Heavy Crude Oil Samples Research Articles

Synthesis of a non-polymeric surfactant from naturally occurring vegetable acid and its use as a viscosity modifier and asphaltene dispersant for heavy oil

The extraction and transportation of heavy oil, which accounts for a significant portion of the world's energy sources, often requires the use of various methods, including the use of chemicals. Surfactants have proven effective in this regard. Therefore, the present study focuses on the synthesis of a non-polymeric surfactant derived from naturally occurring vegetable acid. The synthesized surfactant is subsequently characterized using several analytical techniques, namely FTIR (Fourier Transform Infrared Spectroscopy), NMR (Nuclear Magnetic Resonance), TGA (Thermogravimetric Analysis), and elemental analysis. The surfactant demonstrated promising properties as a viscosity modifier and asphaltene dispersant for heavy crude oil samples. The results obtained at a concentration of 600 ppm were particularly favourable, with minimal improvements observed beyond this concentration. The analysis of asphaltene samples further supported the surfactant's effectiveness through hydrogen bonding and π-π interaction. UV–visible spectroscopy and relative viscosity measurements provided additional evidence of the surfactant's ability to disperse asphaltenes effectively.

Aquathermolysis of Heavy Crude Oil: Comparison Study of the Performance of Ni(CH3COO)2 and Zn(CH3COO)2 Water-Soluble Catalysts

Aquathermolysis is one of the crucial processes being considered to successfully upgrade and irreversibly reduce the high viscosity of heavy crude oil during steam enhanced oil recovery technologies. The aquathermolysis of heavy oil can be promoted by transition metal-based catalysts. In this study, the catalytic performance of two water-soluble catalysts Ni(CH3COO)2 and Zn(CH3COO)2 on the aquathermolytic upgrading of heavy oil at 300 °C for 24 h was investigated in a high pressure–high temperature (HP-HT) batch reactor. The comparison study showed that nickel acetate is more effective than zinc acetate in terms of viscosity reduction at 20 °C (58% versus 48%). The viscosity alteration can be mainly explained by the changes in the group composition, where the content of resins and asphaltenes in the upgraded heavy crude oil sample in the presence of nickel catalyst was reduced by 44% and 13%, respectively. Moreover, the nickel acetate-assisted aquathermolysis of heavy oil contributed to the increase in the yield of gasoline and diesel oil fractions by 33% and 29%, respectively. The activity of the compared metal acetates in hydrogenation of the crude oil was judged by the results of the atomic H/C ratio. The atomic H/C ratio of crude oil upgraded in the presence of Ni(CH3COO)2 was significantly increased from 1.52 to 2.02. In addition, the catalyst contributed to the desulfurization of crude oil, reducing the content of sulfur in crude oil from 5.55 wt% to 4.51 wt% The destructive hydrogenation of resins and asphaltenes was supported by the results of gas chromatography-mass spectroscopy (GC-MS) and Fourier-transform infrared (FT-IR) spectroscopy analysis methods. The obtained experimental results showed that using water-soluble catalysts is effective in promoting the aquathermolytic reactions of heavy oil and has a great potential for industrial-scale applications.

Chemical Viscosity Reduction of Heavy Oil by Multi-Frequency Ultrasonic Waves with the Main Harmonics of 20–60 kHz

Ultrasound technologies are well-known for their ability to intensify the heat and mass transfer processes. Hence, ultrasonic treatment processes are widely applied for the separation of oil–water emulsions, optimization of oil pumping processes, cleaning the bottomhole zone, etc. However, the main phenomenon under the positive influence of ultrasonic waves on such processes is the cavitation bubbles implosion on the water–oil boundary. It is well-known that ultrasound energy contributes to the reversible viscosity reduction in heavy oil systems. However, it is possible to exhibit chemical destruction of the weakest carbon–heteroatom bonds in the structure of the asphaltenes. This study investigates the influences of controllable ultrasound waves with frequency ranges of 20–60 kHz under the exposure time of 60 s on the rheology of a heavy crude oil sample produced from the Ashalcha reservoir (Tatarstan Republic, Russia). The specific feature of this study is the application of multi-frequency ultrasonic exposure with a wide spectrum of side harmonics with the frequency up to 400 kHz. The results of the Saturates, Aromatics, Resins and Asphaltenes (SARA) analysis method support the chemical consequences of ultrasonication of crude oil. The content of resins under the irradiation of ultrasound waves altered from 32.5 wt.% to 29.4 wt.%, while the number of aromatics hydrocarbons raised from 24.3 wt.% to 34.1 wt.%. The Gas Chromatography—Mass Spectroscopy (GC-MS) analytical analysis method was applied to qualitatively compare the composition of saturated and aromatics fractions between the initial and upgraded heavy crude oil in order to show the chemical destruction of asphaltene bonds after the ultrasonic treatment. It was demonstrated that ultrasound waves allowed chemical conversion of asphaltene fragments that led to irreversible viscosity reduction. The viscosity of the heavy oil sample under the favorable ultrasonic irradiation conditions reduced from 661.2 mPa·s to 178.8 mPa·s. This advantage can be used to develop enhanced oil recovery methods and partial upgrading processes in downstream conditions.

