Sharif Digital Repository

Colloidal Gas Aphron (CGA) are finding increasing application in fields of science and engineering because of their distinctive characteristic. As interest in the application of CGA based fluids grows and in order to select the best procedure for using them in successful petroleum engineering operations, there is a need to gain a better understanding of the factors that affect their properties and behavior. This article discusses the rheological characterization, stability analysis and filtration properties of CGA based fluids for three bio-polymers and two ionic surfactant. The stability and filtration analysis were investigated with the static drain rate technique and API filtration tests,... 

Cellulose nanowhiskers (CNWs) prepared via TEMPO mediated oxidation are used as biodegradable filler in an epoxy matrix. Since CNWs are hydrophilic and epoxy is hydrophobic, amphiphilic block copolymer surfactants are employed to improve the interactions between the filler and the matrix. The surfactants used are Pluronics, a family of triblock copolymers containing two poly(ethylene oxide) blocks and one poly(propylene oxide) block. In this study, Pluronic L61 and L121 with molecular weight of 2000 and 4400 g/mol and hydrophilic to lipophilic balance of 3 and 1 respectively, are used and their effect on the dispersion of CNWs in epoxy is discussed. The hydrophilic tails of Pluronics... 

On the surface of bubbles rising in a surfactant solution the adsorption process proceeds and leads to the formation of a so called Rear Stagnant Cap (RSC). The larger this RSC is the stronger is the retardation of the rising velocity. The theory of a steady RSC and steady retarded rising velocity, which sets in after a transient stage, has been generally accepted. However, a non-steady process of bubble rising starting from the initial zero velocity represents an important portion of the trajectory of rising, characterized by a local velocity profile (LVP). As there is no theory of RSC growth for large Reynolds numbers Re « 1 so far, the interpretation of LVPs measured in this regime was... 

This work aims to discuss the results of wide ranges of laboratory investigations to evaluate the performance of a newly-formulated surfactant for heavy oil reservoirs in order to improve the microscopic sweep efficiency after water flooding processes. In the first part, the specific behavior of the formulated surfactant including its salinity tolerance, interfacial tension, and optimum performance window was determined. Then, the application of surfactant solutions in real sandstone reservoir rocks was assessed for both oil-wet and water-wet cases. Besides, the effect of changing the capillary and viscous forces and interfacial tension on the residual phase saturations were characterized.... 

Plenty of oil reservoirs contain discontinuous shale layers that act as flow barriers. Therefore, understanding their influences on reservoir performance, especially during enhanced oil recovery (EOR) processes, is of great importance. For this purpose, several experiments of water and alkaline-surfactant-polymer (ASP) flooding have been performed on a number of one-quarter five-spot micromodels that contain various configurations of shale layers to simulate shaly porous media. Several features, such as various shale geometrical characteristics and the presence of connate water saturation, were investigated at both macro- and micro-scales. The presence of shales resulted in earlier... 

Although Alkaline-Surfactant-Polymer (ASP) flooding is proved to be efficient for heavy oil recovery, the displacement mechanisms/efficiency of this process should be discussed further in fractured porous media especially in typical waterflood geometrical configurations such as five-spot injection-production pattern. In this study, several ASP flooding tests were conducted in fractured glass-etched micromodels which were initially saturated with heavy oil. The ASP flooding tests were conducted at constant injection flow rates and different fracture geometrical characteristics were used. The ASP solutions constituted of five polymers, two surfactants and three alkaline types. The results... 

In this study, we have investigated the potential of a native bacterial strain isolated from an Iranian oil field for the production of biosurfactant. The bacterium was identified to be Bacillus mycoides by biochemical tests and 16S ribotyping. The biosurfactant, which was produced by this bacterium, was able to reduce the surface tension of media to 34 mN/m. Biosurfactant production was optimized by the combination of central composite design (CCD) and response surface methodology (RSM). The factor selected for optimization of growth conditions were pH, temperature, glucose and salinity concentrations. The empirical model developed through RSM in terms of effective operational factors... 

In this work, simultaneous inferential control of particle size distribution (PSD) and molecular weight distribution (MWD) in a semi-batch emulsion polymerization reactor of styrene has been addressed. Using a comprehensive dynamic model for PSD and MWD predictions and performing a sensitivity analysis, it has been revealed that free surfactant and chain transfer agent (CTA) concentrations in the reactor are the most suitable candidates for inferential control of PSD and MWD, respectively. To control concentrations of these species in the reactor, their inlet feed flow rates are used as manipulated variables. It is assumed that the concentration of CTA is measured infrequently and therefore... 

The effect of an efficient biosurfactant produced from Pseudomonas aeroginosa MR01, a bacterial strain isolated from oil excavation areas in southern Iran, on the recovery of residual oil trapped within carbonate rocks, was investigated. In a core holder set-up, bearing a number of limestone-and dolomite-containing core samples, biosurfactant flooding resulted in oil recoveries as large as 20% to 28% Residual Oil (R.O). Biosurfactant injection in less permeable rocks in a range of 0.5 to 32 md was more successful, in terms of oil production. In the case of the least oil recovery via biosurfactant flooding, incubation of the core with a biosurfactant solution at reservoir conditions,... 

Through a fast, simple, low cost, surfactant-free and convenient microwave-assisted route, narcis-like ZnO nanostructures (10-15 nm size) with flower diameters in the range of 1-2.5 μm were synthesized. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and room temperature photoluminescence (PL) measurements were used to characterize the produced ZnO nanostructures. The principle raw materials - ammonium hydroxide (NH4OH) and zinc acetate dihydrate [Zn(CH3COO)2·2H2O] - were both inexpensive. The method was fast, simple and surfactant-free capable of producing larger quantities of zinc oxide... 

