Crude Oil Mixtures Research Articles

A Sugar-Based Gelator for Marine Oil-Spill Recovery.

Marine oil spills constitute an environmental disaster with severe adverse effects on the economy and ecosystem. Phase-selective organogelators (PSOGs), molecules that can congeal oil selectively from oil-water mixtures, have been proposed to be useful for oil-spill recovery. However, a major drawback lies in the mode of application of the PSOG to an oil spill spread over a large area. The proposed method of using carrier solvents is impractical for various reasons. Direct application of the PSOG as a solid, although it would be ideal, is unknown, presumably owing to poor dispersion of the solid through the oil. We have designed five cheap and easy-to-make glucose-derived PSOGs that disperse in the oil phase uniformly when applied as a fine powder. These gelators were shown to selectively congeal many oils, including crude oil, from oil-water mixtures to form stable gels, which is an essential property for efficient oil-spill recovery. We have demonstrated that these PSOGs can be applied aerially as a solid powder onto a mixture of crude oil and sea water and the congealed oil can then be scooped out. Our innovative mode of application and low cost of the PSOG offers a practical solution to oil-spill recovery.

Computer Aided Design of a Multi-Component Distillation Column for Processing of Nigerian Bonny Light Crude Oil

The design of the multi-component distillation column for processing of Bonny light crude is presented using advanced process simulation software (Aspen Hysys). The steady state design models were developed from Mesh equations and were used to obtain the design parameters based on the principle of conservation of mass and energy. The design parameters were column diameter, column cross sectional area, height of the column, downcomer area, hole area, weir length, wet area and tray spacing. The equations developed are capable of predicting compositions, partial pressures and temperature of the components of interest from the mixtures of crude oil. The accuracy of the design parameters were ascertained by comparing predicted results with literature data of a distillation unit. The simulation of the design models were performed using Aspen Hysys to obtain optimum values of the most significant variables/parameters (column diameters 1.558m, column height 17.048m, cross section area 1.907m2, downcomer area 0.229m2, tray spacing 0.5m, weir length 1.200m, hole area 0.191m2 and wet area 1.678m2). The result obtained from the steady state simulation shows that the feed flow rate, temperature and pressure influence the efficiency of the distillation column.

Modeling of Pressure Dependence of Interfacial Tension Behaviors of a Complex Supercritical CO2 + Live Crude Oil System Using a Basic Parachor Expression

Parachor based basic expressions are often used to model the experimentally observed pressure dependence of interfacial tension (IFT) behaviors of complex supercritical CO2 + crude oil (dead or live) mixtures at elevated temperatures. However, such modeling requires compositions and densities of the equilibrium liquid and vapor phases and molecular weights of various components present in the system. In the absence of measured data, often phase behavior packages are used for obtaining these input data for performing calculations. Very few researchers have used experimentally measured input data for performing parachor based modeling of the experimental IFT behaviors of complex supercritical CO2 + live crude oil systems. This study presents the results of a basic parachor model based modeling of pressure dependence of IFT behaviors of a complex supercritical CO2 + live crude oil system for which experimentally measured input data is available in public domain. Though the calculated IFT behaviors showed significant deviation from the experimentally measured behaviors at a given pressure, calculated IFT versus pressure trends appeared to follow the experimental observed trends closely. Also, despite a large variation in the compositions of feed supercritical CO2 + live crude oil mixtures, both trends (calculated and experimental) converged rapidly to attain a near zero IFT condition at more or less same pressure.

Determination of Simulated Crude Oil Mixtures from the North Sea Using Atmospheric Pressure Photoionization Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Defined artificial mixtures of crude oils from the North Sea were analyzed using atmospheric pressure photoionization coupled to Fourier transform ion cyclotron resonance mass spectrometry (APPI FT-ICR MS). The main objective was the evaluation of the accurate determination of calculated mixing ratios of similar crude oils. The mixing ratios of two oils were determined on the basis of the relative abundances of the main compound classes detected as protonated species and radical cations. The calculation of the ratios of ternary mixtures was based on two different approaches. The first approach used the relative abundances of the main compound classes in combination with the non-negative least squares (NNLS) method. The second approach used principal component analysis (PCA) using the first and second principal components (PC1 and PC2) of the pure oils and defined ternary mixtures to generate a ternary PCA scoring plot. The exact compositions of three ternary mixtures were calculated on the basis of the me...