Machine learning estimation of crude oil viscosity as function of API, temperature, and oil composition: Model optimization and design space.

Measurement of viscosity of crude oil is critical for reservoir simulators. Computational modeling is a useful tool for correlation of crude oil viscosity to reservoir conditions such as pressure, temperature, and fluid compositions. In this work, multiple distinct models are applied to the available dataset to predict heavy-oil viscosity as function of a variety of process parameters and oil properties. The computational techniques utilized in this work are Decision Tree (DT), MLP, and GRNN which were utilized in estimation of heavy crude oil samples collected from middle eastern oil fields. For the estimation of viscosity, the firefly algorithm (FA) was employed to optimize the hyper-parameters of the machine learning models. The RMSE error rates for the final models of DT, MLP, and GRNN are 40.52, 25.08, and 30.83, respectively. Also, the R2-scores are 0.921, 0. 978, and 0.933, respectively. Based on this and other criteria, MLP is chosen as the best model for this study in estimating the values of crude oil viscosity.

The role of reservoir fluids and reservoir rock mineralogy on in-situ combustion kinetics

In-situ combustion (ISC) is a complex process with great potential. This study aims to simplify some of the complications associated with the reaction kinetics of ISC and investigate the impact of reservoir rock composition and crude oil fractions on the reaction kinetics of ISC.Sixty-six reaction kinetics experiments were conducted using Thermogravimetric Analysis/Differential Scanning Calorimetry (TGA/DSC) on two heavy crude oil samples and two types of porous media (clays and carbonates). In these experiments, a 5 °C/min heating rate was used to simulate the low-temperature-oxidation (LTO) region, and a 20 °C/min heating rate was used for the high-temperature-oxidation (HTO) region. The role of crude oil composition on the reaction kinetics of combustion was also investigated through saturates, aromatics, resins, and asphaltenes (SARA) fractionation. The two crude oils were first separated into their SARA fractions, and then the reaction kinetics of individual fractions and their two and three component pseudo-blends were studied.‘To understand the contribution of aquathermolysis reactions, the crude oils and their SARA fractions were mixed with water, and the reaction kinetics tests were repeated in the presence of water. The chemical reactions occurring in the presence and absence of water in crude oil and their fractions were discussed using control experiments conducted on known simple hydrocarbons: n-decane (C10H22), n-decanal (C10H20O), n-decanol (C10H22O), and decanone (C10H20O). Additionally, the reactivity of the mineralogy of the porous media was examined, and both clay and carbonates were tested. All experiments were analytically modeled to obtain reaction kinetics parameters in terms of activation energy (Ea) and heat generation (ΔH).The results show that while emulsified water decreases the effectiveness of the combustion process, the presence of initial water increases it. This is due to the increase in heat generation and decrease in activation energy, which is mainly caused by the interaction between water and aromatics fractions (aquathermolysis reaction) at elevated temperatures. The amount of clay in the reservoir is critical for the success of the ISC process. If the reservoir has a higher clay content than a certain threshold, the combustion performance will be compromised. Resins fractions have a higher tendency to interact with carbonates during ISC in the HTO region.Overall, this study provides simplified analytical approaches based on experimental results to better understand the ISC chemical reaction kinetics for different types of crude oil and reservoir rocks.

Effect of laser irradiation on a heavy crude oil sample: Changes in viscosity and implications for oil recovery and transport

High-viscosity oil has attracted people's attention as unconventional energy. Hence, the viscosity reduction played a significant role in pipeline transportation. In this paper, a 532 nm laser was employed to reduce the viscosity. Both voltage and temperature will change under laser irradiation due to the thermal effect. Moreover, the variation in the voltage and temperature was studied without laser irradiation in order to research the influence of laser irradiation on experimental results with different bias currents. An exponential function was used to fitted waveforms of falling voltage in order to study the effect of laser irradiation on liquid. The relationships among the voltage, temperature, and viscosity were also studied under laser irradiation. Particles in the crude oil absorbed energy from laser, which led to the liquid conductivity change. Due to laser irradiation, the temperature of the liquid will rise, resulting in the viscosity change. Laser technology will provide a distinctive driving force for the viscosity reduction.

