Sharif Digital Repository

Asphaltenes, and their related issues, have been the focus of many literature investigations. However, in-depth analysis of asphaltenes structure and its relation to asphaltenes stability has been considered by fewer studies. In this research, extensive analysis of the structure of asphaltenes extracted from light, medium, and heavy oils is provided, together with analysis of three subfractions of the medium oil asphaltene having the least, intermediate, and highest solubilities. To this end, elemental analysis, EDX, mass spectroscopy, FTIR, NMR, XRD, and SEM results were collected. Higher hydrogen content and hydrogen/carbon atomic ratio, lower aromatic nature and olefinic entities were... 

Despite many attempts to study the interaction of fluids in low-salinity flooding, they do not examine the principles of interphasic transition phenomena. This study aims to provide a new understanding of liquid–liquid interactions during the low-salinity water interaction through a series of experiments on the oil, emulsion, and aqueous phase. Three samples of crude oils with different asphaltene concentrations and structures with known physical properties are in contact with different solutions. The brine pH, conductivity, and crude oil viscosity experiments before and after contacting the oil with brine showed that the heteroatom concentration and compaction of crude oil asphaltene... 

One of the significant problems of the upstream flow assurance community is precipitation or deposition of asphaltene that leads to affect the economics of oil production seriously. Knowledge of asphaltene onset pressure (AOP) and amount of asphaltene precipitation in the change of temperature, pressure, and composition is the essential information for preventing this problem. Recent studies have shown that thermodynamic models based on the solubility nature of asphaltenes using an equation of state (EOS) are the most effective approach to asphaltene behavior modeling. In this research, the common version of the SAFT equation, known as the Perturbed Chain form of Statistical Association... 

In the last decade, there has been a swift development in several scientific research works in which the quartz crystal microbalance (QCM) technique has played a critical role in unravelling different aspects of energy and environmental materials and biological substances as well as all corresponding molecular interactions within those media. We comprehensively review the numerous types of surface chemistries, including but not limited to hydrogen bonding, hydrophobic and electrostatic interactions, self-assembled monolayers and ionic bonding, that are monitored using QCMs in a variety of fields such as energy and chemical industries in addition to the biology, medicine and nanotechnology... 

One of the possible fluid-fluid interactions during water-flooding in oil reservoirs, that is still debated, is the effect of injected brine salinity on asphaltene destabilization. If asphaltene precipitation is induced by salinity changes in the oil reservoirs and surface facilities, this could have a massive impact on the economy of a low salinity water-flooding project. Therefore, this study aims to investigate the effect of brine salinity on the amount of asphaltene precipitation and the governing destabilization mechanisms. Direct asphaltene precipitation measurements, along with the analyses of optical microscopy images and ion chromatography (IC), indicate that the asphaltene... 

Onsite partial upgrading is a promising strategy for facilitating pipeline transportation of bitumen without the use of diluent. In the present work, a one-step treatment using an autoclave is optimized toward upgrading Alberta bitumen of 9.6 API gravity and 925,000 cP viscosity. The thermal cracking process was kept simple in order to maintain an economic and environmental advantage. Optimum conditions entailed 75 min of reaction time at 420 °C, without quenching the reactor. These conditions corresponded to highest centrifuged oil product yield of 73.3 ± 1.1 wt%, viscosity of 34 ± 2 cP and API gravity of 18.9 ± 0.5. H-NMR, CHNS and FTIR measurements revealed thermally cracked asphaltenes... 

In this study, a series of heteroatoms including nitrogen, oxygen, and sulfur were added to different positions of the model asphaltene structure to study the effect of the heteroatom presence in the self-aggregation of the model asphaltenes. Molecular Dynamics was used to calculate Solubility Parameters, Radial Distribution Function, and Relative Solubility Parameters. Additionally, Reactivity Parameters, Electrostatic Potential, Reduced Density Gradient, and Independent Gradient Model were calculated using the Density Functional Theory to further investigate the Molecular Dynamics results. This study indicated that heteroatoms' diversity and their positions in the model asphaltene... 

The role of emulsions as a prevalent phenomenon is broadly investigated in the petroleum industry since forming the emulsion has many severe harmful implications. Heavy components of crude oil such as wax and asphaltene make the water-in-oil (w/o) emulsion more stable, while the role of these components on the emulsion viscosity has not been fully understood. In this regard, to find a proper demulsifier to break these emulsions, it is necessary to know the mechanisms of emulsion formation by heavy oil components. In this study, the effects of waxy-oil and asphaltenic-oil on w/o emulsion were investigated by measuring volume and viscosity of the formed emulsion after an elapsed time, followed... 

Deposition of asphaltenes upon precipitation is a main flow assurance concern, which propelled the development of various experimental and modeling techniques to accurately predict its occurrence. This work develops an integrated approach combining thermodynamic and deposition modules with a multiphase flow simulator to simultaneously model asphaltenes precipitation and deposition in wellbores. The Peng-Robinson equation of state and the modified Miller-Flory-Huggins theory are used to calculate the thermodynamic properties of the oil and asphaltenes precipitation, respectively. The deposition module is based on conservation laws for asphaltenes transport and is linked to the flow simulator... 

This research aims to present asphaltene fraction of oil by FTIR spectrum technique. For this purpose, three different oil samples with various SARA contents and almost identical API degrees were utilized in this research. Two asphaltenic oil samples were referred to as ‘A’ and ‘B’, and the aliphatic oil sample was named as ‘C’. First of all, the asphaltene fraction was extracted through the IP-143 test. The possible chemical bonds and functional groups were identified through NMR tests. Then, the FTIR spectrums of the oil samples and the extracted corresponding asphaltene fractions were taken. The interpretations were used to find the functional groups in the FTIR of the oil samples that... 

