Analysis Of Crude Oil Samples Research Articles

Robust principal component analysis-multivariate adaptive regression splines (rPCA-MARS) model for determining total acid number (TAN) and total base number (TBN) of crude oil samples using attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy

Rapid assessments of Total Acid Number (TAN) and Total Base Number (TBN) in crude oil samples are significant in the oil industry. The analysis of TAN and TBN was conducted using the standard methods of the American Society for Testing and Materials (ASTM). However, the standard methods are costly and require a large number of samples for analysis. Therefore, providing analytical methods for the rapid crude oil analysis is very essential. In the current research, we report an application of Attenuated Total Reflection Fourier-Transform Infrared (ATR-FTIR) spectroscopy, based on robust Principal Component Analysis-Multivariate Adaptive Regression Splines (rPCA-MARS), for crude oil analysis. In the rPCA-MARS model, the ATR-FTIR spectral matrix data was decomposed into PCs scores using the rPCA method as an input data for the MARS model. The multivariate calibration models were applied to the analysis of crude oil samples based on the quantitative determination of total acid number (TAN) and total base number (TBN). An analytical method was developed for determination of TAN and TBN of crude oil samples. The ATR-FTIR spectroscopy coupled with multivariate calibration methods can be applied as a novel analytical method for crude oil samples. The result of partial least square regression (PLS-R), principle component analysis (PCR), Piecewise-Linear rPCA-MARS and Piecewise-cubic rPCA-MARS models were compared for analysis of total acid and base number of crude oil samples. The squared correlation coefficient (R2) and root mean square error (RMSE) for calibration and prediction sets were calculated to evaluate multivariate calibration models. The importance of methods was studied and discussed. The mean square error (MSE) values of Piecewise-Linear rPCA-MARS for TAN and TBN were 1.587 * 10−4 and 0.009, respectively. The Piecewise-Linear rPCA-MARS model can be successfully applied for the analysis of TAN and TBN of crude oil samples based on the obtained results. The fast and easy prediction capability of the proposed Piecewise-Linear rPCA-MARS model, as compared to standard methods, for determining TAN and TBN without any sample preparation step is important in the oil industry

Preparation of a novel chromatographic material and its application for spectroscopic characterization of aromatics in crude oil

Petroleum analysis presents many unique challenges as a result of the chemical complexity of petroleum composition. In the present work a novel chromatographic material has been developed and utilized to separate crude oils. A total number of 13 fractions have been collected using different solvent mixtures with increasing proportions of chloroform. UV and IR spectroscopy has been employed to show that the size of the aromatic ring system increases and the extent of molecular branching decreases with elution gradient. This observation suggests that intermolecular non-covalent π-π interactions between the material and the sample molecules are critical to the separation. This novel method for sequencing petroleum molecules based on the size of the aromatic ring systems has been applied to the 2D off-line analysis of crude oil samples. The 2D on-line separation (NPLC × NPLC) has been simulated by 2D off-line separation. A total number of 38 fractions have been obtained with two SPE columns based on the molecular branching and the aromatic ring system size. The chemical information obtained in this study of North Sea crude oil is complementary to standard SARA analysis. The material supports a potential solution to overcome the challenges of tandem NPLC and has demonstrated a new approach to the separation of crude oils into discrete compound classes.

Genetic algorithm based support vector machine regression for prediction of SARA analysis in crude oil samples using ATR-FTIR spectroscopy.

In the current research, an analytical method was proposed for rapid quantitative determination of saturates, aromatics, resins and asphaltenes (SARA) fractions of crude oil samples. Rapid assessments of SARA analysis of crude oil samples are of substantial value in the oil industry. The conventional SARA analysis procedures were determined with the standards established by the American Society for Testing and Materials (ASTM). However, the standard test methods are time consuming, environmental nonfriendly, expensive, and require large amounts of the crude oil samples to be analyzed. Thus, it be would useful to approve some supportive approaches for rapid evaluation of the crude oils. The attenuated total reflection Fourier-transform infrared spectroscopy ATR-FTIR coupled with chemometric methods could be used as analytical method for crude oil analysis. A hybrid of genetic algorithm (GA) and support vector machine regression (SVM-R) model was applied to predict SARA analysis of crude oil samples from different Iranian oil field using ATR-FTIR spectroscopy. The result of GA-SVM-R model were compared with genetic algorithm-partial least square regression (GA-PLS-R) model. Correlation coefficient (R2) and root mean square error (RMSE) for calibration and prediction of samples were also calculated, in order to evaluate the calibration models for each component of SARA analysis in crude oil samples. The performance of GA-SVM-R is found to be reliably superior, so that it can be successfully applied as an alternative approach for the quantitative determination of the SARA analysis of crude oil samples.

