Real Crude Oil Research Articles

Measuring Fluid Level through a Recalibrating-Free Hough Transform Methodology

Fluid level monitoring is an important control process in engineering systems. The level measurement of fluids having changeable densities is a complex task. Most measurement methodologies use sensors that are periodically paused for recalibrations. For flammable liquids, this may be unsafe and even dangerous. This paper proposes a safe recalibrating-free computer-based methodology for measurement of fluid levels, which is based on Hough transform, image processing and normalization. This paper also describes experiments using a prototype of a distillation unit that was built especially to test the proposed methodology. The results from these experiments have demonstrated robustness, low-cost and suitability of the methodology for real crude oil level measurement in distillation processes.

Effect of Premixed Asphaltenes and Demulsifier on Oil-Water Interfacial Properties

During crude oil recovery, asphaltene-stabilized water-in-oil emulsions are formed. Asphaltenes is the component of crude oil, which is insoluble in n-alkane and is considered to be largely responsible for the stability of water-in-crude oil emulsions. To avoid wide range of problems, water has to be removed from these emulsions by using chemical ‘demulsifiers’. How demulsifiers act is still poorly understood. As the real crude oil system is extremely complex, system consisting of model oil with 100 ppm asphaltenes concentration is used as this concentration corresponds to nanoaggregation in the bulk fluid as shown in previous work. The surface pressure values appear to be a result of both asphaltenes and demulsifier competing to adsorb at the interface. The fractional interfacial coverage achieved by each appears to depend on their respective bulk concentrations. Thus demulsifier-asphaltene systems exhibit an equilibrium surface pressure, reached at higher demulsifier concentrations possibly due to adsorption balancing desorption in the demulsifier rich regions, the presence of which block the ‘almost insoluble’ asphaltenes from further coverage of interface. The behavior of the surface pressure on expansion and contraction of droplets using pendant drop to emulate a Langmuir trough supports the notion of concentration-dependent fractional coverage by each species.

Indirect Method: A Novel Technique for Experimental Determination of Asphaltene Precipitation

Asphaltenes represent one of the major potential flow assurance problems in the upstream oil industry. Asphaltene precipitation determination is a key step in studying the asphaltene deposition problems because precipitation is a necessary condition for the asphaltenes to deposit. In this work, a novel experimental technique called the “indirect method” is used for studying asphaltene precipitation on both model oil and real crude oil systems. This method, which is a combination of gravimetric and spectroscopic techniques, is proposed for the detection and quantification of asphaltene precipitation in dead oil samples. The term “indirect” refers to an indirect detection of the precipitation of asphaltenes, by measuring the absorbance of the supernatant fluid after centrifugation of oil/n-alkane mixtures. The results obtained in this study show that the indirect method has three main advantages over direct methods. First, it can be applied to detect asphaltene precipitation and also to quantify the amount ...

Understanding recent oil price dynamics: A novel empirical approach

Crude oil is a major driver of the global economy and its price dynamics are a key indicator for producers, consumers and investors. The increasing volatility of crude oil prices in the last decade has encouraged many researchers to model its dynamics. Recent studies have tried to explain this dynamics by taking into account the role of various market participants many of whom have increasingly used crude oil for portfolio diversification. We propose a modified supply–demand framework which assumes that the real price of crude oil is affected not only by fundamental shocks but also by financial shocks. We assess the role of what we define as the financial shock component when describing the dynamics of the real crude oil price and endeavor to measure a possible equilibrium relationship between standard supply/demand variables and our financial shock component. Using a Dynamic Ordinary Least Squares (DOLS) approach and an ECM framework we are able to empirically assess the significant role of “hedging pressure” on the real price of oil and find evidence that the impact of the “hedging pressure” is not only affecting quick reverting short-term deviations but also the structural long-run equilibrium of the oil price.

