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Experimental data of density have been measured for binary liquid mixtures containing {amines (n-butylamine, or s-butylamine, or t-butylamine, or diethylamine, or propylamine) + water}, over the entire range of composition at temperatures between 283.15 and 303.15 K, and atmospheric pressure. The density values enabled the determination of the thermal expansion coefficients. The excess molar volume, $${\text{V}}_{\text{m}}^{\text{E}}$$ , was calculated using the experimental data, from which a Redlich–Kister type polynomial was fit, enabling the determination of the partial molar volumes, the excess partial molar volumes, the apparent molar volumes and the excess partial molar volumes at infinite dilution. The $${\text{V}}_{\text{m}}^{\text{E}}$$ values were also used to test the applicability of the Extended Real Associated Solution Model (ERAS Model). The results for the studied systems suggest that structural effects and chemical interactions must predominate over other possible effects. The magnitude of $${\text{V}}_{\text{m}}^{\text{E}}$$ for the studies systems led to the following order: n-butylamine > propylamine > s-butylamine > diethylamine > t-butylamine.

In this work, nanocellulose particles were obtained from eucalyptus fibers by high-pressure homogenization (CNF) and by high-intensity ultrasound (SCNF). The nanocellulose was applied as a solid emulsifier for soybean oil in water (O/W) emulsions. The adding of 0.25 - 1 wt.% of both CNF and SCNF produced stable O/W emulsions without conventional surfactants. SCNF emulsions showed the highest stability and displayed the narrowest size distribution. Zeta potential values (-40 to -70 mV) indicated an electrical barrier to the droplet coalescence. The rheological behavior of O/W emulsions stabilized with CNF and SCNF was described by the Herschel-Buckley model. O/W emulsions produced with nanocellulose particles behave as shear thinning fluid, and their behavior index ranged from 0.33 to 0.68. Both CNF and SCNF emulsions displayed maximum yield stress at a particle concentration of 0.5wt.% and 0.75wt.%, respectively. Besides, the prepared O/W emulsions using 0.5 to 1.00 wt.% CNF or SCNF did not showed phase separation until 30 days of rest. The data point out to the feasibility of using nanocellulose as a natural emulsifier, which can replace conventional surfactants.

Como parte da comunidade que faz uso da biblioteca pública, os estudantes procuram esse equipamento para responder às suas demandas educacionais, dentre elas, a pesquisa escolar. Diante disso, o objetivo geral desse estudo foi investigar as tipologias de fontes de informação para pesquisa escolar na área de Ciências Biológicas disponíveis no acervo de uma biblioteca pública. Como objetivos específicos elencou-se: identificar os materiais bibliográficos sobre ciências disponíveis no acervo da biblioteca pública; analisar a pertinência e qualidade dos materiais encontrados; categorizar as fontes de informação identificadas. Como metodologia, optou-se pela análise exploratória das fontes de informação disponíveis no acervo da Biblioteca Pública Municipal Professor Francisco Tibúrcio de Oliveira, localizada em Santa Luzia, município da região metropolitana de Belo Horizonte. Dessa forma, foi realizada uma visita técnica à instituição, de maneira que os pesquisadores puderam avaliar os materiais bibliográficos. O acervo encontrado foi categorizado em quatro tipologias distintas: livros teóricos, livros paradidáticos, obras de referência e livros didáticos. A análise dos materiais informacionais acusa uma escassez de fontes de informação que possam embasar adequadamente uma pesquisa escolar. Apesar de tais críticas serem necessárias para evidenciar a falta de investimento na biblioteca pública por parte do município, ressalta-se a pertinência da instituição para a comunidade como ambiente de aprendizagem não formal.

The Fischer–Tropsch (FT) synthesis has been investigated over decades as an alternative route to obtain synthetic fuels from synthesis gas. FT is a high-performance synthesis based on metallic catalysis, mainly using ruthenium, cobalt and iron catalysts, which converts syngas in hydrocarbons and chemical precursors. This work presents a review on the aspects of the syngas production from biomass gasification and its subsequent conversion into fuels through the Fischer-Tropsch synthesis. The usage of biomass, including lignocellulosic residues, as a raw material in the gasification process. Biosyngas is highlighted as a synthetic fuel source to replace nonrenewable, conventional fossil fuels. Lignocellulosic material must be considered a low-cost feedstock to the liquid biofuel production on a large scale. Studies on syngas cleaning to attain the purity required by the FT process is revised. Recent understanding of reaction kinetics and thermodynamics has contributed to increasing the FT performance and economic viability. This paper includes also the debate on main catalysts, industrial process requirements, and chemical reaction kinetics and mechanisms of Fischer–Tropsch synthesis.