Investigations on asphaltene aggregate formation by high-field diffusion NMR and low-field ghost solvent NMR relaxometry

Aggregation of asphaltenes remains a scientific challenge. In the present contribution, at first, transverse magnetization relaxation (T2) data from low-field NMR measurements of the asphaltenes from heavy, medium-heavy, or light crude oil samples were recovered. Following this, diffusion ordered spectroscopy nuclear magnetic resonance (NMR) spectra of these asphaltenes were acquired to obtain average molecular weights (M w) of asphaltene aggregates. Analyzing the relaxation and diffusion behavior of asphaltene aggregates as a function of solution percentage and hence molecular weights are utilized to explain the difference between light, medium-heavy and heavy crude oil asphaltenes in aggregate formation. The main results suggest that light crude oil asphaltenes form a small but significant number of aggregates. In contrast, heavy crude oil asphaltenes demonstrate a more complicated picture at high concentrations with small, medium, and large aggregates. The relaxation behavior of medium-heavy asphaltenes is similar to those of heavy crude oil asphaltenes in diluted solutions and similar to light crude oil asphaltenes in concentrated solutions. Diffusion NMR results showed that the light crude oil asphaltene samples have a relatively smaller aggregate size, higher diffusion coefficient, and hence a smaller molecular weight than the samples extracted from heavy crude oils.

Behavior study of a thermo‐responsive hydrophobically associative water‐soluble terpolymer in laboratory test with heavy crude oil

AbstractIn this work, a thermo‐responsive hydrophobically associative water‐soluble terpolymer was prepared and evaluated as polymer flooding in laboratory tests versus a heavy crude oil from a carbonated reservoir in southern Mexico. Terpolymer of acrylamide, N‐isopropylacrylamide and N,N′‐dihexylacrylamide were synthesized via micellar free radical polymerization. Reaction was carried out at 50°C using sodium dodecyl sulfonate as surfactant and 4‐(4′‐azobis)cyanovaleric acid as initiator. The terpolymer was characterized by nuclear magnetic resonance. Steady shear viscosity of polymer solutions at different concentrations was determined in the presence of NaCl (from 1 to 5 wt%) at different temperatures (from 25 to 120°C). Heavy crude oil sample was characterized and revealed a viscosity of 2. 26 Pa s, 10.21° API with a content of Saturates, Aromatics, Resins, Asphaltenes of 26.4, 38.5, 22.3, and 12.8, respectively. The crude oil recovery of polymer at 2 and 3 wt% revealed a surface tensions of 49.6 and 48.2 mN × m and adsorption capacities of 1.33 and 1.77 wt%. Finally, polymer solutions at 2 and 3 wt% showed a contact angle between 29.6 and 26.5° and a crude oil recovery of 68.3 and 75.3%, respectively.

Optimization and uncertainty quantification of in situ combustion chemical reaction models

Heavy oil, deep, and waterflooded reservoirs contain significant petroleum resources but present many unique challenges for oil recovery. In situ combustion (ISC) is a thermal enhanced oil recovery method that has been proposed for such reservoirs. A persistent challenge in understanding ISC is modeling the underlying chemical reactions. While many different reaction models have been proposed, these models are typically developed on an ad-hoc basis for individual crude oil samples and manually calibrated to experimental data. While some work exists on applying optimization-based approaches to reaction calibration, existing approaches are not fully-generalized nor do they quantify uncertainty in the estimated parameters. Here we present such an approach for calibrating and quantifying uncertainty in ISC chemical reaction parameters. The workflow presented is generalized to any hydrocarbon pseudocomponent-based reaction model of ISC, provides a framework for quantification of uncertainty in estimated parameters, and is fully automated. Thus, no parameter initialization or manual calibration is needed. We apply this workflow to characterization of a heavy crude oil sample and demonstrate the capability of this workflow to predict ISC oxidation kinetics and upscale to a combustion tube simulation. Overall, this work provides an algorithmic approach to calibrating ISC kinetics that enables quantitative analysis and comparison of oil types, reaction models, and reservoir conditions for ISC.

