Radzuan Junin

TiO2 nanoparticle transport and retention through saturated limestone porous media under various ionic strength conditions

The impact of ionic strength (from 0.003 to 500mM) and salt type (NaCl vs MgCl2) on transport and retention of titanium dioxide (TiO2) nanoparticles (NPs) in saturated limestone porous media was systematically studied. Vertical columns were packed with limestone grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolent-visible spectrometry. Presence of NaCl and MgCl2 in the suspensions were found to have a significant influence on the electrokinetic properties of the NP aggregates and limestone grains. In NaCl and MgCl2 solutions, the deposition rates of the TiO2-NP aggregates were enhanced with the increase in ionic strength, a trend consistent with traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. Furthermore, the NP aggregates retention increased in the porous media with ionic strength. The presence of salts also caused a considerable delay in the NPs breakthrough time. MgCl2 as compared to NaCl was found to be more effective agent for the deposition and retention of TiO2-NPs. The experimental results followed closely the general trends predicted by the filtration and DLVO calculations. Overall, it was found that TiO2-NP mobility in the limestone porous media depends on ionic strength and salt type.

Transport and retention of engineered Al2O3, TiO2, and SiO2 nanoparticles through various sedimentary rocks.

Engineered aluminum oxide (Al2O3), titanium dioxide (TiO2), and silicon dioxide (SiO2) nanoparticles (NPs) are utilized in a broad range of applications; causing noticeable quantities of these materials to be released into the environment. Issues of how and where these particles are distributed into the subsurface aquatic environment remain as major challenges for those in environmental engineering. In this study, transport and retention of Al2O3, TiO2, and SiO2 NPs through various saturated porous media were investigated. Vertical columns were packed with quartz-sand, limestone, and dolomite grains. The NPs were introduced as a pulse suspended in aqueous solutions and breakthrough curves in the column outlet were generated using an ultraviolet-visible spectrophotometer. It was found that Al2O3 and TiO2 NPs are easily transported through limestone and dolomite porous media whereas NPs recoveries were achieved two times higher than those found in the quartz-sand. The highest and lowest SiO2-NPs recoveries were also achieved from the quartz-sand and limestone columns, respectively. The experimental results closely replicated the general trends predicted by the filtration and DLVO calculations. Overall, NPs mobility through a porous medium was found to be strongly dependent on NP surface charge, NP suspension stability against deposition, and porous medium surface charge and roughness.

Effects of sonication radiation on oil recovery by ultrasonic waves stimulated water-flooding

Due to partial understanding of mechanisms involved in application of ultrasonic waves as enhanced oil recovery method, series of straight (normal), and ultrasonic stimulated water-flooding experiments were conducted on a long unconsolidated sand pack using ultrasonic transducers. Kerosene, vaseline, and SAE-10 (engine oil) were used as non-wet phase in the system. In addition, a series of fluid flow and temperature rise experiments were conducted using ultrasonic bath in order to enhance the understanding about contributing mechanisms. 3-16% increase in the recovery of water-flooding was observed. Emulsification, viscosity reduction, and cavitation were identified as contributing mechanisms. The findings of this study are expected to increase the insight to involving mechanisms which lead to improving the recovery of oil as a result of application of ultrasound waves.

A role of ultrasonic frequency and power on oil mobilization in underground petroleum reservoirs

In oil industry, the reduction of oil production is of major concern as world’s necessity for oil increases. Therefore, developing and applying new techniques to mobilize residual oil left in the reservoir is important. Ultrasound technique is one of the unconventional methods to increase the productivity of oil wells, but in spite of many laboratory experiments on oil mobilization under ultrasound in porous media the precise mechanisms are weakly understood. Therefore, it is vital to perform basic experiments to achieve a good knowledge and deep insight into the mechanisms. To recognize the reason why ultrasound is able to mobilize residual oil left in pores, one must remember why oil droplet is trapped. Residual oil is left in pores because of insisting capillary forces. So, in this paper a mechanism related to capillary forces are developed to clarify the effect of ultrasound on mobilization of residual oil in porous media. In addition, some experiments are conducted with a 2D glass micro-model in which the mobilization of oil is observed using a digital microscope and camera. It was concluded from the result of experiments that the oil mobilization was proportional to ultrasound power and frequency.

Calcite precipitation from by-product red gypsum in aqueous carbonation process

The carbon dioxide (CO2) concentration of the atmosphere has been increasing rapidly, and this rapid change has led to promotion of CO2 reduction methods. Of all the available methods, CO2 mineral carbonation provides a leakage-free option to produce environmentally benign and stable solid carbonates via a chemical conversion to a more thermodynamically stable state. In this research, the precipitation of calcite from by-product red gypsum was evaluated for mineral CO2 sequestration. For this purpose, the impact of changing variables such as reaction temperature, particle size, stirring rate, and liquid to solid ratio were studied. The results showed that optimization of these variables converts the maximum Ca (98.8%) during the carbonation process. Moreover, the results confirmed that red gypsum has a considerable potential to form calcium carbonate (CaCO3) during the CO2 mineral carbonation process. Furthermore, the low cost and small amount of energy required in the use of by-product red gypsum were considered to be important advantages of the CO2 sequestration process. Therefore, the acceptable cost and energy required in mineral carbonation processing of red gypsum confirms that using this raw material represents a method for mineral carbonation with minimal environmental impact.

