جستجوی مقالات مرتبط با کلیدواژه « آسفالتین » در نشریات گروه « مهندسی شیمی، نفت و پلیمر »

Interfacial tension (IFT) is one of the most important parameters that directly affects the capillary forces, which affects oil recovery. This research investigates the effects of asphaltene concentration and water-soluble divalent ions on IFT. A mixture of toluene and n-heptane, which is called heptol, is used as the model oil, and then asphaltene was added into Heptol to study its effect on the surface-active properties of the model oil. Brine in a salinity of sea water (SW) with a concentration of 40,000 ppm was considered as the base aqueous phase. A diluted brine with a concentration of 4000 ppm was prepared as a low salinity water (LSW), and a concentrated 80,000 ppm aqueous solution is considered high salinity water (HSW). Afterwards, the dynamic IFT of the oil phase/aqueous phase interface was measured using the pendant drop method. Results show that with the increase in the asphaltene concentration, IFT of heptol/brine system was decreased. The lowest value of IFT was observed in the salinity of 40,000 ppm. This may show an optimum salinity range to facilitate migration of asphaltene molecules into brine/heptol interface, which led to an IFT reduction from 23 to 16 mN/m. Results indicated that an asphaltene concentration of 0.5% can be was considered as the critical micelle concentration. At the end, the effect of divalent ions, i.e. calcium, magnesium and sulfate ions in the aqueous phase was investigated, and it is shown that the calcium ion has a larger effect on IT reduction compared to the magnesium and sulfate ions.

The dielectric properties of a substance are the properties by which the effect of the utilization of electromagnetic waves can be studied. These properties should be investigated to study the electromagnetic heating method and optimization. In this study, seven oil samples from different fields were investigated, including Asmari, Sarvak, Sohrab, Fahlian, Kuh Mond, Mansouri, and Yaran. In this study, organic compounds and functional groups in crude oil were identified, and their effect on the dielectric property of oil was investigated. By examining the parameters affecting the dielectric property, it was concluded that the more polar compounds the compound has, the higher the dielectric and, therefore, the higher the ability to absorb microwave waves. The amount of dielectric property of Kuhmand, which is part of super heavy oil equal to 2.853 and Fahlian which is part of light oil is equal to 2.006, which shows that the heavier the oil between these two oil samples, the more Its electricity is higher and ultimately has a higher ability to absorb electromagnetic microwave waves. On the other hand, the bonds in the oil themselves also affect the dielectric. According to the FTIR test, the OH, NH, CN and SH bonds in the samples are directly related to the dielectric. The higher the concentration of these bonds is, the higher the dielectric is. In this project, the required links and functional groups within oil samples have been studied and discussed.

Asphaltene precipitation, as stated in previous studies, plugs the pores in the porous media and causes various problems, including permeability reduction, wettability alteration, and ultimately reduces production. The results of this study showed that this surfactant is able to prevent asphaltene precipitation and is effective in different aqueous phases (DW, SW and CW). In addition to increasing recovery factor in the core flooding test, it was able to alter the wettability of the pores surface from oil-wet to intermediate.

This study aims to investigate a new method of combining ultrasonic waves with different frequencies and magnetic nanoparticles in reducing the asphaltene content and kinematic viscosity of heavy oil. In the first section, in order to upgrade heavy oil, the oil was subjected to ultrasonic waves with different frequencies at constant temperature of 20 °C. In the next section, the temperature of experiment and the layout of 1.7 MHz piezoelectric transducers were optimized, in dual frequency radiation. In the final section, in presence of fixed magnetic field, the effect of combining of ultrasonic irradiation in dual-frequency mode with Co2O3 and magnetic γ-Fe2O3 nanoparticles on the kinematic viscosity and asphaltene content of the heavy crude oil was studied. The experimental optimizations cleared that in the presence of magnetic field and ultrasonic waves irradiation with dual frequency, the γ-Fe2O3 magnetic nanoparticle had a better performance than Co2O3 nanoparticle, so that at the optimum concentration (0.4 wt.%), the asphaltene content and kinematic viscosity were significantly declined to 5.01 wt.% and to 7.1 cSt  respectively.