The management of tire residues is still a challenge for the industry and governments due to the great volume occupied by the tires and the difficulty of recycling associated with the intricate structure. Thermal degradation is a promisor via to avoid the improper disposal of scrap tires. The waste tire conversion into chemicals by means of pyrolysis yields high added-value products that can be used as reaction precursors and fuels. Tire-derived pyrolysis oil can also be mixed with conventional fossil fuels, producing blends with improved fuel properties and reduced cost. This survey describes the tire compound and the feasibility to convert scrap tire into chemical components as an alternative recycling method, focusing on the tire-derived oil. Pyrolysis is discussed as a method to the tire recovery and reuse, preventing environmental damages and contributing to the sustainable cyclic process. The liquid fraction derived from tire pyrolysis is a complex mixture containing valuable compounds, such as alkyl and alkenyl hydrocarbons, polycyclic aromatics, and terpenes. The assessment of the main properties of tire-derived fuels for industrial and automotive applications are highlighted.

Pyrolysis has been identified as a possible process for producing alternative fuels from thermal degradation of residue materials. In this work, a steam distillation process was applied to extract a light fuel fraction from tire pyrolysis oil. The light fuel fraction (LFF) was a light yellow, translucent liquid with a specific gravity of 0.76 g·cm−3 and dynamic viscosity of 0.4 mPa.s at 20 °C. LFF was mainly composed of volatile organic components of the tire pyrolysis oil. GC-MS analysis shows the light fraction composed mostly of benzene-substituted compounds (62.06%), mainly ethylbenzenes (14.84%) and methylbenzenes (13.02%) derivatives. Saturates were mainly branched alkanes containing eight carbon atoms (21.94%) and cycloalkanes in minor amount (1.35%). Olefins were essentially alkyl-branched cyclohexenes (14.66%), highlighting limonene (8.2%). The standard mid-infrared spectroscopy revealed the light fuel fraction resembles very closely the petroleum-derived gasoline. In addition, typical distillation properties (such as T50, T90, and driveability index) and octane number (Motor Octane Number and Research Octane Number) for the light fuel fraction matched to the gasoline properties. The results point out to the feasibility to replace conventional gasoline by the light fraction obtained from tire-derived oil by means of steam distillation.

The pyrolysis of waste tire has been proposed as an alternative route to its recycling producing residual oils that can be used as fuels. In this work, a physicochemical process to obtain carbonbased dots (CBD) from carbon black (CBL) derivatives of tires is described. For this, the CBL was treated with different acids to produce CBL1 and CBL2 particles suspension. The pH of the suspension was adjusted to 5.6 to precipitate remaining impurities. Afterwards, the supernatant was ultra-centrifuged and the yellow pale solid, the purified CBD obtained by roto evaporation, was characterized by ultraviolet-visible spectrophotometer (UV-Vis), photoluminescence (PL) at 320-380 nm, high-resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared microscopy (µFTIR), and X-ray photoelectron spectroscopy (XPS). This material showed the typical excitation wavelength dependent emission and a PL quantum yield of 19.29% and was constituted by a well-defined spherical shaped and single sheets of “graphene quantum dots” with undefined shape, with potential applications in optoelectronic and fluorescence imaging devices. 31 11 2224 2231

This work presents a study on the interfacial activity of amoxicillin in aqueous systems containing polyethylene glycol (PEG). The results showed that aqueous systems containing different amounts of PEG and amoxicillin reach promptly the chemical equilibrium, displaying a small variation in surface tension over the time. However, the PEG concentration increasing causes a surface tension reduction, which indicates increasing the surface-active component amount on the interface. It was not identified the occurrence of critical micelle concentration for the amoxicillin within the concentration range of this study. Data must be useful for design and operation of processes involving the amoxicillin extraction in two phase aqueous systems containing polyethylene glycol.