Selective Analysis of Sulfur-Containing Species in a Heavy Crude Oil by Deuterium Labeling Reactions and Ultrahigh Resolution Mass Spectrometry.

A heavy crude oil has been treated with deuterated alkylating reagents (CD3I and C2D5I) and directly analyzed without any prior fractionation and chromatographic separation by high-field Orbitrap Fourier Transform Mass Spectrometry (FTMS) and Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS) using electrospray ionization (ESI). The reaction of a polycyclic aromatic sulfur heterocycles (PASHs) dibenzothiophene (DBT), in the presence of silver tetrafluoroborate (AgBF4) with ethyl iodide (C2H5I) in anhydrous dichloroethane (DCE) was optimized as a sample reaction to study heavy crude oil mixtures, and the reaction yield was monitored and determined by proton nuclear magnetic resonance spectroscopy (1H-NMR). The obtained conditions were then applied to a mixture of standard aromatic CH-, N-, O- and S-containing compounds and then a heavy crude oil, and only sulfur-containing compounds were selectively alkylated. The deuterium labeled alkylating reagents, iodomethane-d3 (CD3I) and iodoethane-d5 (C2D5I), were employed to the alkylation of heavy crude oil to selectively differentiate the tagged sulfur species from the original crude oil.

Rethinking the modeling approach for asphaltene precipitation using the PC-SAFT Equation of State

The Perturbed Chain version of the Statistical Associating Fluid Theory Equation of State (PC-SAFT EoS) has been successfully applied to the modeling of the phase behavior of petroleum systems at reservoir conditions and the prediction of asphaltene precipitation. Although the predictive capabilities of this method and its wide range of applications are much better than other modeling techniques based on conventional cubic equations of state, there are certain features that are still missing, such as the polydisperse nature of asphaltenes. Furthermore, the simulation parameters are usually tuned to Asphaltene Onset Pressure (AOP) data –which are usually obtained by depressurizing live oil samples− or titration experiments of dead oil samples at ambient conditions. These techniques are subject to significant uncertainties caused by slow kinetics of asphaltene aggregation and the limited sensitivity of the instruments used. The focus of this work is on the experimental study and modeling of asphaltene precipitation from n-alkane - diluted crude oil mixtures considering the polydispersity of asphaltenes. To investigate the effect of asphaltene polydispersity, a crude oil sample is studied by sequential precipitation with different normal alkanes. A recently developed experimental technique called the “Indirect Method” is used for the detection and quantification of asphaltene precipitation. Based on our previous research using the indirect method, it was found that both the onset and the amount of asphaltene precipitation change with the aging time for a wide range of volume fractions of the added n-alkane. However, the data showed that the amount of precipitated asphaltene at 90 volume percent of a given precipitant is nearly time invariant. This experimental data point is not controlled by the kinetics of asphaltene aggregation and, for this reason, is used in this study to adjust the simulation parameters. The experimental data are modeled using the Perturbed Chain form of the Statistical Associating Fluid Theory. An enhanced characterization method is used to minimize the number of adjustable parameters. In this work, a distribution function is proposed to represent the asphaltene molecular weight distribution for different asphaltene sub-fractions. It has been found that the inclusion of four asphaltene sub-fractions to represent the polydispersity of asphaltenes is necessary to match the amount of asphaltene precipitated. The modeling results show a reasonable agreement for the precipitated amount at 90 volume percent of n-pentane, n-hexane, n-heptane and n-octane. The PC-SAFT EoS predicts an onset point that requires less addition of n-alkane than the corresponding experimental point after one day of aging time. This result suggests that a thermodynamic limit exists for the onset of asphaltene precipitation and that it corresponds to experiments that require very long aging times, as it has been previously reported by Maqbool et al. [1]. By fitting the simulation parameters to the amount of precipitated asphaltenes (and not the detected onset points) at 90 volume percent of added asphaltene precipitant, we can successfully remove the variability of the data with respect to the aging time. This tuning procedure also enables a more accurate prediction of the amount of precipitated asphaltenes at reservoir conditions, which is a more important result for the modeling of asphaltene deposition than the Asphaltene Onset Point itself. The integration of this novel characterization procedure as part of the Asphaltene Deposition Tool (ADEPT) [2–4] developed at Rice University is a topic of ongoing research.