Asphaltenes are heavy components in oil that do not dissolve in normal alkanes like normal heptane but can be soluble in aromatic compounds such as benzene and toluene. Usually changes in operating conditions such as temperature, pressure and fluid composition lead to asphaltene precipitation. Asphaltenes cause a lot of damage by depositing in porous media, wells, pipes and surface equipment. In order to prevent or postpone the formation of asphaltene precipitation in different conditions and places, it is very necessary and important to predict the onset point and the amount of precipitation. Temperature, pressure and flow rate are operating conditions that by changing each, the amount of precipitation can be reduced or intensified. The only solution in the industrial world to postpone asphaltene precipitation is to use chemicals and inhibitors, which is very important to know the mechanisms of deposition. In this review paper, the structure of asphaltene, deposition conditions, experiments of asphaltene precipitation, deposition mechanisms and inhibitors are discussed. The main purpose of this article is general acquaintance with asphaltene precipitation and the factors affecting deposition and applying knowledge to prevent the formation of asphaltene precipitation with the approach of using and applying inhibitors.

Asphaltene precipitation/deposition in reservoir formation has detrimental influences on the oil production. The stability of w/o emulsions, the high viscosity of oil, and unfavorably changing the reservoir rock properties are induced in part by the asphaltene instability. Nanoparticles exhibit acceptable capacities for the adsorption and control of the precipitation of asphaltene. In this study, in-situ synthesis of iron oxide nanoparticles in reservoir oils has been followed to evaluate the effects of the thus-prepared nanoparticles on the control of asphaltene damage in tight carbonate core plugs. Model oil has been prepared by dissolving dead oil in a toluene/gasoil mixture. Following the preparation of stable emulsions of precursor iron salt aqueous solution in the model oil, Fe2O3 nanoparticles have been synthesized at a typical reservoir temperature and high-enough pressure in an autoclave. Two series of core-flooding experiments have been performed by the injection of n-C6 and monitoring the hydrocarbon effective permeability before and after the damage. Two core plugs with the same flow zone index have been selected, one of which has been saturated with the model oil and the other with the emulsion, and the asphaltene damage has been induced by the core flooding test. The results of XRD and FESEM have indicated the crystalline structure and the mean particle size of 65 nm for the in-situ prepared nanoparticles, much smaller than the pore/throat sizes of the plugs. It is found out that the nanoparticles are effective in the control of the asphaltene damage at high injection/production flowrates. However, at low drawdown or injection/production flowrates, the in-situ synthesis procedure leads to a higher drop in the hydrocarbon effective permeability when compared to that observed during the displacement of the virgin model oil. Finally, this may be ascribed to the trapping of aqueous droplets in pore-throats, resulting in a significant reduction in the hydrocarbon permeability by the phase trapping.

The asphaltene molecules play a very important role in the crude oil for the exteraction of oil from oil reservoirs. Therefore, in this study, the aggregation and deposition of asphaltene N6 in aromatic solvents such as cyclohexane, benzene, toluene, chlorobenzene and bromobenzene were investigated by using molecular dynamics simulation at room temperature and pressure. In addition, physical properties such as density and solubility parameter for N6 asphaltene and pure solvents were calculated and compared with experimental data. There is a good agreement between the simulation results and experimental data. In addition, the behavior of asphaltene molecules was studied for pure and soluble in aromatic solvents conditions. The results show that the asphaltene molecules aggregate due to π-π bonds between the aromatic rings in the structure of them. Finally, the simulation results indicate that the asphaltene molecules are soluble in chlorobenzene better than other solvents, and also it is better than toluene solvent.

Dwindling of conventional oil reserves and increasing global demands have caused increased exploitation of heavy crudes accounting for a large fraction of the world's crude oil resources. Formation of stable water-in-crude oil emulsions in hydrocarbon reservoirs or in production processes are inevitable increasing environmental problems as well as costs of transportation and refining. Heavy crude oil viscosity also makes several problems during extraction and transportation. Viscosity reduction processes of heavy crude oil for pipeline transportation have been subject of many researches. In this paper, challenges involved in use of these energy resources have been evaluated using a comprehensive literature review.

Asphaltene deposition is one of the main problems in crude oil production. Using of asphaltene dispersants and inhibitors are one of the effective methods for preventing deposition of asphaltene particles. Acids are an important class of chemical compounds that could reduce asphaltene problems, regarding to the polarity of asphaltenes and acid molecules. Their efficiency is related to the amount of asphaltene-acid interaction. In this study, the amount of the interaction of acids and their binary mixtures was studied with extracted asphaltene from Iran crude oil by using UV-vis spectroscopy. Different acids were examined that included mono and multi-functional acids. In this method, decreasing the UV absorbance was assisted as index for the amount of the interaction of acids with asphaltene in the asphaltene-toluene solution with the presence of aqueous solution of acids and their binary mixtures. Solubility performance of acids and their binary mixtures was compared for reducing the amount of asphaltene precipitation by changing their mole volume. Experimental results show that the interaction of asphaltene-acids increases with increasing the amount of acid. Among the all studied acids, Interactions of adipic acid and oxalic acid with asphaltene are more than of other acids. The effect of acids binary mixture also investigated on asphaltene precipitation. Results of experiments show that the binary mixtures which is containing para-toluene sulfonic acid has the most interaction with asphaltene particles to reduce amount of precipitation.

