Recent Advances in the Detection of Sulfur Compounds in Crude Oil and Petroleum Products

Application of liquid-phase microextraction for the determination of sulfur compounds in crude oil and diesel

This article reports on a study of the distribution of organic sulfur compounds (mercaptans, disulfides, and sulfides) in crude oils and in 50/sup 0/C cuts, and also in gas condensates. Notes that the crude oils of West Kazakhstan, particularly the field that have been discovered recently, are extremely diverse in physiochemical properties, particularly in their content and structure of organic sulfur compounds. The oils from the Tortai, Kultuk and Zhilankabak fields are classified as low-sulfur (total sulfur contents 0.22%, 0.44%, and 0.47%, respectively). Investigates the group composition of condensates from the Gremyachinsk, East Gremyachinsk, West Teplovsk, and Karachaganak fields are also investigated.

6 - Polycyclic aromatic sulfur heterocycles as source diagnostics of petroleum pollutants in the marine environment

One of the most important problems in the oil industry is the presence of sulfur and sulfur compounds in crude oil. Sulfur compounds in crude oil can have detrimental effects on the environment, equipment, catalysts, and end products. One of the most important goals of researchers in recent years is to sweeten petroleum products from these compounds. This study aims to use NiWO4/W5O14/WO3 composite nanostructure to solve this problem using the photocatalytic oxidative desulfurization method. This composite nanostructure has been synthesized by Pechini sol-gel method with high purity at low temperature and examined by XRD, EDS, FESEM, and FT-IR analysis. Due to the presence of WO3 in the composition, the bandgap was greatly reduced and the efficiency was increased. As a result, the nanostructure could degrade more than 73% of the sulfur in thiophene in 180 min under visible light. By optimizing the amount of photocatalyst and irradiation time, the efficiency can be improved.

Demercaptanization of sulfur compounds in crude oil in the presence of metal complex oxidation catalysts was studied. The adsorption capacities of the catalysts and industrial mercaptane scavengers were compared. The possibility of using these catalysts for the removal of light sulfur impurities in the field oil preparation was shown.

The composition and structure of sulfur compounds in low-, medium-, and high-sulfur crude oils from the Jurassic-Paleozoic play of Western Siberia have been studied. It has been shown that the distribution of organic sulfur compounds in the oils is determined by the depositional environment of source organic matter. Highly alkylated dibenzothiophenes (up to 15 carbon atoms in the aliphatic chain), naphthobenzothiophene isomers and their C1 and C2 homologues, and the α-n-alkylthiolane and α-n-alkylthiane homologous series have been identified for the first time among sulfur compounds of Western Siberia crude oils.

The existence of sulfur compounds in crude oils creates many problems of sulfur deposition in the vicinity of wellbore hole, in well completion and/or production equipment, and in producing reservoir rocks. The major objectives of this experimental study are to investigate the influences of oil flow rate, initial sulfur concentration of crude oil, and reservoir rock permeability on elemental sulfur plugging in carbonate oil reservoirs. To achieve these objectives, actual crude oils were de-asphaltened to eliminate the effect of asphaltene deposition. Ten dynamic flow experiments were conducted using two actual crude oils of 0.78 % and 1.67 % sulfur concentrations. Viscosity of crude oils of different sulfur concentrations was measured under different conditions of temperature. The crude oils were flooded through actual carbonate cores of different permeability in the range of 2.34 to 28.16 millidarcy and under different flow rates of 0.5, 1.0, 1.5, and 2.0 cc/min. In-situ sulfur deposited was measured using Scanning Electron Microscope (SEM) to provide the amount of sulfur deposited along the core samples. The results indicated that crude oil of higher sulfur concentration has higher viscosity than that one of lower concentration. The deposition of elemental sulfur does not take place at low rate of 0.50 cc/min, starts at 1.0 cc/min and increases as the flow rate increases up to 1.50 and 2.00 cc/min, respectively. In addition, the higher of sulfur concentration of the crude oil increases the deposition of sulfur in carbonate oil reservoirs. The results also showed that permeability of carbonate reservoir rocks has a severe effect on sulfur deposition since carbonate rocks of higher permeability does not experience the problem of elemental sulfur deposition while the problem is more severe for lower permeability rocks. In addition, the depositional rate is accelerated rapidly as the rock permeability decreases. The obtained results of this study have important interest in identification the most important factors affecting the elemental sulfur precipitation in heterogeneous carbonate oil reservoirs and robust implications in the development of reservoir simulation models. INTRODUCTION AND REVIEW Many gas/oil reservoirs suffer of having large amounts of hydrogen sulfide and other sulfur compounds. Sulfur occurs free in the elemental state. Precipitation of elemental sulfur within reservoir rocks can impair oil productivity and thus affects economic feasibility negatively. Sulfur compounds are considered as the most important non-hydrocarbons in crude oils, because of (1) their corrosive nature, (2) their deleterious effects of petroleum products, (3) their attendance to plug porous medium, which may impair formation productivity, (4) their effect on oxidation characteristics, and (5) their disagreeable odor.