In Situ Electron Spin Resonance Study of Molecular Dynamics of Asphaltenes at Elevated Temperature and Pressure

A comparison of the behavior of asphaltene molecules extracted from crude oil and dissolved in aromatic solvent as a model system with the behavior of vanadium-containing molecules in real crude oils via electron spin resonance in situ technique showed that the changes of rotational mobility of asphaltene molecules can be related to the changes of the local viscosity and environment of the asphaltenes as well as the characteristic sizes of vanadyl-containing fragments because of aggregation/disaggregation processes in crude oils. The information about the mobility of asphaltene molecules in different local environments at different temperatures and pressures is an important step in understanding both the aggregation of the asphaltenes and crude oil fouling processes in addition to the conditions required for the deposits to be formed.

Catalytic Neutralization Method for Naphthenic Acid Removal in Crude Oil by Alumina Supported Ca and Ba Catalysts

The presence of naphthenic acids in crude oils has caused a major corrosion problem to the production equipment, storage and transport facilities in the petroleum industry. To overcome this problem, catalytic neutralization method will be investigated on real petroleum crude oil sample with various parameters study such as the type of basic chemical used, dosing amount, type of catalyst, catalyst calcination temperature, and catalyst ratio of basic metal and dopant. Potential catalyst was characterized by XRD, NA, and TGA-DTA for its physical properties. Cu/Ca(10:90)/Al2O3 catalyst with calcination temperature of 1000°C was an effective catalyst for all three types of crude oil. In the presence of catalyst, all three types of crude oil samples showed enhancement in the removal of naphthenic acid.

Speculative bubbles in agricultural prices

Abstract We use the momentum threshold autoregressive (MTAR) approach to test for speculative bubbles in US corn, soybean and wheat prices. To approximate fundamental values of these agricultural commodities, we use real crude oil prices and real exchange rates. Our empirical results support the hypothesis that speculative bubbles are present in wheat prices between 2003 and 2013. For corn and soybeans, however, our empirical results are inconclusive.

Cold Vapor Atomic Absorption Determination of Hg in Crude Oil and Gasoline Samples after Solid Phase Extraction Using Modified Disks

A facile and highly efficient method have been developed for the preconcentration of the mercury content in crude oil and gasoline samples after digestion with microwave-assisted digestion. Octadecyl silica membrane disk has been modified by the recently synthesized triazene ligand, (E)-1-(2-ethoxyphenyl)-3-(4-nitrophenyl) triaz-1-ene (ENT), then the modified membrane was used for the preconcentration of mercury(II) ions and Cold Vapor Atomic Absorption Spectrometry (CV-AAS) have been used to determine the Hg (II) ion. Solution studies of ENT with a series of metal ions have been done in advance, and the results showed a strong affinity of ENT to the mercury ion. For solid phase extraction, pH of sample 6.0, flow rates 3.0 mL / min, enrichment factor 240, capacity of modified disk 690 µg Hg per 8.0 mg of ligand, eluent solvent 5.0 mL, 1.5M HClO 4, and the amount of the ligand 8.0 - 10.0 mg, have been optimized. A linear calibration curve has been obtained in the range of 0.80 - 65 µg / L with R 2 = 0.9991 and the Limit Of Detection (LOD) based on three times the standard deviation of the blank was 0.25 µg / L. The Relative Standard Deviation (RSD) for the determination of 50 mL aqueous solution containing 0.5 µg / L Hg (II) found to be 1.0 % while a RSD value of 1.9% have been obtained for the determination of 0.1 µg / L Hg (II) (n=3). The characteristic concentration is 1.2 µg / L in the original samples. The newly developed method was successfully applied to the determination of mercury ion in real crude oil samples, which are very important in environment and industries process.