Asphaltene deposition is one of the main problems in asphaltenic oil fields. In this study, asphaltene deposition from crude oil has been studied experimentally using a test loop using an accurate temperature monitoring technique during Turbulent flow. The effects of oil velocity, surface temperature and the concentration of flocculated asphaltene on the rate of asphaltene deposition are investigated. The results show that asphaltene deposition rate increases by increasing both surface temperature and concentration of flocculated asphaltene. As the oil velocity increased, less deposition was noticed for the tests performed in this experimental study. The models were used for measuring the rate of asphaltene deposition is based on fouling models for heat exchanger. These models have two terms, the deposition and removal terms. The deposition terms are the same in the all of the models but the rate of removal is described either by shear-related or mass-transfer related expressions. The results of the data fitting show or authenticate that there are good agreement between the predicted thickness and the experimental value. Besides, the models that include the mass transfer in the removal term show a good agreement between the model data and experimental data. Therefore, these models are suitable and reliable enough for predicting experimental data.

One of the challenges of the exploitation and production of oil from reservoirs is the deposition of asphaltene particles on the transfer surfaces; such as, porous media, wells and piplines. Knowing about the particle size of asphaltene, in the studies of solid mass transfer of fluid to the surface, is essential to estimate the location, amount and time of the scale. One of the questions wich has been studied less is «How do the sizes of asphaltene particles change at different thermodynamic conditions?» In this study, asphaltene instability in one of the iranian heavy oil was determined by SARA test, initially. Thermodynamic behavior of asphaltene was found through filtration tests in high pressure and temperature conditions. Then, using an optical microscope, the sizes and distributions of the asphaltene particles were measured at 12 temperature and pressure points. The experimental results showed that both particle sizes and distribution of particles are sensitive to temperature and pressure. The thermodynamic and microscopic results are matched appropriately. Finally, the obtained experimental results were modeled in the form of an empirical correlation. The results of this study could be as an integrated chain between thermodynamic behavior of the asphaltene and the transfer phenomena of the asphaltene deposition in the oil well column and reservoir porous media.

This paper presents the feasibility (or possibility) of removal of asphaltenes from aqueous solutions by using low-cost natural adsorbents; such as, light expanded clay aggregate (LECA), perlite and bentonite. The effect of adsorbent type, initial asphaltene concentration, particle size of adsorbent and temperature on the adsorption capacity was investigated. The results showed that at the initial asphaltene concentration of 125 mg L 1-, contact time of 24 hrs, temperature of °50C and adsorbent dosage of 1 g, removal of asphaltenes onto LECA, perlite and bentonite was 53.59, 93.01 and %99.77, respectively. Also, Langmuir and Freundlich models were applied to describe the experimental data; moreover, the results indicated a good fitting by Langmuir isotherm. Thermodynamic parameters; such as, ∆H, ∆S and ∆G were calculated. It was revealed that the adsorption was spontaneous and exothermic nature, which was evident by decreasing the randomness of the dye at the solid and liquid interfaces. The characteristic results and the dimensionless separation factor (RL) showed that perlite and bentonite could be employed as an alternative to commercial adsorbents in the removal of asphaltenes from aqueous solution and oil.

The impact of Co3O4 nanoparticles with concentration of 0.1 wt%has experimentally been studied on (1) interfacial tension, (2) asphaltene precipitation and (3) miscibility with the carbon dioxide, when the Co3O4 nanoparticles have been added to one of Iranian crude oils and synthetic oil solutions . To do so, the Vanishing Interfacial Tension (VIT) technique has been used for a pressure of up to 1200 psi. The results have been showed that in the presence of Co3O4 nanoparticles, IFT, Minimum Miscibility Pressure (MMP) and severity of asphaltene precipitation have all been reduced to some extent. Within the range of operating conditions attempted here, MMP has reduced as much as 32% and 19% for the synthetic and crude oils, respectively. The severity of asphaltene precipitation has also reduced approximately 13% for the asphaltenic synthetic oil and 7% for the investigated crude oil. The experimental results appear to show that Co3O4 nanoparticles served to adsorb asphaltene which would, in turn, facilitated the solubility of CO2 in synthetic and crude oils which consequently would lead to enhanced oil recovery.