Through proof-of-concept experiments, a preliminary structural characterization of isomeric and isobaric sulfur-containing compounds in petroleum is presented. Silver attachment to sulfur atom has been used for ionization enhancement of these compounds, which are less accessible by positive-ion electrospray ionization mass spectrometry (ESI-MS). Here, ion mobility spectrometry (IMS) is combined with the enhanced ionization approach and MS to characterize sulfur compounds in crude oil. The silver isotopes, being of nearly equal abundance and having a similar effect upon ion mobilities, provide a fingerprint for assignments of sulfur-containing ions in two-dimensional (2D) plots of mass-to-charge (m/z) vs drift time (tD). Fourier transform ion cyclotron resonance (FT-ICR) MS has been employed for the determination of molecular formulas for these ions. Collision-induced dissociation (CID) data are utilized to complement collision cross section (CCS) comparisons for candidate structures obtained from high mas...

Estimating the concentration of sulphur compounds in crude oil and its products such as gasoline and kerosene is necessary because of environmental legislation and determinants developed by government organizations regulating sulphur levels in oil and its derivatives. Sulphur compounds found in crude oil and its products are a major problem, causing many environmental and health risks as a result of the use of gasoline as fuel for cars and kerosene as fuel for household heaters, resulting in the emission of these compounds in the form of oxides, affecting the environment and health. This study was conducted to estimate the concentration of sulphur compounds in crude oil and distillation products represented by gasoline and kerosene and to show how different the concentration of sulphur compounds in crude oil is than in gasoline and kerosene. In this study, gas chromatography technology was used. This method applies to distillation products, gasoline fuel, kerosene and other petroleum liquids. This study was conducted in basra oil company's quality control laboratories to estimate the concentration of sulphur compounds in crude oil, gasoline and kerosene.

Recent Advances in the Chemistry of Benzo[b]thiophenes

The determination of water content in crude oil is important for oil transportation, refining, and trade. However, the sensitivity and accuracy of the conventional azeotropic distillation (AD) method are inadequate. Karl Fischer titration methods may give false high results because of the reducing sulfur compounds in crude oil. The present study developed an azeotropic distillation Karl Fischer coulometric titration (AD-KFCT) method which required a modified instrument and a new calibration procedure. The method was modified to decrease the interference caused by reducing sulfur compounds. A certified reference material for water content in liquid was used to determine the recovery of water mass achieved using the AD-KFCT method. The effect of the sample polarity on the method accuracy was assessed. The relative error and relative standard deviations of the water content in three crude oils containing known amounts of water were -7.5% to 2.9% and 0.4% to 6.0%, respectively. The interference by reducing sulfur compounds was studied. The crude oil containing 1-propanethiol was measured using a sulfur dioxide-free anolyte, and the amount of iodine consumed by the distilled 1-propanethiol was determined. The contribution of 1-propanethiol was then subtracted from the water content measured using the normal Karl Fischer reagent. Finally, the relative error of the modified water content in the crude oil samples containing 1-propanethiol was -4.4% to 0.7%. Therefore, the modified AD-KFCT method is accurate and convenient for crude oil.

The existence of sulfur compounds in crude oils creates many problems of sulfur deposition in the vicinity of the wellbore hole, in well completion and/or production equipment, and in producing reservoir rocks. The major objectives of this experimental study are to investigate the influences of oil flow rate, initial sulfur concentration of crude oil, and reservoir rock permeability on elemental sulfur plugging in carbonate oil reservoirs. To achieve these objectives, actual crude oils were de-asphaltened to eliminate the effect of asphaltene deposition. Ten dynamic flow experiments were conducted using two actual crude oils of 0.78 and 1.67% sulfur concentrations. Viscosity of crude oils of different sulfur concentrations was measured under different conditions of temperature. The crude oils were flooded through actual carbonate cores of different permeability in the range of 2.34–28.16 millidarcy and under different flow rates of 0.5, 1.0, 1.5, and 2.0 cc/min. In-situ sulfur deposited was measured using Scanning Electron Microscopy (SEM) to provide the amount of sulfur deposited along the core samples. The results indicated that crude oil of higher sulfur concentration has higher viscosity than that of one of lower concentration. The deposition of elemental sulfur does not take place at the low rate of 0.50 cc/min, starts at 1.0 cc/min and increases as the flow rate increases up to 1.50 and 2.00 cc/min, respectively. In addition, the higher sulfur concentration of the crude oil increases the deposition of sulfur in carbonate oil reservoirs. The results also showed that permeability of carbonate reservoir rocks has a severe effect on sulfur deposition since carbonate rocks of higher permeability do not experience the problem of elemental sulfur deposition while the problem is more severe for lower permeability rocks. In addition, the depositional rate is accelerated rapidly as the rock permeability decreases. The obtained results of this study have important interest in identification of the most important factors affecting the elemental sulfur precipitation in heterogeneous carbonate oil reservoirs and robust implications in the development of reservoir simulation models.