Crude Oil Corrosion Fatigue of L485MB Pipeline Steel

An investigation was made into the fatigue properties of L485MB (X70) pipeline steel after 13 yr of exploitation as a crude oil pipeline material. Fatigue tests in zero-to-tension loading were carried out (i) in air, (ii) in crude oil, (iii) in a mixture of crude oil with rainwater, and (iv) in water separated from the crude oil phase. The aim of the investigation was to assess the degree of degradation of the fatigue properties of this steel due to the action of environments typical for crude oil processing and transport. The results are not directly comparable to any corrosion fatigue experienced by the crude oil pipeline, since the strain rate for the tests was higher by an order of five than the strain rate observed in typical loading cycles. The results showed that crude oil and a mixture of crude oil with rainwater had no aggressive effect on the steel in the sense of reducing its fatigue characteristics, while the separated water had an aggressive effect.

The effects of N, P and crude oil on the decomposition of Spartina alterniflora belowground biomass

We conducted a laboratory experiment to examine how the decomposition of particulate belowground organic matter from a salt marsh is enhanced, or not, by different mixtures of crude oil, nitrogen (N), or phosphorus (P) acting individually or synergistically. The experiment was conducted in 3.8 L sampling chambers producing varying quantities of gas whose volume was used as a surrogate measure of organic decomposition under anaerobic conditions. Gas production after 28 days, from highest to lowest, was +NP = +N >>> +P, or +oil. The gas production under either +P or +oil conditions was indistinguishable from gas production in the control chamber. Nitrogen, not phosphorus, or +NP, was the dominant factor controlling organic decomposition rates in these experiments. The implication for organic salt marsh soils is that shoreline erosion is enhanced by salt marsh oiling, presumably by its toxicity, but not by its effect on the decomposition rates of plant biomass belowground. Nutrient additions, on the other hand, may compromise the soil strength, creating a stronger disparity in soil strength between upper and lower soil layers leading to marsh loss. Nutrient amendments intended to decrease oil concentration in the marsh may not have the desired effect, and are likely to decrease soil strength, thereby enhancing marsh-to-water conversions in organic salt marsh soils.

A Group Contribution Pseudocomponent Method for Phase Equilibrium Modeling of Mixtures of Petroleum Fluids and a Solvent

We present a group contribution pseudocomponent (PC) method for mixtures of petroleum fluids and a solvent based on the characterization method (CM) for petroleum fractions and the predictive Peng–Robinson 1978 (PPR78) model. The objective of this study is to model the phase equilibrium of crude oil and a solvent consisting of one or multiple pure components. We develop a structural analysis of crude oil to bridge the CM and the PPR78 model, which predicts the temperature-dependent binary interaction parameters (BIP) among the PCs and pure components. The predicted results using our method agree well with experimental data for mixtures of oil sand bitumen and propane, CO2, or water. The approach is applicable to phase equilibrium predictions of mixtures of crude oil and water over a wide range of temperatures (273–644 K or higher as reasonable extrapolations) and pressures (4 kPa–26 MPa).

Reception, mixture, and transfer in a crude oil terminal

The aim of this work is the modeling and validation of a process of reception, mixture and delivery of crude oil in a terminal. Each tank at the terminal receives different oil qualities from different cargos. Constraints are imposed to ensure material balance and operating rules. Inventory levels in the tanks are discretized. Crude oil should be transferred to the refinery according to a schedule of volumes and qualities. Linear constraints with an adjustment term for composition discrepancies are formulated to force the concentration in a tank to be equal to the concentration of the outlet volume. The problem consists in finding an optimized schedule that meets the constraints. A MILP model is proposed and solved for specific cases. In order to achieve good results in an affordable time, the rolling horizon strategy (RHS) is applied to determine the optimal schedule of crude oil operations over a time horizon.

