Erfan Mohammadian

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.

Application of extreme learning machine for prediction of aqueous solubility of carbon dioxide

Solubility of CO2 in brine is one of the contributing trapping mechanisms by which the injected CO2 is sequestrated in aquifers. In the literature, the solubility data on low salinity range are scarce. Thus, in the current study, the CO2 solubility was experimentally obtained in the NaCl brines of low salinity (0–1.5xa0wt%) at temperature of 333–373xa0K and pressures up to 280xa0MPa through the potentiometric titration methods. The short-term, multistep ahead predictive models of aqueous solubility of carbon dioxide were created. The models were developed using a novel method based on the extreme learning machine (ELM). Estimation and prediction results of the ELM model were compared with the genetic programming (GP) and artificial neural networks (ANNs) models. The results revealed enhancement of the predictive accuracy and generalization capability through the ELM method in comparison with the GP and ANN. Moreover, the results indicate that the developed ELM models can be used with confidence for further work on formulating a novel model predictive strategy for the aqueous solubility of carbon dioxide. The experimental results hinted that the current algorithm can present good generalization performance in the majority of cases. Moreover, in comparison with the conventional well-known learning algorithms, it can learn thousands of times faster. In conclusion, it is conclusively found that application of the ELM is particularly promising as an alternative method to estimate the aqueous solubility of carbon dioxide.

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.

Effects of ultrasonic waves on carbon dioxide solubility in brine at different pressures and temperatures

The adverse impacts of CO2 emission on the global warming highlight the importance of carbon capture and storage technology and geological storage of CO2 under solubility trapping mechanisms. Enhancing the solubility of CO2 in formation water has always been the focus of research in the area of CO2 sequestration. Ultrasound techniques are one of the environmentally friendly methods that use high-intensity acoustic waves to improve gas solubility in liquids. Ultrasonic waves can alter the properties of different phases that lead to chemical reactions and provide a means to increase the solubility of CO2 in connate water. In this study, we investigated the effects of ultrasound on the solubility of CO2 in connate water under different conditions of pressure, temperature, and salinity. The results showed that the solubility of CO2 was improved with increasing pressure under ultrasonic effects. However, the solubility of CO2 was inversely proportional to the increase in brine salinity and temperature. Therefore, it was concluded that the solubility of CO2 might be enhanced in the presence of ultrasound.

Micellization and Synergistic Effect in an Aqueous Solution of an AOS-TX100 Mixture: Before and after Equilibrium in the Presence of Clay

In this research, a novel surfactant mixture consisting of anionic (alpha olefin sulfonate [AOS]) and nonionic (TX100) type was developed. Possible synergistic effect in micelle formation in different mass ratios of the mixture (1:2, 1:1, and 2:1) was studied by surface tension measurement method. Rubinghs Regular Solution theory was used to evaluate the interaction parameters (β) and activity coefficient (f) for both binary mixture and single surfactants, before and after equilibrium in the presence of clay minerals (kaolinite and illite). The differences between experimentally obtained CMC values and ideally calculated values, showed nonideality of the mixtures. In addition, the lower CMC values of mixtures in comparison with individual surfactants were an indication of synergism. The synergistic effect was maintained before and after equilibrium with clay minerals. The β values of the mixture before equilibrium were in the range –1.5 to –2.6. However, after equilibrium with kaolinite, the values were in the range of –1.9 to –3.9 while after equilibrium with illite they were in the range –1 to –3. For the mixture, before and after equilibrium, the synergism became more severe as mole fractions of AOS increased in the mixture.

Investigation of pH Impacts on Mineralization of CO2 in Conditions Representative of the Malay Basin

This paper discussed effects of temperature, pressure salinity and presence of rock and pH behavior of the system and formation of carbonates. Experiments are conducted in a high pressure high temperature reactor and effluents were collected, weighed and photographed using SEM. The aim of this research was to enhance the knowledge about mineralization mechanisms of CO2 sequestration in saline aquifers.

A role of ultrasonic waves on oil viscosity changes in porous media

Theoretically, ultrasound method is an economical and environmentally friendly or “green” technology, which has been of interest for the purpose of enhancement of oil/heavy-oil production. However, in spite of many studies, questions about the effective mechanisms causing increase in oil recovery still existed. One of the changes that could be recognized in the fluid properties is viscosity reduction due to radiation of ultrasound waves. In this study, a technique was developed to directly investigate the effect of ultrasonic waves (frequencies of 25, and 68 kHz and powers of 100, 250, 500 W) on viscosity changes of Paraffin, Synthetic oil, and Kerosene. The experiments were carried out for uncontrolled and controlled temperature conditions in a smooth capillary tube. The viscosity of all the liquids was decreased under ultrasound in all the experiments. Cavitation and heat generation are identified as influencing mechanisms on oil viscosity reduction under ultrasound. The effect of ultrasound frequency, power and temperature on viscosity reduction is also discussed in this article.

Formation of carbonates and PH variations in conditions representative of deep saline aquifers

CO2 sequestration in saline aquifers has been of interest as an option to reduce concentration of CO2 in the atmosphere. Of all the mechanisms of sequestration, mineral sequestration is proved to be the most secure one. In this study, formation of carbonates is investigated through monitoring of PH of the medium consist of sand+synthetic brine+ supercritical CO2 and sand+synthetic brine+ supercritical CO2. The experiments are conducted at pressures of 1100 and 1300 psi (CO2 at supercritical state) and temperatures ranged from 70-150. The results indicated that salinity of brine, pressure and temperature of the system directly affect the PH of solution and therefore formation of carbonates.