Upgrade of heavy crude oil via aquathermolysis over several types of catalysts

A solid NaY zeolite catalyst was synthesized from raw materials using a hydrothermal method. The NH4Y and HY forms of the catalyst were then prepared using multistage ion-exchange and calcination processes, respectively. Cobalt and Zinc as transition metals were loaded into the HY structure through impregnation method. The synthesized Zn/HY and Co/HY zeolites along with ZnO and CoO nanoparticles were all used as catalysts for aquathermolysis. The catalysts were characterized using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy-energy-dispersive X-ray spectroscopy, and Brunauer-Emmett-Teller surface area and pore volume analysis. A stainless-steel autoclave operated at 45 bar and 250 °C for 24 h was employed for upgrading heavy crude oil samples extracted from the East Baghdad oilfield using toluene as the hydrogen donor. The reaction products were analyzed by evaluating the changes in their viscosity, API gravity, density, pour point, and flash point. The results indicated that the efficiency of the catalysts decreased as follows: Zn/HY zeolite > Co/HY zeolite > nano CoO > nano ZnO > HY zeolite > in the presence of the hydrogen donor only = in the absence of catalysts or the hydrogen donor. The decrease in the S-content of the products was also evaluated. The results indicated that the efficiency of the catalysts decreased as follows: Co/HY zeolite > Zn/HY zeolite > nano CoO > nano ZnO > HY zeolite > in the presence of the hydrogen donor only > in the absence of catalysts or the hydrogen donor. The S-content of the products obtained over the Co/HY zeolite catalyst decreased the most (by 65.63%). Moreover, the viscosity of the crude oil obtained over the Zn/HY zeolite catalyst decreased the most (by 63.69%).

Superhydrophobic nanohybrid sponges for separation of oil/ water mixtures

The industrial revolution has led to different types of environmental pollution, including frequent leakage of crude oil to marine waters and the contamination of wastewater with immiscible or emulsified oils and organic liquids from various industrial residues. Hence, developing multifunctional materials for oil/water separation is a field of high significance for the remediation of oil-polluted water. Recently, advanced superwetting materials have been employed for oily wastewater treatment. This review summarizes the recent development in fabricating superhydrophobic/superoleophilic nanohybrid polyurethane, melamine, and cellulose sponges for oil/water separation. The use of organic and/or inorganic nanohybrid materials opens the horizon for designing a diverse and wide range of superhydrophobic sponges due to the synergistic effect between the surface roughness and chemical composition. The discussion is organized based on different classes of low surface energy materials including thermoplastics, thermosets, elastomers, fluorinated polymers, conductive polymers, organosilanes, long alkyl chain compounds, and hydrophobic carbon-based materials. Recent examples for the separation of both immiscible and emulsified oil/water mixtures are presented, with a focus on fabrication strategies, separation efficiency, recyclability, mechanical performance, and durability. Currently, most studies did not focus on the mechanical/chemical stability of the fabricated sponges, and hence, future research directions shall address the fabrication of robust and long-term durable superhydrophobic sponges with proper guidelines. Similarly, more research focus is required to design superhydrophobic sponges for the separation of emulsified oil/water mixtures and heavy crude oil samples. Superhydrophobic sponges can be employed for treatment of oily wastewater, emulsion separation, and cleanup of crude oil spills.

The effect of clay minerals on conversion of Yarega heavy oil during catalytic aquathermolysis process

In this study we present the results of physical stimulation of in-situ aquathermolysis process carried out on heavy crude oil sample from Yarega (Russia) oil field in the presence of nickel/iron tallates and clay minerals. The experimental results revealed that clay minerals as the co-catalyst show the best performance at 300 °C in case of nickel tallates, where the viscosity of aquathermolysis products reduces by 4 times in contrast to the initial crude oil. Moreover, the content of saturated fraction isolated from the catalytic aquathermolysis products increased from 36.8 to 50.2 in contrast to the saturated fraction of initial crude oil, while the amount of resins decreased by two times after hydrothermal treatment in the presence of nickel catalyst and clay minerals. Thus, the obtained results justify the involvement of clay minerals to the aquathermolysis process and demonstrate catalytic performance in terms of enhancing group composition and viscosity reduction. Keywords: heavy oil; upgrading; catalysts; aquathermolysis; clay minerals; transition metals; SARA; rheology.