Crude oil asphaltenes represent a solubility fraction of petroleum that includes the most polar and most interface-active compounds. Asphaltenes have been involved in solid deposition phenomena in oilfield operations and have produced impractical conditions for oil flow in pipelines and reservoir porous rock. In addition, asphaltenes contribute to the formation of both oil-in-water and water-in-oil emulsions. Therefore, the properties of asphaltene interfacial films are crucial to defining the stabilization or breaking of crude oil emulsions. In this work, the results are presented as a contribution to understanding the elasticity and phase behavior of asphaltene liquid films with changes in subphase pH and temperature. n-Pentane-insoluble asphaltenes (C5I) were extracted from a light crude oil and deposited at the air–water interface from a dichloromethane spreading solution to form two-dimensional monolayers. The C5I films were evaluated using a Langmuir trough under compression at a constant rate. Surf...

Oil-in-water emulsions have been proposed as an emergent technology to transport viscous heavy crude oils. In this work, pipeline flow properties of heavy oil–in–water emulsions and their feasibility to reduce the elevated pressure drop related to the viscous oil flow in pipelines are assessed. Rheological behavior and frictional energy loss were evaluated in a horizontal pipeline device in laminar flow. The experimental set-up consisted of a pilot-scale apparatus fitted with a ¾ in ID pipe. The flow behavior description for emulsions was obtained from flow rate and differential pressure measurements. Under pumping, emulsion apparent viscosity was found to be approximately 100 times lower than the heavy oil viscosity and the pressure drop achieved in the emulsion flow was 20 times lower than that for the flow of pure oil. Results also showed good correlations between the experimental data and the expected value of the Fanning frictional factor for disperse phase concentrations above 50 vol.%. In addition, a correlation between pumping power (related to pressure drop) and flow rate showed that significant pumping energy savings can be achieved and crude oil transportation can be enhanced using an optimal combination of internal oil content and flow rate. Overall, these results indicate that in-line emulsification is a feasible and viable method to move heavy and viscous crude oil in pipes.

Crude oil amphiphilics have been extensively investigated concerning their colloidal properties related to oilfield operation problems. The interfacial structure and elasticity of oil amphiphilic films built on fluid-fluid interfaces have a powerful effect on the stability and rheology of petroleum emulsions and foams. This work presents a description of interfacial films of amphiphilics extracted from petroleum at water-air interfaces using a Langmuir trough. The investigation evaluates surface pressure - area compression isotherms to describe properly the phase behavior of monolayers formed by SARA fractions on isothermal compression at different subphase pH. The SARA films displayed two distinct phase-transitions in different specific areas, according to the pH of the subphase. At pH 2, the surface pressure follows the order: asphaltene > aromatic > resin > saturate, for specific areas higher than 0.04 m2/mg. At neutral and basic pH, the previous order was changed to asphaltene > resin > aromatic > saturate. The surface pressure for asphaltene films was always higher than the surface pressure for other SARA fractions, which is in agreement with the higher surface activity of crude oil asphaltenes. The occurrence of the first phase transition of asphaltene films varies in the range 0.14–0.19 m2/mg with a maxima surface pressure (πmax) of 37.14 mN/m, whereas the second phase transition was held on range 0.069–0.099 m2/mg with a πmax = 55.23 mN/m. The modulus of elasticity (E) of asphaltene compressed-liquid films was found 65–80 mN/m (expect at pH 4, where E~40 mN/m), which is related to the most compressible films. On the other hand, maltene films of SARA fractions showed almost always modulus of elasticity lower than 20 mN/m for both expanded-liquid and compressed-liquid films. The description of the interfacial film nature must be a useful tool to forecast the film stability in the disperse systems as foams and emulsions according to the SARA composition.