Characterizing the wax-asphaltene interaction and surface morphology using analytical spectroscopy and microscopy techniques

In this study, the effect of wax-asphaltene molecular interaction and crude oil property on the amount of wax appearance temperature (WAT) along with the size and morphology of the wax crystals were investigated. For this purpose, three crude oil samples selected, and their WAT value is determined using a cross-polarized microscope (CPM) method. The spectroscopy analysis of crude oil samples demonstrated that the morphology of wax crystals in CPM images depends mainly on the functional groups existing in crude oil. The presence of polar functional groups such as hydroxyl, increasing the aliphatic compounds, and reducing the percentage of aromatics in crude oil leads to wax crystals to become rounded, and their uniformity rise. The size of the wax crystals is associated with the crude oil aromaticity index. Increasing the aromatic rings in the structure of crude oil creates larger wax crystals. However, the amount of WAT depends on the molecular structure of the wax and asphaltene besides their interaction. If the wax molecule is mainly paraffinic and the percentage of cyclic compounds is low, the interaction between the poly-aromatic asphaltene molecule with the wax molecules significantly decreases; thus, the asphaltene cannot act as a nucleation point for the wax particles, and the WAT value reduces. The shape of the wax particles in SEM images is closely related to its molecular structure. If the wax constituent of crude oil is microcrystalline, the interaction between the wax and asphaltene increases. Therefore, the wax particles will be observed rounded under SEM. If the wax has both cyclic and paraffinic compounds, its crystals will be seen in the plate-type form. Furthermore, if the wax constituent is macrocrystalline, the wax particles will have a hive-type shape and cover the entire surface of the image.

Smartphone compatible on-site fluorescence analyzer for spilled crude oil based on CMOS image sensor

Oil spills, both in the ocean and inland waters, have negative effects such as mass mortality and habitat destruction. In this study, we develop a spilled oil point-of-testing device (SOPD), a field measurement system for immediate on-site fluorescence monitoring of oil concentrations. Photodetectors, such as photodiodes and photo multiplier tubes, which are commonly used in existing instrumentation, have inherent limitations because they are capable of only single-pixel detection. However, SOPD can cope with environmental noise caused by dust, dirt, and impurities, by adopting a multi-mega pixel complementary metal-oxide semiconductor image sensor as a detector. Furthermore, the manufacturing cost is remarkably reduced by a simple optical configuration using only two light-emitting diode light sources, five optical lenses, and a CMOS sensor. SOPD can quantitatively analyze fluorescence intensities at both low (0–1 ppm) and high (1–800 ppm) concentrations in marine and inland environments, respectively. The performance of the equipment reported in this paper was demonstrated by measuring the linear measurement range and the limit of detection using five different kinds of crude oil. A correlation analysis of crude oil samples having different collection dates was also completed. In addition, SOPD has been developed as a remote system that can be operated and analyzed on a smartphone, thereby enhancing user convenience, reducing analysis time, and simplifying device.

Characteristic and discrimination of unconventional oil samples by two‐dimensional extraction combined with concentration‐resolved fluorescence spectroscopy

AbstractFluorescence detection of petroleum related samples has excellent application value for unconventional oil exploration and petrochemical detection. In this paper, based on the concentration‐resolved fluorescence spectra, the synchronous fluorescence spectra were used in the range of 3.0 × 10−3 g/L to 5.0 g/L for different kinds of petroleum samples and petrochemical products with n‐hexane and isopropanol as extractants. A red shift of the fluorescence spectra with an increase in the concentration was found under both extractants. The solubility of n‐hexane on crude oil was stronger while that of isopropanol was better for aromatic compounds. The results show that the effect of different extracting agents on the spectra can be used to acquire more information about aromatics components in petroleum related samples, which should be carefully considered in the process of quantitative and qualitative analysis of crude oil samples by fluorescence spectra. It is also shown that the combined extraction of different extractants could enhance the analytical ability of the fluorescence spectrometry, and the rapid, non‐contact measurement is promising for in‐field use.