The Effect of Ultrasonic Waves on Oil Viscosity

This study presents the development of a technique to directly investigate the effect of ultrasonic waves at 25 and 68 kHz and 100, 250, and 500 W on the viscosity of paraffin, synthetic oil, and kerosene. Experiments were performed under both controlled and uncontrolled temperature conditions in a smooth capillary tube. The results indicate that the viscosity of the liquids decreases upon exposure to ultrasound and may be attributed to induced heat generation and cavitation within the fluid. The specifics of ultrasound frequency, power, and temperature on viscosity reduction are discussed and interpreted.

Experimental Investigation and Simplistic Geochemical Modeling of CO2 Mineral Carbonation Using the Mount Tawai Peridotite

In this work, the potential of CO2 mineral carbonation of brucite (Mg(OH)2) derived from the Mount Tawai peridotite (forsterite based (Mg)2SiO4) to produce thermodynamically stable magnesium carbonate (MgCO3) was evaluated. The effect of three main factors (reaction temperature, particle size, and water vapor) were investigated in a sequence of experiments consisting of aqueous acid leaching, evaporation to dryness of the slurry mass, and then gas-solid carbonation under pressurized CO2. The maximum amount of Mg converted to MgCO3 is ~99%, which occurred at temperatures between 150 and 175 °C. It was also found that the reduction of particle size range from >200 to <75 µm enhanced the leaching rate significantly. In addition, the results showed the essential role of water vapor in promoting effective carbonation. By increasing water vapor concentration from 5 to 10 vol %, the mineral carbonation rate increased by 30%. This work has also numerically modeled the process by which CO2 gas may be sequestered, by reaction with forsterite in the presence of moisture. In both experimental analysis and geochemical modeling, the results showed that the reaction is favored and of high yield; going almost to completion (within about one year) with the bulk of the carbon partitioning into magnesite and that very little remains in solution.

Natural polymer flow behaviour in porous media for enhanced oil recovery applications: a review

Abstract When a reservoir is flooded with polymer, the mobility ratio between the displaced fluid and the displacing fluid become favourable compared to the conventional water flooding. In the oil and gas industry, the synthetic polymer polyacrylamide in hydrolysed form and the biopolymer xanthan are being used for this purpose. However, the polyacrylamide is susceptible to high temperature and salinity. Also, its synthetic nature makes it harmful to the environment. The biopolymer xanthan has the problem of degradation and both are very expensive. With the shortfall in crude oil price and the high cost of exploitation and drilling new wells, there is need to look inward and think out of the box in formulating new improved polymers that can combat these problems. Natural polymers from agricultural and forest produce are abundant in nature, cheap and environmentally friendly. These agricultural and forest produce contain starch and cellulose which are known to have rigid and long polysaccharide chains that can withstand the harsh reservoir conditions. But the design of a polymer flood or a permeability-modified process involving polymer requires knowledge about the polymer flow mechanism and the rheological behaviour of the porous media. This paper, therefore, reviews the available natural polymers that can be used for enhanced oil recovery applications and the mechanism affecting their flow behaviour in porous media. The emphasis is on the physical aspect of the flow, the microscopic rheological behaviour of the natural polymers. The dominant mechanism of the flow process was adsorption, mechanical entrapment and hydrodynamic retention. It was observed that the polymer exhibited non-Newtonian, pseudoplastic and shear-thinning behaviours. The literature review on oil displacement test indicates that natural polymers can recover additional oil from an oil field. Environmental application issues associated with the application of natural polymers have opened new frontier for research and are also highlighted herein.

The effects of polymer and surfactant on polymer enhanced foam stability

Polymer addition to foam has been proposed to enhance foam stability. Polymers can be used as a viscosifying agent of the aqueous surfactant solution of the external phase of foam, increasing apparent foam viscosity and thus reducing foam drainage rate. In this study a high and low molecular weight of partially hydrolyzed polyacrylamide polymer were used as the viscosification agent. Two ionic surfactants including Sodium dodecyl benzene sulfonate (SDBS) and Sodium dodecyl sulfate (SDS) were also used as the foaming agent. All solutions were also prepared in fresh water and 2-wt% NaCl to emphasize the effects of salt presence on foam stability. Experimental results showed that both SDS and SDBS surfactants were compatible with polyacrylamide polymer addition and promising results were achieved. Higher molecular weight polymer was more effective than lower molecular weight and produced foams were more stable when high molecular weight polymer was used. Foam stability was in a direct relationship with polymer addition and increasing polymer concentration enhanced foam stability in all solutions.

The evaluation of borehole imaging result comparing with cores in Sarvak fractured and non-fractured reservoir

Core samples are still today considered as the standard measurement against all other measurements which must be compared. Core analysis usually focuses on the worse portion of the reservoir due to the fact that core recovery has rarely been well in a highly fractured zone; hence, permeability measured from core sample is often not representative. Core analysis is a common method to identify small-scale fractures of the well and permeability and porosity; however, there are some limitations in the core procedure such as it is highly expensive and unidirectional and has a low recovery coefficient in fractured zone. In contrast, there tends to be a mistrust and even a suspicion of those logging instruments that make measurements which threaten to replicate or even replace the “sacred core.” Thus, image logs are more useful to study the subsurface fractures in these such cases and the logs which come closest to achieving this are the high-resolution micro resistivity (OBMI) and acoustic geological imaging (UBI). The core and OBMI-UBI result was matched in order to verify the log measurements. Furthermore, FMI data were integrated with other open-hole logs to derive a permeability curve. As demonstrated in the case studies, it is believed that the permeability in the basement could be reasonably evaluated using this method. As a result, this exercise has proven to be very valuable, not only for demonstrating the value of the log data, but also it has also highlighted some significant limitations of the core in water-based mud and oil-based mud systems.