Pyrolysis of scrap tires has been pointed out as an alternative to the incorrect disposal of tire wastes. Pyrolysis processes can produce tire-derived oils that may be used as fuel or added to conventional fuels, producing fuel blends with improved properties and reduced cost. The pyrolysis process can contribute to remove tire residues of inadequate sites and it can be a sustainable process to produce alternative fuels. In this work, the properties of blends between petroleum diesel and pyrolytic oil obtained from the thermal degradation of tire waste were investigated. The liquid obtained from the tire waste pyrolysis was black oil, possessing a distinctive, unpleasant and strong odor. The compositional analysis of pyrolytic oil describes the liquid as a complex mixture, composed mainly of aromatic compounds and olefins. The oil specific gravity was 0.93 g cm −3 , while gasoline and diesel showed 0.74 and 0.84 g cm −3 , respectively. The Research Octane Number (RON) for the pyrolytic oil was found to be similar to the RON for Premium gasoline (higher than 100). Its Motor Octane Number (MON) was found to be slightly lower than the MON for gasoline and very higher than those to diesel fuel. The pyrolytic oil showed also higher detonation resistance in relation to the conventional fuels investigated. The oil has the High Heat Value (HHV) in-between than that for gasoline and diesel fuel, achieving 42 kJ g −1 . The tire pyrolysis oil was miscible with diesel in the entire concentration range. Pyrolysis oil/diesel blends showed properties that make them able to be applied as fuel. However, blend properties highlight the complexity of the chemical interactions between the fuels, which need consideration before their applications.

This study introduces a new framework to quantify the wettability of powdered carbonate rock from existing correlations between zeta potential and contact angle. The new framework has the potential to be faster and cheaper than conventional approaches and could increase confidence in surface wetting quantification, since the results are insensitive to the inherent heterogeneity of rock surfaces. The obtained results from experiments were used to develop a set of equations for determining the carbonate rock contact angle from streaming potential data. The equations were validated for the evaluation of changes in the wettability of carbonate rock using different stearic acid oily solutions. The contact angles calculated from the proposed equations were then compared with measured values on the calcite surface. The results show that the proposed framework was able to quantify the wettability of carbonate rock with an acceptable range of error of about 4%–14%.

Crude oil asphaltenes contain a wide series of chemical species, which includes the most polar compounds and interfacially active agents from the petroleum. Asphaltenes have been considered to be implicated in foam and emulsion formation during the petroleum recovery and production process. In this work, the interfacial activity of organic solutions containing asphaltene and n-alcohols was investigated. Asphaltene extraction from a 28°API crude oil produced 2.5 wt % of n-pentane precipitated asphaltene (C5I). Dynamic surface and interfacial tensions of asphaltene solutions were assessed by the pendant drop method. Asphaltene films were evaluated at the air-water interface using a Langmuir trough. Results were expressed by means of the interfacial tension time-dependence. Interfacial tension measurements showed alcohols reduce the toluene/water interfacial tension of asphaltene solutions. The interfacial tension was reduced from 23 mN/m to 15.5 mN/m for a 2 g/L solution of asphaltene plus n-butanol. Higher asphaltene concentrations did not affect the toluene/air surface tension. The effects of n-alcohols on the asphaltene surface activity was dependent on the asphaltene aggregation state. n-Alcohols modify the asphaltene film elasticity and the film phase behavior.

This work presents an experimental study on the thermal and kinetic parameters of the oxidation reaction of heavy crude oils to support the in-situ combustion oil recovery technique. An accelerated rate calorimeter was used to investigate the thermal behavior of two Brazilian heavy oils in an open system under constant pressure and continuous heating to 550 °C. The goal was to identify and characterize several oxidation regions and to obtain the activation energy and reaction order. The temperature–time curves showed three clearly distinct regions. During the heating, autoignition was found to have started at 180–220 °C. Then, the reaction curves exhibit a strong exothermic behavior up to 250–350 °C, which represents the low-temperature oxidation. Asphaltenes were found to play a crucial role in the kinetic behavior of the crude oils. The results show that oxygen-addition reactions are dominant from 200 to 300 °C and that bond-scission reactions are dominant above 350 °C. Although the presence of sand and...

This work reports an experimental investigation of the oil segregation effect during the rheological evaluation of concentrated oil-in-water (O/W) emulsions. The results demonstrated that alkyl alcohols can significantly affect the rheological behavior of O/W emulsions. The addition of n-octanol and n-decanol to the emulsifying agent formulation produces a critical shear rate, promotes a sharp break in the flow curves and leads to a sharp viscosity drop, which was attributed to wall depletion. This phenomenon is related to the displacement of the dispersed phase away from the solid-boundary, which generates a low-viscosity oil-depleted layer that acts as a lubricating layer. The incidence of slippage depends on the alkyl-chain length and the concentration of the alcohol. The lubrication layer will promote energy savings during emulsified oil pumping and result in significant economic benefits to the petroleum industry.