Crude oil characterization using TGA-DTA, TGA-FTIR and TGA-MS techniques

In this research, combustion characterization and kinetics of four different origin crude oil samples were determined using thermogravimetry - differential thermal analysis (TGA-DTA) and thermogravimetry - Fourier transform infrared (TGA-FTIR) and thermogravimetry – mass spectrophotometry (TGA-MS) techniques.In the TGA-DTA analysis of crude oil samples, low temperature oxidation (LTO) and high temperature oxidation (HTO) reaction regions were observed in different temperature intervals. On the other hand, reaction regions, mass loss, and peak-burnout temperatures of the crude oil samples were also determined using TGA-DTA curves. In TGA-FTIR analysis, spectrums of crude oil samples were examined at different time intervals and composition of several hydrocarbon compounds was determined quantitatively. This research was also focused on the main volatile products (H2, H2O, CO, CO, C6H6, SO2 etc…) of different origin crude oil samples on the basis of both their relative intensities and on their relevancy by using TGA-MS technique.Two different Arrhenius types of kinetic models were used in order to determine the kinetic triplets (activation energy, Arrhenius constant and reaction order) of crude oil samples studied. It was observed that in HTO region, higher activation energy values were observed depending on the °API gravities of the crude oils.

Integrating comprehensive two-dimensional gas chromatography and downhole fluid analysis to validate a spill-fill sequence of reservoirs with variations of biodegradation, water washing and thermal maturity

Optimization of production depends heavily on crude oil composition and its variation within and across multiple reservoirs. In particular, asphaltene content has enormous impact on crude oil viscosity and the economic value of reservoir fluids. Thus, it is important to understand the primary controls on crude oil composition and asphaltene distributions in reservoirs. This paper examines a complex oilfield in the North Sea that contains seven separate reservoirs. The crude oil is believed to have spilled from deeper into shallower reservoirs during reservoir charging. In-situ asphaltene content is measured by downhole fluid analysis (DFA) and is generally consistent with a spill-fill sequence in reservoir charging. Detailed compositional analysis of crude oil samples by comprehensive two-dimensional gas chromatography (GC×GC) was used to determine the extent of water washing, biodegradation and thermal maturity among the reservoirs. Increased biodegradation and water washing in the shallower reservoirs is consistent with a spill-fill sequence. Aromatic and alkylated aromatic compounds decrease according to a combination of water solubility and susceptibility to biodegradation in the shallower reservoirs. Four thermal maturity biomarker ratios show that the shallower reservoirs contain less mature oil, consistent with a spill-fill sequence. The combination of DFA for bulk compositional analysis and GC×GC for detailed compositional analysis combined with geochemical interpretation is an effective tool to unravel complex oilfield scenarios.

Multi-element analysis of crude oils using ICP-QQQ-MS

Determination of trace element contents in crude oils constitutes a powerful geochemical tool, complementing organic geochemical analyses and allowing a deeper insight into the processes of oil generation, migration and maturation. Inductively coupled plasma mass spectrometry (ICP-MS) has been widely applied to trace element determination in petroleum samples due to its low detection limits and fast multi-element capability. However, quantification of several elements by quadrupole-based ICP-MS is hampered by low sensitivity due to high ionisation energy, severe polyatomic interferences and/or low abundance. In the present contribution an ICP tandem mass spectrometer (ICP-MS/MS), or triple quadrupole ICP-MS (ICP-QQQ-MS) has been used to overcome these limitations. Prior to analysis, samples were subjected to high pressure acid digestion, allowing external calibration by means of aqueous standards. 25 elements, including P, S, the first-row transition metals, As, Se, Re, Pb and U, could be quantified in one measurement. Polyatomic interferences on the lighter elements could be removed by reaction of the target ions with O2 or NH3 in the collision/reaction cell of the ICP-MS/MS. The accuracy of the analytical method was assessed by the analysis of the standard reference materials NIST SRM 1634c (trace elements in fuel oil) and 1084a (wear-metals in lubricating oil). The measurement procedure was applied to the analysis of crude oil samples from the Alpine Foreland Basin of Austria.

Determination of asphaltene precipitation conditions during natural depletion of oil reservoirs: A robust compositional approach

Asphaltene precipitation causes rigorous problems in petroleum industry such as: relative permeability reduction, wettability alteration, blockage of the flow, etc. Therefore, accurate determination of onset pressures of asphaltene precipitation is necessary. These pressures can be obtained by experimental measurements on representative samples of the crude oils; however, laboratory analysis of crude oil samples is costly, time consuming and cumbersome. In this communication, three simple and accurate expressions have been proposed for prediction of lower and upper onset pressures of asphaltene precipitation as well as saturation pressures. To this end, 33 crude oil samples were collected from open literature sources. Afterward, two constrained multivariable search methods, namely generalized reduced gradient (GRG) and successive linear programming (SLP), were employed for modeling and expediting the process of achieving a good feasible solution. Then, comparative studies were conducted between the developed equations and equations of state as well as empirical correlations. The results illustrate that the developed equations are accurate, reliable and superior to all other published models. The results show that the proposed equations can predict lower onset pressure, upper onset pressure and saturation pressure with average absolute percent relative errors of 5.04%, 3.93%, and 3.81%, respectively. Besides, it is found that molecular weight of heptane-plus fraction has the greatest impact on the lower onset pressure, while methane has the most significant effect on both of the saturation and upper onset pressures.