Water separation from crude oil inside oil transport pipelines causes the water to wet the inner steel surface of the pipe and leads to corrosion and leaks. Factors that affect the water settlement inside pipelines, interchangeably called as water-wetting phenomenon, are major areas of research. Previous studies focused on the physical properties of crude such as density, viscosity, interfacial tension and water-in-oil contact angle as factors affecting water wetting. In those studies, alteration of physical properties toward preventing water wetting inside crude pipelines was attributed to the presence of surface-active compounds in the crude oils, which promotes smaller water droplets, oil adsorption to the steel surface thus oil wetting; this was concluded through artificial mixing of selected surface active compounds with model oils. In the current paper, we will determine whether the natural presence of surface-active compounds in crude oils can only explain the alteration of the steel wettability of actual oils or not. To achieve that, a water-wetting study is conducted on a model oil blend mixture with 1% myristic acid, a carboxylic acid surface-active compounds, which mimics the PNA distribution and physical properties of an actual type of crude oil produced from a certain field. Using a doughnut cell wetting measurement apparatus, it was found that the model oil blend mixture with the myristic acid has reduced water wetting transition velocity by 60% compared to that of an actual crude of the similar physical properties. This indicates that the crude composition might have a higher impact on the water-wetting phenomena regardless of the natural presence of the surface-active compounds in the crude oil. Introduction Crude oil transport pipelines experience a significant increase in pipeline damage due to internal corrosion as oil fields mature. It is not coincidental that frequency of internal corrosion damage increases as the water-cut in the throughput continues to increase. In such situations, oil transport pipelines become oversized due to the low production rates which reduces the liquid velocities and allows free water to separate from the oil, thereby aggravating the corrosion environment in the pipeline. Previous experiments were conducted and predication models were developed to calculate the velocities below which water dropout occurs. In these models, water wetting transition velocity is dependent on physical properties of the fluid that includes fluid density, viscosity, oil-water interfacial tension, pipe diameter (Hinze 1955, Brauner 2001 and Tang 2011) and water-in-oil contact angle (Tang 2011). According to these models, oil wetting is promoted by higher density, higher viscosity, lower interfacial tension and larger water-in-oil contact angle. Compared to actual crude oils, model oils have higher tendency toward water wetting, which was attributed to the natural presence of surface-active compounds in crude oils (Ayello 2013). The adsorption of surface-active compounds at the metal surface can create an organic protective film and its presence in the oil-water interface reduces the oil-water interfacial tension, which prevents water droplets from wetting the steel surface (Ayello 2013).

Owing to the environmental hazards arising from sulfur-containing combustion products, strong legal regulations exist to reduce the sulfur content of transportation fuels down to a few ppm. With the ongoing depletion of low-sulfur crude oil reservoirs, increased technological efforts are needed for crude oil refining to meet these requirements. The desulfurization step is a critical part of the refining process but partly suffers from the recalcitrance of certain species to sulfur removal and the inability to quantitatively understand the behavior of individual compound classes during the process. We herein present a new and simple approach for the parallel quantification of three different classes of sulfur species present in crude oils by LC separation and on-line detection and quantification by ICP-MS/MS. This approach will help to estimate the amount of recalcitrant species and thus facilitate the optimization of desulfurization conditions during fuel production.

SummaryThe subsurface microbiology of an Athabasca oil sands reservoir in western Canada containing severely biodegraded oil was investigated by combining 16S rRNA gene- and polar lipid-based analyses of reservoir formation water with geochemical analyses of the crude oil and formation water. Biomass was filtered from formation water, DNA was extracted using two different methods, and 16S rRNA gene fragments were amplified with several different primer pairs prior to cloning and sequencing or community fingerprinting by denaturing gradient gel electrophoresis (DGGE). Similar results were obtained irrespective of the DNA extraction method or primers used. Archaeal libraries were dominated by Methanomicrobiales (410 of 414 total sequences formed a dominant phylotype affiliated with a Methanoregula sp.), consistent with the proposed dominant role of CO2-reducing methanogens in crude oil biodegradation. In two bacterial 16S rRNA clone libraries generated with different primer pairs, > 99% and 100% of the sequences were affiliated with Epsilonproteobacteria (n = 382 and 72 total clones respectively). This massive dominance of Epsilonproteobacteria sequences was again obtained in a third library (99% of sequences; n = 96 clones) using a third universal bacterial primer pair (inosine-341f and 1492r). Sequencing of bands from DGGE profiles and intact polar lipid analyses were in accordance with the bacterial clone library results. Epsilonproteobacterial OTUs were affiliated with Sulfuricurvum, Arcobacter and Sulfurospirillum spp. detected in other oil field habitats. The dominant organism revealed by the bacterial libraries (87% of all sequences) is a close relative of Sulfuricurvum kujiense – an organism capable of oxidizing reduced sulfur compounds in crude oil. Geochemical analysis of organic extracts from bitumen at different reservoir depths down to the oil water transition zone of these oil sands indicated active biodegradation of dibenzothiophenes, and stable sulfur isotope ratios for elemental sulfur and sulfate in formation waters were indicative of anaerobic oxidation of sulfur compounds. Microbial desulfurization of crude oil may be an important metabolism for Epsilonproteobacteria indigenous to oil reservoirs with elevated sulfur content and may explain their prevalence in formation waters from highly biodegraded petroleum systems.