Unconventional oils - mainly heavy oils, extra heavy oils and bitumens - represent a significant share of the total oil world reserves. Oil companies have expressed interest in unconventional oil as alternative resources for the energy supply. These resources are composed usually of viscous oils and, for this reason, their use requires additional efforts to guarantee the viability of the oil recovery from the reservoir and its subsequent transportation to production wells and to ports and refineries. This review describes the main properties of high-viscosity crude oils, as well as compares traditional and emergent methods for their recovery and transportation. The main characteristics of viscous oils are discussed to highlight the oil properties that affect their flowability in the processes of recovery and pipeline transportation. Chemical composition is the starting point for the oil characterization and it has major impact on other properties, including key properties for their dynamics, such as density and viscosity. Next, enhanced oil recovery (EOR) methods are presented, followed by a discussion about pipeline and transportation methods. In addition, the main challenges to achieve viable recovery and transportation of unconventional oils are compared for the different alternatives proposed. The work is especially focused on the heavy oils, while other hydrocarbon solid sources, such as oil sands and shale oil, are outside of the scope of this review.

Injection of carbon dioxide into carbonate oil reservoirs is expected to promote chemical dissolution of the rock and alter its petrophysical properties. This work reports an experimental investigation on porosity and permeability alterations of carbonate samples due to the acid action of the carbonated water produced by means of solubilization of carbon dioxide in an aqueous solution. Travertine marble rocks with properties similar to Brazilian pre-salt reservoir rock were used in the tests at 9000 psi and 65 °C. Dissolution was carried out in high-pressure vessels during a total period of 240 h. Reaction was stopped at intermediate time intervals to evaluate porosity, permeability and mass loss of the samples. Results showed that the dissolution reaction between the travertine and carbonated water presents a slow kinetic, leading to a small loss of 0.2 g of sample after 240 h of reaction. However, the minor mass loss impacts strongly on the porosity and permeability of the rock. Data show that a variation of 1 wt.% on the sample mass caused by dissolution produces a change of 50% on the sample porosity and of 180% on the sample permeability. The dissolution rate is greatly faster if carbonated water is replaced by HCl aqueous solution and depends on the acid solution concentration. In addition, results lead to an exponential model that allows forecasting the mass loss as a function of time. Knowledge on the dissolution rate of carbonate samples by carbon dioxide solutions is required in EOR and CO2 storage projects to estimate the changes on the flow properties of the porous formation and the damages that can be impinged to the rock.

Accelerating rate calorimetry has been used to study the thermal behavior of the combustion reactions that occur during the in situ combustion process and to estimate key parameters for the numerical simulation studies. This work reports the results from a study on the combustion reactions of heavy oil based on experimental tests using an accelerating rate calorimeter. The temperature settings covered a ramped ranging from 50 to 550 °C. The pressure was kept constant at 20 and 40 bar, and the air flow rates were tested for values of 90 and 120 mL min−1. An experimental design was built to provide the effects of pressure, air inflow, and oil mass on the main kinetic parameters. Activation energy was 0.6–64 × 103 kJ mol−1, with higher variation in Test-1. LTO region was represented by just one reaction and its activation energy was ~102 kJ mol−1 across every tests. Process variables were found to affect the exothermal temperature interval, the activation energy, and the order of reaction. Effects of variables on the kinetic parameters were found to be dependent on specific reaction temperature range, being more pronounced in the range of higher temperatures.

This work describes the formulation and evaluation of concentrated, heavy oil-in-water emulsions stabilized by mixtures of ethoxylated surfactants and normal alcohols. The rheology, stability and droplet size of these emulsions were investigated as functions of the emulsification process parameters. The parameters investigated for this study include emulsifier agent composition, presence of additives, pH and salinity of the continuous aqueous phase, emulsification temperature, oil content and emulsion aging. The produced emulsions had viscosities ranging from 30 to 150 mPa s and represent a 30-fold reduction of the crude oil viscosity. Sauter mean diameters of the droplets ranged from 10 to 50 μm. The emulsions were produced by mixing the oil with an aqueous solution containing medium normal-chain alcohols and small quantities of a mixture of ethoxylated nonylphenol and ethoxylated amine surfactants. The presence of these alcohols led to a sharp decrease in the droplet size of the emulsion. This size decrease had a direct impact on the emulsions’ stability and apparent viscosity. The rheological parameters of the aged emulsions were also essentially constant over a 42-day period.