FORECASTING CRUDE OIL PRICE MOVEMENTS WITH OIL‐SENSITIVE STOCKS

This paper uses monthly data from 1984:M10 to 2012:M8 to show that oil‐sensitive stock price indices, particularly those in the energy sector, have strong power in predicting nominal and real crude oil prices at short horizons (1‐month‐ahead predictions), using both in‐ and out‐of‐sample tests. In particular, the forecasts based on oil‐sensitive stock price indices are able to outperform significantly the no‐change forecasts. For example, using the NYSE Arca (AMEX) oil index as a predictor, the 1‐month‐ahead forecasts for nominal crude oil prices reduce the mean squared prediction error by between 22% (for the West Texas Intermediate oil price) and 28% (for the Dubai oil price). Moreover, we find that the directional forecast based on the AMEX oil index is significantly better than a 50:50 coin toss. The novelty of this analysis is that it proposes a new and valuable predictor that both reflects timely market information and is readily available for forecasting the spot oil price.(JEL G17, Q43, Q47, C53)

Thermal behavior and solid fraction dependent gel strength model of waxy oils

Thermal behavior of waxy oils is investigated using the techniques of thermogravimetric (TG) analysis and differential scanning calorimetry (DSC). Model waxy oils and real waxy crude oils are utilized. Decomposition temperatures of waxy oils are obtained using TG analysis. The effects of thermal history, wax content, and additive on the gelation process of waxy oils are investigated using DSC. The DSC method provides a measure of wax solubility as well as solid fraction. An integration method and a computation method are utilized to predict solid fraction. In addition, wax crystallization onset points are obtained at the cooling rates ranging from 1 to 20 °C min−1. Similarly, wax dissolution endset points are obtained at heating rates ranging from 1 to 20 °C min−1. Extrapolated onset and endset points yield wax precipitation temperature and wax dissolution temperature, respectively. Subsequently, wax solubility curves are obtained using thermodynamic computations. A wax precipitation temperature method and a wax dissolution temperature method combine thermodynamic phase behavior with onset/endset points to predict solid fraction. Both the wax precipitation temperature method and the wax dissolution temperature method can predict solid fraction of waxy oil samples. The wax precipitation temperature method and the wax dissolution temperature method are accurate when the temperature is close to the wax appearance temperature. A heat-integration method provides accurate values of the solid fraction at temperatures significantly below the wax appearance temperature. Therefore, integration method and wax precipitation temperature/wax dissolution temperature method are combined to predict solid fraction. The effect of solid fraction on yield stress is also investigated using differential scanning calorimetry and rheometry. Finally, a new solid fraction dependent gel strength model is obtained for shut in and restart of waxy crude oil pipelines.

Preparation of Multiwalled Carbon Nanotubes/Hydroxyl-Terminated Silicone Oil Fiber and Its Application to Analysis of Crude Oils

A simple and efficient method to analyze the volatile and semivolatile organic compounds in crude oils has been developed based on direct immersion solid-phase microextraction coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (DI-SPME-GC × GC/TOFMS). A novel fiber, multiwalled carbon nanotubes/hydroxyl-terminated silicone oil (MWNTs-TSO-OH), was prepared by sol-gel technology. Using standard solutions, the extraction conditions were optimized such as extraction mode, extraction temperature, extraction time, and salts effect. With the optimized conditions, a real crude oil sample was extracted and then analyzed in detail. It shows that the proposed method is very effective in simultaneously analyzing the normal and branched alkanes, cycloalkanes, aromatic hydrocarbons, and biomarkers of crude oil such as steranes and terpanes. Furthermore, the method showed good linearity (r > 0.999), precision (RSD < 8%), and detection limits ranging from 0.2 to 1.6 ng/L.

Characterization of compounds in crude oils by gas purge micro-syringe extraction coupled to comprehensive two-dimensional gas chromatography