Elemental Analysis of Crude Oils Using Microwave Plasma Atomic Emission Spectroscopy

Trace elemental analysis using microwave-induced plasma (MP) generated by nitrogen gas was employed as an atomization and excitation source for emission spectrometric (microwave plasma atomic emission spectroscopy, MP-AES) analysis for crude oil samples. Nitrogen gas produced from air through a gas generator, and in combination with an external gas control module (EGCM) used to introduce air into the plasma, leads to a stable robust microwave-induced plasma, enough to perform the analysis of crude oil samples with different API values, sulfur (0.5–5 wt %) and nitrogen (500 −2500 mg/kg) by direct dilution in a o-xylene diluent. Excellent detection limits and spike recoveries at low and high concentration levels were determined for Ni, V, Fe, Ca, and Na in crude oil matrix. The recoveries obtained from the analysis of the three quality control (QC) test materials were within ±10% of the actual/certified values. Comparable results for Ni and V as well as the V/(V + Ni) ratio in crude oils between nitrogen pl...

Determination of sulfur in crude oil using high-resolution continuum source molecular absorption spectrometry of the SnS molecule in a graphite furnace

An analytical method for the determination of sulfur, as the tin mono-sulfide (SnS) molecule, in crude oil using high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS GF MAS) has been developed. The molecular absorbance of the SnS has been measured using the wavelength at 271.624nm and the crude oil samples were prepared as micro-emulsions due to their high viscosity. Several chemical modifiers (Ir, Pd, Ru, Zr) were tested and palladium was chosen, because it exhibited the best performance. The heating program was optimized by comparing the pyrolysis and vaporization curves obtained for an aqueous sulfur standard and a micro-emulsion of a crude oil certified reference material (CRM). The optimum pyrolysis and vaporization temperatures were found to be 600 and 2000°C, respectively. The limit of detection and the characteristic mass using micro-emulsion analysis of crude oil samples were 5.8 and 13.3ng S. Accuracy and precision of the method has been evaluated using two crude oil CRM (NIST 2721 and NIST 2722), showing good agreement with the informed or certified values.

Laser Induced Breakdown Spectroscopy Applied to Elemental Analysis Using Samples of Crude Oil from Adaril Oilfield

Aim: In this work Laser Induced Breakdown Spectroscopy (LIBS) has been used to identify the constituents of certain type of Sudanese crude oil. Study Design: This study was designed to use LIBS technique to analyze the emission spectral lines and to evaluate this technique in identifying the constituents of certain type of Sudanese crude oil. Place and Duration of Study: Department of laser system, institute of laser in Sudan university of Science and Technology – Republic of the Sudan and department of analytical chemistry, Malaga University – Spain, between June 2011 and July 2012. Methodology: Q-switched Nd: YAG laser was used to irradiate the samples and produce its plasma. The emission spectra of the plasma were collected via optical fiber and analyzed by a miniature Czerny–Turner spectrograph attached to CCD camera. Samples: Three crude oil samples collected from, Adaril Oilfield in south of Sudan were included in this work. Results: Characteristics elements in this crude oil, such as C, H, N, O, Ca, and Na were detected. The use of intensity ratios of the emission lines and bands in the samples allowed better characterization of the samples than the simple use of peak intensities. Conclusions: The analysis of crude oil samples led to efficient detection of different Research Article British Journal of Applied Science & Technology, 3(4): 916-924, 2013 917 constituents in these samples. Using LIBS technique in the oil industry can make a real addition because of its countless benefits, (e.g. real time, precision, sensitivity, selectivity and high speed).

Use of biomarkers, porphyrins, and trace elements to assess the origin, maturity, biodegradation, and migration of Alturitas oils in Venezuela

This work is an analysis of crude oil samples from thirty wells in the Alturitas Field (Lake Maracaibo Basin, western Venezuela). Different biomarkers, ten trace elements, and porphyrins were analysed using GC–MS, ICP–OES and UV–visible techniques, respectively. The characterization of these crude oils leads us to conclude that they all fall into a single non-biodegraded oil family derived from a single pulse of hydrocarbon generation, migration and accumulation from the thermally mature calcareous La Luna source rock deposited in an anoxic marine palaeoenvironment under reducing conditions. The main objective of this work is to present a secondary oil migration model for the Marcelina reservoir of the Alturitas Field. The multivariate statistical study of trace-element concentrations, porphyrin contents, and polar compound proportions shows that these parameters can be split into two groups. The first group (Cd, Cu, Mo, Fe, P, Zn, Ca, and Mg) indicates a chalcophic association (Cd, Cu, Mo, and Zn) or colloidal complexes with naphthenic acids (Ca, Mg, and Fe). The other two trace elements (V and Ni), together with porphyrins and polar compounds, reveal that oil compositions has been affected by geochromatography, indicating a highly probable secondary migration pathway along a preferential axis orientated southeast to northwest.