Organogel formation during paraffin crystallization is one of the causes of oilfield problems. We investigated the formation of n-alkane organogels having C10 as liquid phase and n-octacosane (C28) and n-tetracontane (C40) as solid gelators. It was seen that C10/C28 and C10/C40 form organogels with onset gelation temperatures of 33°C and 48°C respectively, while C10/C28/C40, gelify at 52°C. Replacement of C28 by n-heneicosane (C21) reduced the crystallization rate of C40. This result indicates that the onset temperatures and crystallization rates of organogels with gelators in the range of C28 to C40 could be modulated through the introduction of shorter chain n-alkanes.

The technology of oil flow in pipelines assisted by its confinement within an annular aqueous section, known as core-flow, has emerged as a viable alternative for the transportation of heavy crude oils. The lubricating effect of the aqueous film leads to reduced equivalent viscosities and, hence, low energy consumption. One of the possible problems associated with this technique is the gradual accumulation of oil on the inner pipeline surfaces, requiring the use of cleaning procedures. This work is aimed at investigating the roles of the oil polar components on the wetting of such surfaces by crude oils through contact angle measurements in systems containing heavy oil/aqueous phase/metallic surfaces. Asphaltenes and naphthenic acids were removed from the crude oil, respectively, by flocculation with alkanes and by washing with alkaline solution. As model metallic surfaces, commercial and galvanized steel were used; and the studied aqueous phases comprised pure water, 1% sodium chloride and sodium meta-silicate solutions. Static contact angles were determined via the placement of an oil droplet under the metallic surface in the presence of an aqueous phase. These measurements revealed small influence of the nature of the metallic surfaces on the observed wettability. Significant effects, however, were observed depending on the presence of asphaltenes and naphthenic acids, whose removal reduced the contact angles from an oil-wet behavior (angles above 145°) to a water-wet situation, with angles smaller than 45° and 80°, respectively. Experiments carried out with aqueous phases containing 1% sodium meta-silicate and sodium chloride revealed contact angles smaller than 60° in most cases, confirming their suitability for the prevention of oil deposition onto these surfaces. Moreover, this study confirms that measurements of static contact angles are useful for screening of formulations and surfaces used in oil transportation prior to flow tests.

Abstract Molecular diffusion is the process describing the natural mixture of miscible fluids, whose main modeling parameter is the molecular diffusion coefficient. This work aims to evaluate the molecular diffusion coefficient for CO2-light oil systems under different experimental conditions of pressure. Experimental measurements are based on both pressure decay and computed tomography (CT) scan methods. The oil studied is light oil from Brazilian subsalt oil reservoirs. Tests were carried on a specially constructed vertical high pressure cell, from 2.76 MPa up to 28.96 MPa and at 293.15 K. The swelling effect was also evaluated during the diffusion process considering the height variation of the oil column inside the cell. Molecular diffusion is particularly important for miscible gas flooding processes, as diffusion is a key mechanism controlling the miscibility between oil and gas. The diffusion coefficient determines the rate of mass transfer during the diffusive process that will result in a miscible system. The diffusivity of solvents into light oil in porous media has become of great significance in petroleum engineering, since CO2 injection has been proposed more and more as the enhanced oil recovery method to be applied in the reserves of conventional oils. Currently, the topic of CO2 diffusion in light oils is scarcely described in the public literature, while diffusion in CO2-heavy oils systems has attracted some attention. Although both diffusion process and swelling effect have a common ground, many differences must be taken into consideration to truly model the mass transfer phenomenon. Diffusion coefficients were obtained using the CT method and the pressure decay technique throughout Etminan et al. (2013) interface resistance model. Both methods have significative discrepancies in coefficients values. The diffusivities obtained from pressure decay were more consistent with published data. Therefore pressure drop technique seems more robust even for CO2-light oil mixture, while CT technique needs further improvements. Furthermore, as Etminan et al. (2013) model is applicable only for VLE conditions, an improved model will be required for additional LLE situations. Introduction Molecular diffusion is the process by which matter is transported from one place in a system to another as a result of random molecular motions (Crank, 1958). It is well established that the diffusion coefficient measured in a two-component system depends on the presence or absence of a chemical concentration gradient. In addition, it also has been explained that there is an asymmetry of molecule movement frequency when a gradient is detected. This asymmetry is due to particle thermodynamics, thus mass flow occurs by diffusion when there is a pressure gradient at that level (Prager, 1953). In petroleum engineering, molecular diffusion is a key mechanism in solvent-solute process mainly applied for the improvement of petroleum recovery. In the case of gas-based heavy oil recovery, it has been recognized that the molecular diffusion and convective-dispersion are the two important mass transfer processes. The former has a significant role during the soaking time, while the latter is predominant during the time of solvent injection (Tharanivasan, 2006). The efficiency of the recovery process is highly affected by the rate of dissolution of the injected gas into the target oil, which is controlled by molecular diffusion. So are the resulting changes in the oil properties. Molecular diffusion, whose main characteristic parameter is the molecular diffusion coefficient, is the process describing the natural mixture of miscible fluids. In the recovery processes the diffusion promotes mixing between the injected gas and the oil, prevents viscous fingering, retards gas breakthrough and therefore improves the sweep efficiency for enhancing oil recovery (Ping Guo, 2009).

