Due to the requirement of reducing CO2 emission to control climate change and the demand of utilizing CO2 for enhanced oil recovery, carbon capture, transportation, and storage becomes more and more important. Recent years, industry and academia pay more attention to this area. Modeling of CO2 transportation in pipelines is crucial in engineering design and operation of these pipelines. However, there are no standalone industrial standards for CO2 transportation modeling due to a lack of valid operational and experimental data.
This paper will review up-to-date CO2 pipeline design and modeling especially focusing on the Equation of State (EOS). The most economical means of CO2 transportation is to keep it in dense phase. This is a big challenge for traditional Equations of State such as the Peng-Robinson equation and the SRK equation because they are more suitable for the vapor-liquid equilibrium properties of hydrocarbon mixture systems. Pure CO2 properties can be accurately predicted by the Span-Wagner equation. But impurities in CO2 can change the properties dramatically. It has been reported that both Peng-Robinson and Span-Wagner equations have been used in the energy industry for CO2 pipeline simulation.
This paper will present the results using different Equations of State for CO2 simulation. Different commercial software packages have been tested. The results show there is about 5% difference in density and a 3% difference in viscosity. The Peng-Robinson equation with Peneloux volume correction is more conservative in pressure drop calculations.