The physical properties and chemical structure of a new biosurfactant (licheniformin) produced by Bacillus licheniformis MS3 were investigated. The purified biosurfactant was identified as a lipopeptide with amino acid sequence of Gly, Ala, Val, Asp, Ser, Gly, Tyr and a lactone linkage between the carboxyl group of Aspargine and hydroxyl group of Tyrosine residue. The fatty acid moiety was attached to N-terminal amino acid residue through an amide bond. The purified licheniformin could lower the surface tension of water from 72 to 38 mN/m at concentrations higher than 15 μg/mL and its relative emulsion volume (EV%) was equal to 36%. It also showed stable surface activity over a wide range of... 

This paper concerns with the interfacial tension (IFT), wettability modification and adsorption behavior of a new plant-based surface active agent, Zizyphus Spina Christi, onto sandstone minerals which has been rarely attended in the available literature. Both kinetics and equilibrium adsorption data were obtained from batch mode tests. It was revealed that Freundlich isotherms matched better fit to the equilibrium data which implied that multilayer coverage of Zizyphus Spina Christi onto the sandstone particle surfaces was more likely to occur. Analysis of experimental kinetic data based on intraparticle diffusion model disclosed that the intraparticle diffusion mechanism is not the only... 

A large amount of the discovered oil reserves are reserved in carbonate formations, which are mostly naturally fractured oil-wet. Wettability alteration towards more water-wet state reduces the capillary barrier, hence improving the oil recovery efficiency in such reservoirs. In this study, wettability alteration towards favorable wetting state was investigated by combining modified low salinity brine with surfactant during water flooding. The diluted brine was modified by increasing the concentration of Mg2+ and SO4 2−, individually as well as both ions in combination. Different brine formulations were tested experimentally through the observations of contact angle measurements and... 

The modification of the surface wetting characteristics in fractured oil-wet carbonate reservoirs, by reversing wettability from oil-wet to water-wet, leads to improved oil recovery. However, in order to obtain a successful oil recovery process, it is crucial to understand the active mechanisms of wettability alteration. This study looks at the effect of sulfate ions as one of the most promising wettability influencing ions on the wetting properties of oil-wet calcite; the effect is studied both with and without the presence of cationic surfactant and possible mechanisms of wettability alteration are explored. A number of analytical techniques were utilized to analyze the mineral surface... 

The aim of this study is to simulate the self-assembly of the surfactant molecules with special chemical structure and bending stiffiness into bilayer membranes using a mesoscopic Dissipative Particle Dynamics (DPD) method. The surfactants are modeled with special chemical structure and bending stiffiness. To confirm that the novel model is physical, we determine the interaction parameters based on matching the compressibility and solubility of the DPD system with real physics of the uid. To match the mutual solubility for binary uids, we use the relation between DPD parameters and x-parameters in Flory-Huggins-type models. Unsaturated bonds can change the stiffiness of a lipid membrane,... 

Ni-TiN nanocomposite coatings were prepared by using electrochemical deposition in a Watt's bath containing TiN particles to increase the hardness of Ni. The effects of deposition current density, electrolyte agitation speed and the number of particles in the solution on the amount of incorporated particles in the coating process were investigated. The optimum deposition current density of 4 A dm-2 and agitation speed of 450 rpm were obtained. The effect of sodium dodecyl sulphate (SDS) anionic surfactant on the amount of particles in the coatings was investigated. It was observed that the maximum amount of incorporated particles, with a value of 7.5% by volume, was created in the current... 

CO2 injection has proved to be the most common and efficient enhanced oil recovery techniques which leads to more residual oil recovery. Unfavorable sweep efficiency which results in fingering propagation and causes early gas breakthrough is the most challenging issue of gas flooding process. The aim of this work is to study foam stability and analyze the mobility of CO2 foam stabilized by mixture of raw silica nanoparticles and ethyl hexadecyl dimethyl ammonium bromide (cationic surfactant). The result is obtained through both dynamic and static techniques using a new adsorption index.NPS-stabilized foams are generated using Ross-Miles method. A novel index for the adsorption of surfactant... 

This study deals with the large-scale production of biosurfactant from soybean oil soapstock by Pseudomonas aeruginosa MR01. The production of biosurfactant was carried out in a newly designed bioreactor equipped with recycling flow under three operational conditions. Kinetic studies were conducted at both shake flask and 5-L bioreactor scales during fermentation in a soapstock medium. Mathematical equations were developed to model the kinetic patterns at both scales. RESULT: Statistical analyses demonstrated the goodness of fit, with regression r-squared, R2, between 0.97and 0.99 for different models. Furthermore, biosurfactant concentration in the bioreactor including the recycling flow,... 

Although alkaline-surfactant-polymer (ASP) flooding has proven efficient for heavy oil recovery, the displacement mechanisms and efficiency of this process should be discussed further in fractured porous media. In this study, several ASP flooding tests were conducted in fractured glass-etched micromodels with a typical waterflood geometrical configuration, i.e. five-spot injection-production pattern. The ASP flooding tests were conducted at constant injection flow rates but different fracture geometrical characteristics. The ASP solutions consisted of five polymers, two surfactants, and three alkaline types. It was found that using synthetic polymers, especially hydrolyzed polyacrylamide... 

The strength of a newly formulated surfactant with an alkali and polymer (AS/ASP) to improve an acidic heavy oil recovery was laboratory evaluated by various flooding experiments. The comparative role of the parameters like chemical nature, surface wettability, salinity, temperature and injection scheme were explored at high temperature and pressure on Berea sandstone rocks. According to the results the anionic surfactant is capable of providing proper oil displacement under high salinity conditions around 15 wt%. Continuous monitoring of differential pressure response and effluents’ state clearly represented the formation of an emulsified oil in high saline solutions with both alkali and...