Asphaltenes constitute the main hydrocarbon precipitants of crude oil which have been formed and deposited due to the effect of changing temperature, pressure and composition.. The phase separation of these heavy solid precipitates could alter rheological properties of reservoir fluids (e.g. by increasing pressure drop in pipes, reducing well productivity and ultimately stopping production). Detection of the time and location of phase separation is one of the major challenges in production assurance. To achieve this target, the thermodynamic conditions that induce precipitation of Asphaltenes in the oil medium (a.k.a. onset of precipitation) needs to be determined. On the other hand, the content of precipitation is important to characterize the thermodynamic behavior of Asphaltene. Viscosity is a reliable parameter for detection of phase separation Asphaltene precipitation in both onset point and content. In this study, the viscosimetry method is used for detection of onset of precipitation and the results are compared with that of other common methods of solid detection. The results indicate that the viscosity method has acceptable accuracy for crude oils with an API range of 18 to 40 and a wide pressure range (atmospheric to high pressure conditions). Solid solution theory is used for the modeling of thermodynamic behavior. In our study, Asphaltene is introduced as an individual component in Solid-Liquid-Vapor Equilibrium calculation. So rather than common solid model our modification take it easy to use the real physical properties of Asphaltene; such as, molecular weight and molar volume.

Asphaltene deposition is one of the main problems in asphaltenic oil fields.The aim of this work presents a model for predicting the rate of asphaltene deposition in flowing system. The model should be able to predict the effect of velocity, temperature on deposition rate. To study of asphaltene deposition in flowing system, a flow assurance type setup is needed. The models were used for measuring the rate of asphaltene deposition is based on fouling models for heat exchanger.These models have two terms, the deposition and removal terms. The deposition terms are the same in the all of the models but the rate of removal is described either by shear-related or mass-transfer related expressions.The results of data fitting show that there are good agreement between the predicted thickness and the experimental value.

One of the most important issues in EOR is asphaltene deposition. Asphaltene is partly dissolved in oil, partly in steric-colloidal form and partly in micellar form depending on the composition of crude oil. Adding dispersing agents to oil, which are functionally similar to natural resin, prevents the aggregation of asphaltenes in crude oil. Inhibition strength is a capability of the inhibitor to delay formation of asphaltene flocculates, which depends on the interaction between the inhibitor and asphaltene particles. In this study, the onset of asphaltene precipitation was evaluated using a viscometric method in the presence of three types of inhibitors. In order to determine stabilization (dispersion) strength, the context of “effective adsorption point” of inhibitor is introduced by the use of the shear effects of asphaltene aggregates. The results showed that the inhibitor was adsorbed on asphaltene micelles and the stabilization strength increased with increasing inhibitor concentration. The comparison between colloidal instability index (CII) and the stabilization strength of the inhibitor indicated that the inhibition and stabilization strengths of the studied inhibitors were much higher than the natural resins.

Nanotechnology is of significant importance in many scientific fields. In view of engineering problems, nanomaterials have found wide practical applications. In this work, iron oxide nanoparticles called maghemite (γ-Fe2O3) were synthesized. The synthesized nanoparticles were used to adsorb asphaltene from prepared asphaltene-toluene solutions. Asphaltene adsorption kinetic behavior was modeled using experimental data. For the synthesis of maghemite nanoparticles, the co-precipitation of ferric and ferrous ions method as a simple and inexpensive method was selected. The crystalline structure and morphology of synthesized maghemite was investigated using X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. The nanoparticles were also characterized by using FT-IR spectrum. The results of these analyses showed that the γ-Fe2O3 nanoparticles had a crystalline structure with a size smaller than 50 nm and were spherical in shape. The maghemite nanoparticles were used for the adsorption of asphaltenes. The results obtained from adsorption kinetics analysis showed that asphaltene was rapidly adsorbed onto γ-Fe2O3 nanoparticles, and equilibrium was achieved in less than 2 hrs. The Lagergren pseudo-first-order and the pseudo-second-order models were employed for determination of the adsorption kinetics. It was found that the kinetic results were in good agreement with the pseudo-second-order model.