Prediction of Asphaltene Precipitation by Using an Association Equation of State

In this work, a new and efficient algorithm for asphaltene deposition modeling through application of an association thermodynamic model is introduced. It is assumed that pure asphaltene component only participates in the deposition phase. For characterization of asphaltenes, a two-phase flash calculation and cubic equation of state (Peng-Robinson equation of state) were used to describe asphaltene-toluene mixture (non-association mixture) and vapor-liquid equilibria, in which the critical properties of pure asphaltene component for the initial guess are adjusted with experimental data. Some of the association equation of state (AEOS) are selected for asphaltene modeling in a crude oil system as association mixture, which gives accurate results for water. To extend the model to crude oil mixtures, AEOS and vapor-liquid-deposition phase three-phase flash calculation are used to obtain the amount of asphaltene deposition and association model parameters. The authors’ experimental data from the Iranian crude oil reservoir, in this study, were used to examine the proposed asphaltene association model. It has been shown that the calculated results are in good agreement with the experimental data.

Experimental and Modeling Investigations of the Viscosity of Crude Oil Binary Blends: New Models Based on the Genetic Algorithm Method

Achieving an estimation of viscosity in crude oil binary mixtures is often difficult because the relationship of viscosity, to the fraction of each crude oil, and many other parameters and constants is comply. This relationship can be expressed by mathematical models with different variables. Besides the known models for predicting the viscosity of crude oil mixtures, the petroleum industry demands other models which give accurate predictions. In this work, two new empirical models have been developed for the calculation of the viscosity of binary crude oil blends. Two techniques—least square (LS) and genetic algorithm (GA)—were used to determine the parameters of the proposed models. Dynamic viscosity of 12 sets of crude oil blends at 298.15 K and 25 different shear rates were measured, resulting in 300 sets of binary data. Moreover, 700 sets of kinematic viscosity binary data were collected from literature sources and used along with 200 of the 300 sets of experimental binary data with a wide range of American Petroleum Institute (API) gravity (9.89–41.2) and viscosity (1.054–165,860 cSt) to examine existing available models as well as the newly developed models in this study. The remaining 100 experimental data points which were not used in the regression process were used for validating the models. The results in terms of the absolute average relative deviation (AARD%) were 33.546 and 14.195 for the LS method and 13.113 and 13.672 for the GA method for proposed models one and two, respectively. The results of statistical parameters based on the GA and LS methods showed that the GA is a superior method for new model parameter estimation as compared with the traditional LS technique. The GA-based models developed in this study provided the highest accuracy for viscosity calculation of the crude oil blends over all existing models in the literature.

The effect of oil spills on the bacterial diversity and catabolic function in coastal sediments: a case study on the Prestige oil spill.

The accident of the Prestige oil tanker in 2002 contaminated approximately 900 km of the coastline along the northern Spanish shore, as well as parts of Portugal and France coast, with a mixture of heavy crude oil consisting of polycyclic aromatic hydrocarbons, alkanes, asphaltenes and resins. The capacity of the autochthonous bacterial communities to respond to the oil spill was assessed indirectly by determining the hydrocarbon profiles of weathered oil samples collected along the shore, as well as through isotope ratios of seawater-dissolved CO2, and directly by analyses of denaturing gradient gel electrophoresis fingerprints and 16S rRNA gene libraries. Overall, the results evidenced biodegradation of crude oil components mediated by natural bacterial communities, with a bias towards lighter and less substituted compounds. The changes observed in the Proteobacteria, the most abundant phylum in marine sediments, were related to the metabolic profiles of the sediment. The presence of crude oil in the supratidal and intertidal zones increased the abundance of Alpha- and Gammaproteobacteria, dominated by the groups Sphingomonadaceae, Rhodobacteraceae and Chromatiales, whilst Gamma- and Deltaproteobacteria were more relevant in subtidal zones. The phylum Actinobacteria, and particularly the genus Rhodococcus, was a key player in the microbial response to the spill, especially in the degradation of the alkane fraction. The addition of inorganic fertilizers enhanced total biodegradation rates, suggesting that, in these environments, nutrients were insufficient to support significant growth after the huge increase in carbon sources, as evidenced in other spills. The presence of bacterial communities able to respond to a massive oil input in this area was consistent with the important history of pollution of the region by crude oil.