Measurements of Linear and Nonlinear Optical Properties for Iraqi Heavy Crude Oil Samples

In this work, linear and nonlinear optical properties of two types of Iraqi heavy crude oil extracted from fields in southern Iraq were determined. The nonlinear optical properties were measured utilizing Z-scan technology with He-Ne laser at 632.8 nm. It was found that nonlinear refractive index (NLR) values for the Basra and Kut heavy crude oil samples are 6.34381×10-4 and 8.25108×10-4 cm2/mW, respectively, while those for the nonlinear absorption coefficient (NLA) are 2.68942×10-5 and 2.58874×10-5 , respectively. These results showed that the two samples with linear and nonlinear optical properties can be used in optics field applications as optical limiter devices at a wavelength of 632.8 nm.

The effect of shear rate on aggregation and breakage of asphaltenes flocs: Experimental study and model-based analysis

The study of the effect of shear stresses on the aggregation and breakage of asphaltene flocculation is one of the important issues that little research has been done on it. In this paper, the effect of shear rate on the behavior of asphaltene particles of samples including medium and heavy oil in the colloidal state before and after precipitation has been investigated using viscometric method. The physical and chemical properties of dispersed oil systems depend on the particles of asphaltene dispersed in the colloidal state that form complex structural units (CSUs). The size of CSU for two medium and heavy oils was estimated by the Manzhai et al. equation using viscosity data in terms of temperature (T) at different shear rates. By increasing the shear rates from 10 S−1 to 200 S−1, the CSU radius decreases from 155 to 46.1 nm and from 6.64 to 1.27 nm for Azadegan (representative of medium crude oil) and model (representative of heavy crude oil) samples, respectively. Using the generalized Pal–Rhodes equation, the viscosities of heavy oil samples containing different extracted asphaltene contents are predicted at different shear rates. The shape factor at shear rates of 10 and 300 was 6.106 and 4.356, respectively, which indicates that it is approaching the spherical state by increasing the shear rate. Finally, to calculate the effective volume fraction of asphaltene particles in the unsteady state, using the viscosity data of the toluene and crude oil solution and applying the Lobe equation, the viscosity of the background (free-asphaltene) was calculated. With the viscosity of the background and the viscosity data of heptane and crude oil, the amount of effective volume fraction of asphaltene particles was calculated by the Gillespie equation. These values are obtained for three modes: different shear rates, different volume ratios of heptane, and in the presence of two novel inhibitors of cocamide diethanolamine and dodecylbenzene sulfonic acid.

Determination of chloride in crude oil using isotope dilution GC–MS: A comparative study

Optimisation and validation of a novel isotope dilution gas chromatography mass spectrometry (GC–MS) method for determination of inorganic chloride (Cl−) in crude oils is presented. The use of stable isotope dilution calibration approach decreases losses and biases and it is considered a higher order measurement approach. Samples were diluted with a 1:1 blend of isopropyl alcohol : toluene with 5% water, mixed with 37Cl− internal standard, water extracted and derivatized with triethyloxonium tetrafluoroborate at room temperature. This reagent converted Cl− into stable ethyl chloride (EtCl) which was detected by headspace GC–MS. A limit of quantitation of 100 µg kg−1 and limit of detection of 30 µg kg−1 were observed in crude oil samples when initial dilution was not required. The performance of this novel method was compared with combustion ion chromatography, ion chromatography with conductivity detection after microwave-induced combustion, and ASTM D3230 method on a set of medium and heavy crude oil samples. Despite the challenges of the measurement, a reasonable level of agreement was observed among methods over the range of 0.38 ± 0.02 to 993 ± 103 mg kg−1 of Cl−. Presented headspace GC–MS method proved to be suitable for analysis of all types of crude oils samples with an excellent reproducibility (RSD < 6%) and high sample throughput (7 min GC–MS run time).

Qualitative and Quantitative Analysis of Heavy Crude Oil Samples and Their SARA Fractions with 13C Nuclear Magnetic Resonance

Nuclear magnetic resonance (NMR) approaches have unique advantages in the analysis of crude oil because they are non-destructive and provide information on chemical functional groups. Nevertheless, the correctness and effectiveness of NMR techniques for determining saturates, aromatics, resins, and asphaltenes (SARA analysis) without oil fractioning are still not clear. In this work we compared the measurements and analysis of high-resolution 13C NMR spectra in B0 ≈ 16.5 T (NMR frequency of 175 MHz) with the results of SARA fractioning for four various heavy oil samples with viscosities ranging from 100 to 50,000 mPa·s. The presence of all major hydrocarbon components both in crude oil and in each of its fractions was established quantitatively using NMR spectroscopy. Contribution of SARA fractions in the aliphatic (10–60 ppm) and aromatic (110–160 ppm) areas of the 13C NMR spectra were identified. Quantitative fractions of aromatic molecules and oil functional groups were determined. Aromaticity factor and the mean length of the hydrocarbon chain were estimated. The obtained results show the feasibility of 13C NMR spectroscopy for the express analysis of oil from physical properties to the composition of functional groups to follow oil treatment processes.

