A novel apparatus for measuring gas solubility in aqueous solution under multiphase conditions by isobaric method

With the increasing energy shortage and global warming, the oil/gas development and CO₂ sequestration are moving toward the deep sea, and such a geological environment is conducive to gas hydrate formation. At present, for the gas solubility of a hydrate solution system, only Duan's simulation data are widely accepted, and a systematic experimental study is absent. The conventional measurement instruments for solubility of dissolved gas lack control of hydrate phase change, detailed regulation of temperature and pressure, and liquid-solid separation of sampling analysis. This paper describes the working principle, design, and use of a novel apparatus that can measure gas solubility in the solution system in the presence of hydrate. The application of constant pressure equipment avoids disturbing the phase equilibrium and dissolution equilibrium of the system in the sampling process. The apparatus is attractive for the continuous measurement of gas solubility and the guarantee of high accuracy. In addition, an isobaric method is proposed for gas solubility measurement, which promotes the measurement system to reach the target equilibrium state quickly and obtains highly regular data of gas solubility under environmental conditions. The experimental data obtained by this work are highly consistent with the Duan model, and the relative errors of measurements are within 2%. Gas solubility data from this apparatus will provide theoretical support for estimation of the marine CO₂ sequestration capacity and prevention of hydrate blockage in oil/gas transportation.