Caracterização termodinâmica de misturas ricas em dióxido de carbono

Abstract

The process of injection and reinjection of supercritical carbon dioxide is of great interest for the oil and gas industry as well as for CCS (Carbon Capture and Storage) applications, particularly in pré-salt wells. For this process to be designed and executed efficiently, it is necessary to know some thermodynamic properties of state and transport for the fluids applied. In this work, an experimental methodology for collecting equilibrium points and calibrating an equation of state (Cubic Plus Association – CPA) will be presented, as well as a thermodynamic methodology that uses CPA associated with departure functions to predict the main state and transport properties for CO2-rich mixtures. In addition to carbon dioxide, the mixtures will contain at least one of the following components: water, nitrogen, methane, propane and hexane, among others. The properties will be evaluated within the thermodynamic conditions consistent with the application presented above (approximately between 100 and 700 bar, and between 280 and 500 K). The results were compared with experimental data and values from commercial packages, in both cases it was observed that the proposed methodology presented satisfactory results, with average deviations inferior to 10% for most of the properties, and in all cases capturing the physical behavior of each property evaluated.