Atmospheric pressure laser ionization (APLI) coupled with Fourier transform ion cyclotron resonance mass spectrometry applied to petroleum samples analysis: comparison with electrospray ionization and atmospheric pressure photoionization methods

The analysis of crude oil samples remains a tough challenge due to the complexity of the matrix and the broad range of physical and chemical properties of the various individual compounds present. In this work, atmospheric pressure laser ionization (APLI) is utilized as a complementary tool to other ionization techniques for crude oil analysis. Mass spectra obtained with electrospray ionization (ESI) and atmospheric pressure photoionization (APPI) are compared. APLI is primarily sensitive towards non-polar aromatic hydrocarbons, which are generally present in high amounts especially in heavy crude oil samples. The ionization mechanisms of APLI vs. APPI are further investigated. The results indicate the advantages of APLI over established methods like ESI and APPI. The application of APLI in combination with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) is thus demonstrated to be a powerful tool for the analysis of aromatic species in complex crude oil fractions.

Comparative study of crude oils from the Machete area in the Eastern Venezuelan Basin by pyrolysis of asphaltenes

This work is an analysis of crude oil samples from the two most recent producing wells in the Machete area (Orinoco Tar Belt, Venezuela). The aim is to determine the type of environment in which the precursor organic materials were deposited. In spite of the fact that the degree of maturity and the biodegradation of the two crude oils are similar, their characterization leads us to conclude that they have very distinctive and different origins. The comparative study was performed by separating their main fractions, pyrolysis of asphaltenes, and further identification of several indicators (aromatic, polar and sulfur compounds, linear aliphatic hydrocarbons, and cadalene). Moreover, several biomarkers (terpanes, hopanoids and steranes) present in the saturated fractions obtained from the two crude oils were analyzed by using gas chromatography combined with mass spectrometry (GC–MS). The statistical study of geochemical indicator values and relative proportions of lipid and lipid-like biomarkers present in products from asphaltene pyrolysis shows a high probability of there being two distinct crude oil families from the Machete area.

Determination of the nature of naphthenic acids present in crude oils using nanospray Fourier transform ion cyclotron resonance mass spectrometry: the continued battle against corrosion.

Recent research has shown that the corrosivity of naphthenic acids is related to their molecular mass and that the "total acid number" (TAN), traditionally used as an indicator of the naphthenic acid content of an oil, is not as reliable as first believed. The presence of naphthenic acids in crude oils leads to the corrosion of oil refinery equipment, with the oil industry incurring costs that will ultimately be passed on to the consumer. With regard to these concerns, mass spectrometry has been increasingly applied to the investigation of the naphthenic acid content of crude oils. To ascertain the nature of the species present, however, it is necessary to utilize an ionization technique that does not result in fragmentation, ensuring the detection only of molecular species which provide useful information about the sample constitution. In the following investigation, negative ion mode nanospray Fourier transform ion cyclotron resonance (FTICR) mass spectrometry has been applied to the analysis of crude oil samples, providing insight into the different acidic species that were present. Use of the negative ion mode to allow the selective observation of the naphthenic acids and the inherent high mass accuracy and ultrahigh resolution of FTICR mass spectrometry ensure that this technique is very well suited to the characterization of naphthenic acids within a crude oil sample. Determination of the nature of the naphthenic acids present provides vital information, such as the acids' sizes and composition, which may be used in the battle against corrosion and also used to fingerprint samples from different oil fields.

Multi-element analysis of crude-oil samples by 14.6 MeV neutron activation

The instrumental neutron activation technique, using the SAMES T-400 neutron generator with 14.6 MeV neutrons produced from3H(d,n)4He reaction is demonstrated for multi-element analysis of Saudi-Arabian crude-oil samples. The system parameters for the absolute method (e.g., the counting solid-angle, intrinsic efficiency of the γ-ray detector, effective neutron flux, activation cross sections, etc.) were determined and the results of elemental concentrations were presented with the corrections for all possible interferences having been carefully considered.