The effect of water on combustion behavior of crude oils

The ramped temperature oxidation experiments were performed on heavy and light crude oil samples using the TGA and DSC instruments. The crude oils were mixed with different weight percentages (10%, 20%, and 30%) of water, as a result of which six different water-oil mixtures were prepared. The samples were heated up to 800 °C with three heating rates 20, 25, 30 °C/min. Two reaction regions, particularly the low temperature oxidation (LTO) and high temperature oxidation (HTO), were identified in TGA and DSC results. The LTO region can be divided into two subzones as before and after around 150 °C. In the first subzone, up to around 150 °C, the endothermic distillation process took place. The results showed that light crude oil and its mixtures had lower reaction starting and ending temperatures, and peak temperatures compared to heavy crude oil and its mixtures. As the water amount in the mixtures were increased, the reaction and peak temperatures shifted to lower temperatures. The kinetic analysis was also performed applying the Ozawa-Flynn-Wall (OFW), Kissenger-Akahira-Sunose (KAS), and ASTM kinetic methods. The activation energies and Arrhenius constants based on the TGA and DSC results were calculated accordingly. The light crude oil and its water mixtures had lower activation energy and Arrhenius constants compared to heavy crude oil and its mixtures. As the amount of water in the mixture was increased, the activation energy and Arrhenius constant decreased, which indicated that the presence of water in the crude oil increases its ability to combust more efficiently.

Shake, shut, and go – A fast screening of sulfur in heavy crude oils by high-resolution continuum source graphite furnace molecular absorption spectrometry via GeS molecule detection

A fast and simple method for sulfur quantification in crude oils was developed by using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). For this, heavy crude oil samples were prepared as microemulsion (shake) and injected into a graphite furnace (shut). Finally, the concentration of sulfur was determined by monitoring in situ the transient molecular spectrum of GeS at wavelength 295.205 nm after adding a germanium solution as molecular forming agent (and go). Zirconium dioxide in the form of nanoparticles (45–55 nm) was employed as a permanent modifier of the graphite furnace. Calibration was done with an aqueous solution standard of ammonium sulfate, and a characteristic mass (m0) of 7.5 ng was achieved. The effectiveness of the proposed method was evaluated analizing, ten heavy crude oil samples with sulfur amounts ranging between 0.3 and 4.5% as well as two NIST standard reference materials, 1620c and 1622e. Results were compared with those obtained by routine ICP-OES analysis, and no statistical relevant differences were found.

Studies on Naturally Extracted Surfactant to Enhance Flow Properties of Crude Oil

Indian heavy crude oil sample from Gujarat was studied for improvement of properties such as pour point, wax crystal structure, particle size analysis and viscosity by addition of a novel surfactant extracted from a tropical Indian plant Sapindus mukorossi. Characterization was done to find the effect of surfactant addition on individual components of the crude oil such as saturates, asphaltenes, resins and aromatics. The objective was to increase the flowability of the oil and determine which components of the surfactant interact with the crude oil to improve its flow behavior. Heavy crude oil sample was mixed with 4% w/w of Sapindus followed by stirring the samples for one hour and proceeding for tests. The results showed that pour point decreased by a significant amount after adding Sapindus to it and that decrease in pour point was due to reduction in the amount of saturates, aromatics, resins and asphaltenes present in the crude oil. There was a profound reduction in size of wax crystals when investigated under microscopic and particle size analysis. Surfactant addition had a tremendous effect on viscosity. The viscosity of crude oil at 30°C after addition of surfactant, was even less than that of heavy crude without surfactant at 50°C.

Addition of silica nano-particles for the enhancement of crude oil demulsification process

Different chemical demulsifiers were added to heavy Fula crude oil samples (Balila, Sudan) in screen test with and without the addition of silica nanoparticles (NPs). Two particle sizes of 25 nm and 95 nm were investigated using three different concentrations of 30 ppm, 60 ppm and 90 ppm. The addition of silica nanoparticles resulted in a clear improvement in demulsification in most cases. An increase of 150% in water separation was achieved with the addition of 25 nm silica NP suspension in a volume ratio of 1:0.5 (chemical demulsifier to silica nanoparticles) at a concentration of 60 ppm.