Measurement of CO_2 Saltwater Solution Density at states of Aquifer

Abstract

Geo-sequestration had been gradually considered to be one of the practical options to mitigate CO_2 concentration from the atmosphere. To estimate and understand the geophysical and geochemical dynamics of injected CO_2 and interactions with reservoir fluids and rocks, the physical properties of CO_2 solution, especially the density, are necessarily the basic data required. With focused on this, an experimental investigation was carried out to directly measure the density and density change of CO_2 saltwater solution. In this paper, the details of the experiments, including the measurement principle and method, and the last measurement results, are reported. It is found, at pressure range from 10.0 to 20.0MPa and temperature from 303.15 to 323.15K, that the density ratio of CO_2 solution to saltwater is increased nonlinearly with the increase of CO_2 mass fraction. The change rate in density due to change in dissolved CO_2 mass fraction appears to be independent on the pressure but sensitive to the temperature. This change rate decreases from 0.26 at temperature of 303.15K to 0.18 at 323.15K while the CO_2 mass fraction is 0.04.