Abstract The understanding of single and multiphase flow behavior in porous media has been improved with the development of in situ saturation measurement techniques such as X-ray Computed Tomography (CT), mainly in specialized core analysis. On the other hand, effective experimental designs are necessary to advance knowledge on operations of Water Alternating Gas (WAG) and Carbon Capture and Storage (CCS) projects. The present study addresses the determination of petrophysical properties concerning fluid storage and displacement in carbonates by using CT images taken during core flooding runs. Eight displacement experiments were carried out in long core to analyze N2 and CO2 flooding under reservoir conditions (from 700 to 7000 psi) at temperatures of 22°C and 65°C. A carbonate core sample of 5 cm diameter by 76 cm long with porosity of 15% from a carbonate outcrop analogous to Brazilian pre-salt reservoir rocks was used in the displacement tests. The mixing of CO2 and brine was a key experimental procedure to evaluate the CO2 trapping. The parameters of porosity, permeability, distribution of initial non-wetting phase, irreducible brine saturation, trapped non-wetting phase saturation, displacement effectiveness and the effect of saturation history were investigated during drainage-imbibition cycles similar to those in the WAG process. Values for Land trapping coefficients were evaluated from on-line X-ray CT scan images. The trapped non-wetting phase saturation ranged from 8 to 16 percent for both N2 and CO2 floods. The results reveal that trapped saturations are higher for higher pressures and higher temperatures. Cross-section images show the enlargement of pore spaces induced by brine-CO2 flooding with a consequent increase of the trapping capacity. Porosity and permeability changed after a CO2 injection, along with the observed formation of short wormholes. In addition, some degree of dissolution of the rock was verified and solid particles of carbonate salts were collected at the outlet of CO2-brine runs. The results obtained emphasize the importance of using high-resolution saturation imaging to provide the main parameters for the experimental evaluation of CO2-WAG processes in carbonates. Introduction Carbon dioxide (CO2) flooding has been considered as one of the most important processes for enhancing oil recovery (EOR) from carbonate reservoirs since the 1980's [1]. Its use, though, is most of the time limited by the availability of an economic source. In the Brazilian pre-salt reservoirs, e.g., Tupi field, the solution gas contains a high proportion of CO2 [2]. The re-injection of the produced CO2 in this case represents the solution of two problems at once. It solves the discard problem, which is of growing environmental concern, at the same time it provides the resource for improving the difficult oil recovery. Both EOR and environmental processes demand new studies covering the application of WAG injection and the safety of geological storage of CO2. The alternating injection of water and gas was conceived in order to compensate the counter tendencies of gas rising upward and water falling downward within the reservoir by ‘breaking-up’ the continuous slug of gas into smaller slugs by alternating water banks [3]. On the other hand, injecting water with miscible gas reduces the instability of the gas/oil displacement, improving the overall sweep efficiency.

Surface tension knowledge of surfactants aqueous solutions is important during amphiphilic molecule manufacturing and new product development, as feedback information to handle synthesis parameters to target performance. Drop counting method is an interesting simplification of drop weight method for surface tension measurements. A simple laboratory measurement device, with capability for temperature control, was assembled to allow investigation of ethoxylated surfactants. The implementation of the method was preceded by a detailed investigation of two factors that may affect the measured surface tension: drop formation velocity and surfactant ethoxylation degree. The limitations of the method are discussed on this basis.

