particular the predictions for the dissolution of CO2 in brine were remarkably alike over the 1000 year simulation period. Other parameters such as well bottom-hole pressure and free gas volume were also found to be very similar and although there were some slight disparities between the output saturation distributions these differences were not considered substantial by any means.
Following this analysis it was concluded that affirmation of Tempest as a viable and accurate CO2 geo sequestration simulator was suitable, and that its ease of use and compatibility with Eclipse suggest that it would be a beneficial package to be used in conjunction with Eclipse for comparative purposes.