Asphaltene deposition during enhanced oil recovery (EOR) processes is one of the most problematic challenges in the petroleum industry, potentially resulting in flow blockage. Our understanding of the deposition mechanism with emphasis on the rate of the asphaltene deposition is still in its infancy and must be developed through a range of experiments and modelling studies. This study aims to investigate the rate of asphaltene deposition through a visual study under different gas injection scenarios. To visualise the asphaltene deposition, a high-pressure setup was designed and constructed, which enables us to record high-quality images of the deposition process over time. Present research... 

Abstract: This study investigates the catalytic activity of mixed–metal oxide nanoparticles with different surface acidities on asphaltene adsorption followed by catalytic oxidation–decomposition. Three different types of mixed–metal oxide nanoparticles (CeNiO3, CeCaO3 and CeZrO4) were synthesized, and their size, structure, and acid properties were characterized by field–emission scanning electron microscopy (FE–SEM), energy-dispersive X-ray spectroscopy (EDX), the high–resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurement and ammonia temperature-programmed desorption (NH3–TPD). Asphaltenes were extracted... 

Minimum Miscibility Pressure (MMP) is regarded as one of the foremost parameters required to be measured in a CO2 injection process. Therefore, a reasonable approximation of the MMP can be useful for better development of injection conditions as well as planning surface facilities. In this study, the impact of asphaltene content ranging from 3.84 % to 16 % on CO2/heavy oil MMP is evaluated. In this respect, slim tube miscibility and Vanishing Interfacial Tension (VIT) tests are used. Regarding the VIT test, the Interfacial Tension (IFT) is measured by means of two methods including pendant drop and capillary apparatuses, and thereafter the MMP measurement error between slim tube and VIT... 

As expounded, the precipitation and deposition of asphaltene particles in pipelines has been proved to be the most challenging flow assurance problem due to its unknown and complex behaviors. In this work, a new multicomponent, multiphase and dynamic tool was developed to model the aggregation and deposition of asphaltene particles in a bulk medium. The multiphase and dynamic asphaltene deposition tool, shortened as MAD-ADEPT is, in fact, a modified version of the previously developed ADEPT. The new tool was developed to make the asphaltene deposition and aggregation concepts in oil production wells more predictable. To tackle the complexity of the asphaltene problem, a bespoke algorithm was... 

In this work, high-pressure microscopy technique was used to measure the size and fractal dimension of asphaltene aggregates formed in different live oil samples at elevated pressures and temperatures. It was found that the asphaltene aggregates in live oil samples are irregular fractal-like structures with pressure−temperature-dependent fractal dimensions. By monitoring the variation of the fractal dimension and size of the asphaltene aggregates with pressure and temperature, the mechanisms responsible for asphaltene aggregation process at elevated pressures and temperatures can be well predicted. The range of fractal dimension of asphaltene aggregates in live oils is similar to that... 

Understanding the roles of asphaltene and resin as natural surfactants existed in crude oil can enlighten contradicting reported results regarding interfacial tension (IFT) of crude oil/aqueous solution as a function of salinity and ion type. In this way, this study is aimed to investigate the effect of these natural surface active agents on IFT of with special focus on SO42− anion and Mg2+ cation. Two different synthetic oil solutions of 8 wt% of the extracted asphaltene and resin dissolved in toluene are prepared, and then IFT values are measured. After that, the obtained results are compared with the IFT of intact crude oil in contact with the same saline solutions examined in the... 

Asphaltene precipitation and deposition causes many serious problems to the petroleum industry from the reservoir to the surface facilities. Therefore, it is important to bring it under control by finding a method to accelerate or slow down its precipitation and deposition. For achieving this purpose two parameters play an important role; onset point of the precipitation and amount of the deposited phase. When asphaltene precipitates, it is capable of depositing in the solution. After the deposition, the solution split into two phases; asphaltene-rich and asphaltene-lean. Determining the amount of the deposited phase needs to distinguish the interface between two phases. In this study, a... 

This research aims to propose a thermodynamic model for predicting asphaltene precipitation upon diluting a crude oil with a paraffinic solvent. To this end, a thorough mathematical formulation was carried out to derive a novel micellization model based on the associative properties of asphaltenic compounds. It was assumed that asphaltenes exist in the oil both as monomeric molecules and aggregated cores; with stabilization latter by attachment of resin on its periphery. The aggregation equilibrium was established by taking into account asphaltene's lyophobic tendency, heat of resin adsorption, and interfacial tension between micelle and oil media which is the main driving factor... 

Molecular dynamics (MD) simulation was utilized to study the role of asphaltene extracted from Gachsaran (an Iranian oilfield) at the synthetic oil-water interface. In agreement with experimental data, IFTs predicted by MD simulation for heptol/brine system showed a minima at around 50 vol.% n-heptane, reflecting the highest contribution of asphaltene into the interface. At greater n-heptane fractions, IFT was increased steadily. Simulation results suggest the asphaltene propensity for remaining in the bulk heptol phase rather related to the fraction of toluene in the mixture. Heptol ingredients, i.e., toluene and heptane, act differently with respect to asphaltene, where former tends to... 

In this study, the dynamic adsorption of asphaltene on a calcite surface is investigated. This study investigates the effect of mixed-salt brines on asphaltene adsorption. The results of this work can facilitate the understanding of the complex wettability behaviour of carbonate reservoirs. All experiments were performed in porous media, which were sand-packs filled with calcite powder, to study the influence of the type and concentration of salt on adsorption. The experiments were conducted with asphaltene concentration of 500 mg/L for brines of NaCl, Na2SO4, and a mixture of the two at various ionic strengths. In addition, two tests were performed with an asphaltene concentration of 2000...