Experimental and modeling studies of phase behavior for propane/Athabasca bitumen mixtures

Recent developments in heavy oil recovery methods indicate that the co-injection of solvent and steam can result in higher oil production rates. To investigate the performance and gain a better understanding of this newly developed process, it is essential to study the phase behavior of solvent/heavy crude oil mixtures and measure the saturated phase properties. This study attempts to provide insight into the phase behavior of propane/bitumen mixtures over wide ranges of temperatures and pressures, where the conditions would be applicable for both Vapex and ES-SAGD processes. Thus, phase behavior experiments for propane/Athabasca bitumen mixtures were conducted over temperature range of 323–473K and at pressures up to 10MPa. The results indicate that the mixture of propane and bitumen forms vapor–liquid and liquid–liquid phase separations over the studied temperature and pressure ranges. The variation of solubility with equilibrium pressure was found to be more significant at low temperatures. There were crossovers for gas-saturated bitumen density and viscosity which highlights the effect of solubility at low temperatures that is more significant than the effect of temperature on the bitumen density and viscosity. Thus, lower saturated properties were obtained at low temperatures and high pressures. The solubility and saturated liquid density were well predicted by Peng–Robinson equation of state and the saturated bitumen viscosities were reasonably correlated with Pedersen’s correlation.

Dissipative particle dynamics simulation on the rheological properties of heavy crude oil

The rheological properties of heavy crude oil have a significant impact on the production, refining and transportation. In this paper, dissipative particle dynamics (DPD) simulations were performed to study the effects of the addition of light crude oil and emulsification on the rheological properties of heavy crude oil. The simulation results reflected that the addition of light crude oil reduced the viscosity effectively. The shear thinning behaviour of crude oil mixtures were becoming less distinct as the increase of the mass fraction of light crude oil. According to the statistics, the shear had an influence on the aggregation and spatial orientation of asphaltene molecules. In addition, the relationship between the viscosity and the oil mass fraction was investigated in the simulations of emulsion systems. The viscosity increased with the oil mass fraction slowly in oil-in-water emulsions. When the oil mass fraction was higher than 50%, the increase became much faster since systems had been converted into water-in-oil emulsions. The equilibrated morphologies of emulsion systems were shown to illustrate the phase inversion. The surfactant-like feature of asphaltenes was also studied in the simulations.

High quality genome sequence and description of Enterobacter mori strain 5-4, isolated from a mixture of formation water and crude-oil.

Enterobacter mori strain 5–4 is a Gram-negative, motile, rod shaped, and facultatively anaerobic bacterium, which was isolated from a mixture of formation water (also known as oil-reservior water) and crude-oil in Karamay oilfield, China. To date, there is only one E. mori genome has been sequenced and very little knowledge about the mechanism of E. mori adapted to the petroleum reservoir. Here, we report the second E. mori genome sequence and annotation, together with the description of features for this organism. The 4,621,281 bp assembly genome exhibits a G + C content of 56.24% and contains 4,317 protein-coding and 65 RNA genes, including 5 rRNA genes.Electronic supplementary materialThe online version of this article (doi:10.1186/1944-3277-10-9) contains supplementary material, which is available to authorized users.

Desolventizing organic solvent-soybean oil miscella using ultrafiltration ceramic membranes

This work reports the use of ceramic membranes with different cut-offs (5, 10 and 20kDa) for the separation of synthetic mixtures simulating soybean oil industrial miscellas in organic solvents (n-hexane, ethanol and isopropanol). The mass ratios oil/solvent investigated in this work were 1:4, 1:3 and 1:1 (w/w) for the feed pressures of 0.5–4bar depending on the miscella. It is shown that n-butanol was the best solvent for the proper conditioning of 20kDa membrane, since it increased permeate flux of n-hexane, up to 314L/m2h at 1bar of transmembrane pressure. The desolventizing of oil/solvent mixtures was strongly affected by solvent nature, and on the solute–solvent–membrane affinity. The highest retentions were observed for oil/ethanol mixtures, with values usually close to 100%, as a consequence of polarity as well as low solvation power. Crude oil mixture with n-hexane (industrial mixture) yielded greater retention and lower flux than those obtained with refined oil, due to the polarized layer formed by gums and phospholipids. Results reported in this work indicate the potential applicability of this technology in vegetable oil processing and biodiesel industries in the solvent recovery step.

