Carbon dioxide solubility in saline aqueous solution at various pressure and temperature
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Date
2015
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Publisher
Universiti Teknologi Malaysia
Abstract
Carbon dioxide (CO2) sequestration in aquifers is one of the highly anticipated methods by which concentration of CO2 in the atmosphere can be mitigated. Solubility of CO2 in brine is one of the contributing trapping mechanisms by which CO2 is sequestrated in aquifers. The aim of this study was to investigate the effects of various parameters such as pressure, temperature, salinity, brine composition, and purity of the stream on the solubility mechanism. Experiments were conducted at pressures up to 210 atm, temperatures from 298-373 K, and brine salinity ranging from 0 to 15,000 ppm. Solubility was found to have increased with increasing of pressure according to the temperature, salinity, and composition of brine. On the contrary, effects of salinity and temperature on the solubility were adverse. At 373 K, which was the highest temperature of experiments up to 12% reduction had been observed in the solubility of CO2 in water, as compared to that of ambient temperature. Increasing the salinity to values up to 15000 ppm caused the reduction in the solubility up to 20%. Effect of brine compositions (sodium chloride, magnesium chloride, calcium chloride and sodium bicarbonate) on the solubility was also discussed using salting-out effect concept. Nitrogen and argon were also added to the CO2 stream as impurities at various concentrations. Effects of those impurities at low concentration were found to be negligible, however, at higher concentrations substantial drop in the solubility was observed. In addition to that, experiments were conducted to investigate the solubility of CO2 in conditions representative of Malay Basin. Empirical models were also developed based on the experimental data and verified by the previous models and experimental data. The effects of solubility of brine on changes of density of formation brine was also discussed. The outcomes of this research can enhance the understanding about solubility of CO2 in aquifers, which could eventually facilitate in large scale implementation of CO2 sequestration as a method to mitigate concentration of CO2 in atmosphere and alleviate the global warming.
Description
Thesis (PhD. (Petroleum Engineering)
Keywords
Aquifers—Malaysia, Geological carbon sequestration—Malaysia, Carbon sequestration—Research