Influence of Methane in CO2 Transport and Storage for CCS Technology

CO2 Capture and Storage (CCS) is a good strategy to mitigate levels of atmospheric greenhouse gases. The type and quantity of impurities influence the properties and behavior of the anthropogenic CO2, and so must be considered in the design and operation of CCS technology facilities. Their study is necessary for CO2, transport and storage, and to develop theoretical models for specific engineering applications to CCS technology. In this work we determined the influence of CH4, an important impurity of anthropogenic CO2, within different steps of CCS technology: transport, injection, and geological storage. For this, we obtained new pressure-density-temperature (P rho T) and vapor-liquid equilibrium (VLE) experimental data for six CO2 + CH4 mixtures at compositions which represent emissions from the main sources in the European Union and United States, The P and T ranges studied are within those estimated for CO2 pipelines and geological storage sites. From these data we evaluated the minimal pressures for transport, regarding the density and pipeline's capacity requirements, and values for the solubility parameter of the mixtures, a factor which governs the solubility of substances present in the reservoir before injection. We concluded that the presence of CH4 reduces the storage capacity and increases the buoyancy of the CO2 plume, which diminishes the efficiency of solubility and residual trapping of CO2, and reduces the injectivity into geological formations.