Orientadores: Watson Loh, Antonio Carlos Bannwart Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica Resumo: Emulsões óleo em água (o/a) têm sido propostas como alternativa aos métodos convencionais para redução dos problemas associados ao escoamento, causados pela alta viscosidade destes óleos. Nestas emulsões, o óleo se encontra disperso na fase aquosa sob a forma de gotículas e pode ser bombeado sem necessariamente entrar em contato com as paredes do duto, reduzindo os efeitos viscosos e ampliando a capacidade de transferência. Neste trabalho, realizou-se um estudo experimental sobre a aplicação de emulsões de óleo em água (o/a) no transporte de óleos pesados brasileiros. Emulsões contendo 50-70% de óleo disperso foram preparadas sob diferentes parâmetros da formulação fisico-química, permitindo adequação de suas propriedades às exigência da aplicação. Eficaz protocolo de preparação produziu gotas com diâmetro médio de Sauter D3,2da ordem de 10-50 micrômetros e com distribuição de diâmetros obedecendo a uma distribuição lognormal. A reologia e a estabilidade das emulsões foram dependentes do diâmetro médio de gota e da distribuição de tamanhos. Emulsões mostraram alta estabilidade sob condições severas de avaliação. A emulsificação reduziu a viscosidade de 1.000 cP do óleo original para 30-150 cP da emulsão o/a, produzindo decréscimo de cerca de 30 vezes na viscosidade do óleo. As emulsões mostraram comportamento pseudoplástico descrito pela lei de potência (modelo de Ostwald-de Waele), apresentando influência do envelhecimento. O óleo cru pode.ser recuperado pela quebra da emulsão utilizando desemulsificantes comerciais, produzindo BS&W de cerca de 5%. Um sistema' de fluxo experimental em escala piloto com comprimento reto de teste de 3 m foi constiuído com tubulação de aço API com % in d.i. para ensaios de escoamento das emulsões. A viscosidade foi calculada a partir de dados de queda de pressão. A viscosidade de emulsões óleo em água com 50%, 60% e 70% de óleo disperso foi adequadamente prevista pela lei de potência, mostrando valores até 100 vezes menor que a viscosidade do óleo em escoamento a 500 S.I. As perdas de carga observadas durante o escoamento de emulsões são até 20 vezes inferior às do óleo em fluxo monofásico, o que também se verifica através da estimativa da potência requerida de bombeio. As emulsões óleo em água produzidas neste estudo mostram a viabilidade técnica da aplicação de emulsões óleo em água para o escoamento de óleos pesados, incluindo operações de elevação e transporte em oleodutos convencionais. Abstract: Use of oil-in-water (o/w) emulsions for transportation of heavy crude oils has been proposed as altemative means of reducing problems associated with difficulties in transport of these fluids for their high viscosity, with some advantages over the currently used methodologies. In these emulsions, oil is dispersed as stabilized droplets allowing its transportation with low pressure drops and avoiding oil contact with the pipeline walls. This study involved the experimental evaluation of o/w emulsions for the transportation of Brazilian crude oils. Emulsions containing 50-70% oi! were prepared with different formulations. An efficient methodology of preparation produced emulsions with droplet diameters (Sauter diameter, D3,2) in the range of 10-50 micrometers and a log-normal size distribution. Rheology and stability of these emulsions depend on their average diameters and size distributions. These emulsions displayed high stability under severe conditions (centrifugation). Using this approach, oil viscosity of around 1 000 cP was reduced to 30-150 cP. These emulsions display a pseudoplastic rheological behavior following the power law described by the Ostwald-de Waele model, which changed with their aging. Crude oil could be recovered after emulsification using commercial additives, producing BS&W values of 5 %, which could be further reduced with more severe treatments (down to 0.5 %). An experimental set-up was built for flow assays in pilot scale with 3 m length for measurements made of API steel with :;4 in (i.d.). Viscosity was obtained from drop pressure data. The power law adequately adjusted emulsions containing several oil contents. Emulsions viscosity was found to. be up to 100 times lower tIutn the oil viscosityat 500 S-I and drop pressure in the emulsion flow was 20 times lower than q,il monophasic flow. In summary, all of these measurements confirm the viability of these emulsions for use in transportation of heavy crude oils, induding their lift and transportation in conventional pipelines. Doutorado Engenharia de Processos Doutor em Engenharia Química