(87c) Predicting the Properties of CO2-Natural Gas Mixtures for CCSS Projects

There is mounting evidence that rapid global warming is caused by CO2 emission into atmosphere.  There is a consensus among nations that CO2 emission to the atmosphere must be controlled via creating economically viable technologies for capturing, separation and long term storage of CO2 (CCSS). One of many possible proposed sequestrations is the injection of CO2 into depleted oil and gas fields.  However for planning such CO2 sequestration projects, accurate estimation of CO2-natural gas properties is required.

In this study a large data bank containing physical properties of various mixtures of CO2-natural gas properties at various temperatures and pressures has been collected. The data bank has been used to assess the accuracy of the industry standard methods as well as the recently published ones. The study indicated that these methods have series errors when they applied at high pressures, high temperatures, or at high content of CO2.

A new method is proposed in this study to calculate compressibility factor and density of CO2-natural gas mixtures.  It is capable of estimating the CO2- natural gas mixtures properties at various temperatures and pressures and for any level of CO2 content. The new method is useful for designing pipeline, compression and storage of CO2 in CCSS projects.