TOXICITY EFFECT OF OIL SPILL DISPERSANTS ON LITOPENAEUS VANNAMEI

One of the most chemical methods for controlling of oil spills is use of dispersants, which are widely being used worldwide. In this research, comparison of acute toxicity of crude oil of the Persian Gulf- Khark area (CO), Iranian Naftroob crude oil dispersant (IND), Radiagreen OSD dispersant crude oil (RD), the mixture of crude oil and Iranian Naftroob dispersant ( CO-IND) and crude oil with Radiagreen OSD dispersant (CO-RD) was carried out. For this purpose, the concentrations of both dispersants were equal: 10.5, 21, 42, 84 and 168 mg/L. The concentrations of 8.4+16, 16.8+336, 33.6+672, 67.2+1344 and 134.4+2688 mg/L were used for dispersants-crude oil mixtures and the concentrations of 168, 336, 672, 1344 and 2688 mg/L were used for crude oil alone. Litopenaeus vannamei was used for bioassay toxicity test. 48-h LC50 was estimated by Probit value table. Relationship between efficiency and toxicity (RET) was also estimated. 48-h LC50 for CO, IND, RD, CO-IND and CO-RD were 1741, 17.21, 43.52, 631.456, 357.089 mg/L, respectively. The results were obtained by these tests were shown that CO alone is less toxic than the IND, RD and also CO- IND and CO-RD. Moreover, CO-IND was less toxic than CO-RD. With regard to the efficiency of IND had a lower (RET = 34.8) than RD (RET = 39) and so, it was more efficient.

Biological souring of crude oil under anaerobic conditions

Seawater injection into oil reservoirs for purposes of secondary oil recovery is frequently accompanied by souring (increased sulfide concentrations). Production of hydrogen sulfide causes various problems, such as microbiologically influenced corrosion (MIC) and deterioration of crude oil. Sulfate-reducing bacteria (SRB) are considered to be major players in souring. Volatile fatty acids (VFAs) in oil-field water are believed to be produced by microbial degradation of crude oil. The objective of this research was to investigate mechanisms of souring, focusing specifically on VFA production via crude oil biodegradation. To this end, a microbial consortium collected from an oil–water separator was suspended in seawater; crude oil or liquid n-alkane mixture was added to the culture medium as the sole carbon source, and the culture was incubated under anaerobic conditions for 190 days. Physicochemical analysis showed that preferential toluene degradation and sulfate reduction occurred concomitantly in the culture containing crude oil. Sulfide concentrations were much lower in the alkane-supplemented culture than in the crude oil-supplemented culture. These observations suggest that SRB are related to the toluene activation and VFA consumption steps of crude oil degradation. Therefore, the electron donors for SRB are not only VFA, but many components of crude oil, especially toluene. Alkanes were also degraded by microorganisms, but did not contribute to reservoir souring.

Online normal-phase high-performance liquid chromatography/Fourier transform ion cyclotron resonance mass spectrometry: effects of different ionization methods on the characterization of highly complex crude oil mixtures.

Characterization of crude oil represents a challenge for researchers due to its complexity. While Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is the method of choice for such complex matrices the high number of ions present limits the efficiency of the analysis due to charge competition and space charge effects. One way to solve this problem is the direct coupling of FT-ICR MS with high-performance liquid chromatography (HPLC). Normal-phase liquid chromatography was applied on a deasphalted crude oil sample by using a polar aminocyano-bonded stationary phase with n-hexane and isopropyl alcohol as a mobile phase. The HPLC system was coupled online to a 12 T ultrahigh-resolution FT-ICR mass spectrometer. Ion chromatograms were obtained with electrospray ionization (ESI), atmospheric pressure photoionization (APPI), atmospheric pressure chemical ionization (APCI), and atmospheric pressure laser ionization (APLI). The chromatographic separation yielded a group separation into two peaks according to the polarity of the components. Each ionization technique was able to uniquely assign components differing in polarity and aromaticity. Additionally, an increase in aromaticity in the course of retention time for nonpolar species in the first peak was observed. Monitoring the ratio between protonated and radical mono-nitrogen species was achieved. For the analysis of a crude oil sample, online coupling of a normal-phase HPLC system to an FT-ICR mass spectrometer was achieved. The results of the different ionization techniques were compared with each other, which enables a detailed characterization of the complex sample. Copyright © 2014 John Wiley & Sons, Ltd.