Salt precipitation during CO2 storage in deep saline aquifers can have severe consequences on injectivity during carbon storage. Extensive studies have been carried out on CO2 solubility with individual or mixed salt solutions; however, to the best of the authors’ knowledge, there is no substantial study to consider pressure decay rate as a function of CO2 solubility in brine, and the range of brine concentration for effective CO2 storage. This study presents an experimental core flooding of the Bentheimer sandstone sample under simulated reservoir conditions to examine the effect of four different types of brine at a various ranges of salt concentration (5 to 25 wt.%) on CO2 storage. Results indicate that porosity and permeability reduction, as well as salt precipitation, is higher in divalent brines. It is also found that, at 10 to 20 wt.% brine concentrations in both monovalent and divalent brines, a substantial volume of CO2 is sequestered, which indicates the optimum concentration ranges for storage purposes. Hence, the magnitude of CO2 injectivity impairment depends on both the concentration and type of salt species. The findings from this study are directly relevant to CO2 sequestration in deep saline aquifers as well as screening criteria for carbon storage with enhanced gas and oil recovery processes.

A laboratory investigation was carried out to experimentally determine the extent of the salt precipitation effects on the petrophysical properties of deep saline aquifer during CO2 storage. This was performed on selected core samples using laboratory core flooding process. The petrophysical properties (Porosity, Permeability) of the core sample were measured before core flooding using Helium Porosimetry and Scanning Electron Microscopy (SEM) to determine the morphology of the core samples. The core samples were saturated with brines of different salinities (5, 15, 25, wt% NaCl) and core flooding process was conducted at a simulated reservoir pressure of 1,000 psig, temperature of 45°C, with varying injection rates of 1.0, 1.5, 2.0, 2.5 and 3.0 ml/min respectively. The obtained results indicated that the porosity and permeability decreased drastically as salinities increases, noticeably because the higher concentration of brine resulted in higher amounts of salt precipitation. Porosity reduction ranged between 0.75% to 6% with increasing brine salinity while permeability impairment ranged from 10% to 70% of the original permeability. The SEM images of the core samples after the flooding showed that salt precipitation not only plugged the pore spaces of the core matrix but also showed significant precipitation around the rock grains thereby showing an aggregation of the salts. This clearly proved that the reduction in the capacity of the rock is associated with salt precipitation in the pore spaces as well as the pore throats. Higher injection rates induced higher salt precipitation which caused reduction in porosity and permeability. This is attributed to the fact that; the higher injection of CO2 vaporizes the formation brine more significantly and thereby increasing brine concentration by removing the water content and enhancing precipitation of salt. These findings provide meaningful understanding and evaluation of the extent of salt precipitation on CO2 injectivity in saline reservoirs. The insight gained could be useful in simulation models to design better injectivity scenarios and mitigation techniques

Conventional aerosols sprays contain different Volatile Organic Compounds (VOC). These organic compounds have different properties and can have detrimental impact on air quality. This study investigated the spray performance and variation of the types of Non-Methane VOCs (NMVOCs) expelled over the life of pressurised aerosol spray can. Three types of aerosol sprayshair sprays, deodorants, and antiperspirants were selected from the solventbased cosmetic products. Mass Ratio (MR) of solvent (ethanol) to propellant (LPG) for all the products was analysed at pressure decay sequences of 4, 3, 2, and 1.5 bar. It was found that the MR in hair sprays expelled was significantly higher than that of antiperspirants and body sprays by 53% and 54% respectively at 4 bar. As the pressure depleted, however, the antiperspirant and body sprays' MR decreased while that of the hair spray increased. At the lower pressures (2 bar), the hair spray had the highest MR and antiperspirant had the lowest. This finding is important in evaluating the performance of the delivery pathways of aerosol spray products and will provide insight into the effective design of atomisers with alternative "green" propellants like compressed air replacing LPG as the primary propellant in spray products.