A novel sample pretreatment method, gas purge micro-syringe extraction (GP- MSE), coupled to comprehensive two-dimensional gas chromatography/time-of-flight mass spectrometry (GC x GC/TOFMS) has been developed for the characterization of volatile and semi-volatile compounds in crude oils. In the sample pretreatment process, the analytes were carried to the microsyringe barrel by inert gas, and at the same time, trapped by an organic solvent. The whole process of extraction takes less than 10 min, and only 20 μL of organic solvent was needed. Using two custom standard solutions containing alkanes and polycyclic aromatic hydrocarbons (PAHs), the influences of the extraction conditions were investigated. The optimized conditions were as follows: 5 mg crude oil, 20 μL hexane (extraction solvent), extraction for 3 min at 300 °C, condensation temperature set at -2 °C, gas flow rate set at 2 mL/min. Under the optimized conditions, a real crude oil sample was extracted and then analyzed in detail. It showed that the proposed method was very effective in simultaneously analyzing the normal and branched alkanes, cycloalkanes, aromatic hydrocarbons, and biomarkers of crude oil such as steranes and terpanes. The recoveries obtained ranged from 82.0% to 107.3% and the detection limits ranged from 34 to 93 μg/L. The correlation coefficients (R2) were more than 0.99. The relative standard deviations (RSDs, n = 5) for all the analytes were below 10%. The results indicate that the proposed method is suitable for the characterization of volatile and semi-volatile compounds in crude oils with easy operation, high sensitivity and efficiency.

Experimental and modeling study of the phase behavior of synthetic crude oil + CO2

A full understanding of the phase behavior of CO2–hydrocarbon mixtures at reservoir conditions is essential for the proper design, construction and operation of carbon capture and storage (CCS) and enhanced oil recovery (EOR) processes. While equilibrium data for binary CO2–hydrocarbon mixtures are plentiful, equilibrium data and validated equations of state having reasonable predictive capability for multi-component CO2–hydrocarbon mixtures are limited. In this work, a new synthetic apparatus was constructed to measure the phase behavior of systems containing CO2 and multicomponent hydrocarbons at reservoir temperatures and pressures. The apparatus consisted of a thermostated variable-volume view cell driven by a computer-controlled servo motor system, and equipped with a sapphire window for visual observation. Two calibrated syringe pumps were used for quantitative fluid injection. The maximum operating pressure and temperature were 40MPa and 473.15K, respectively. The apparatus was validated by means of isothermal vapor–liquid equilibrium measurement on (CO2+heptane), the results of which were found to be in good agreement with literature data.In this work, we report experimental measurements of the phase behavior and density of (CO2+synthetic crude oil) mixtures. The ‘dead’ oil contained a total of 17 components including alkanes, branched-alkanes, cyclo-alkanes, and aromatics. Solution gas (0.81 methane+0.13 ethane+0.06 propane) was added to obtain live synthetic crudes with gas-oil ratios of either 58 or 160. Phase equilibrium and density measurements are reported for the ‘dead’ oil and the two ‘live’ oils under the addition of CO2. The measurements were carried out at temperatures of 298.15, 323.15, 373.15 and 423.15K and at pressures up to 36MPa, and included vapor–liquid, liquid–liquid and vapor–liquid–liquid equilibrium conditions. The results are qualitatively similar to published data for mixtures of CO2 with both real crude oils or and simple hydrocarbon mixtures containing both light and heavy components. The present experimental data have been compared with results calculated with two predictive models, PPR78 and PR2SRK, based on the Peng–Robinson 78 (PR78) and Soave–Redlich–Kwong (SRK) equations of state with group-contribution formulae for the binary interaction parameters. Careful attention was paid to the critical constants and acentric factor of high molar-mass components. Since the mixture also contained several light substances with critical temperatures below some or all experimental temperatures, we investigated the use of the Boston–Mathias modification of the PR78 and SRK equations. The results showed that these models can predict with reasonable accuracy the vapor–liquid equilibria of systems containing CO2 and complex hydrocarbon mixtures without the need to regress multiple binary parameters against experimental data.

Asphaltene Deposition in Different Depositing Environments: Part 1. Model Oil

Among the asphaltene flow assurance issues, the most major concern because of asphaltene is its potential to deposit in reservoir, well tubing, flow lines, separators, and other systems along production lines causing significant production losses. Hence, the focus of this study is to understand the depositional tendency of asphaltene using quartz crystal microbalance with dissipation (QCM–D) measurements. The results are presented in two consecutive papers, with this paper (part 1) dealing with model oil systems. The depositing environment is varied by changing the system temperature, asphaltene polydispersity, solvent (asphaltene stability), depositing surface, and flow rate. This paper also discusses the roles of convective, diffusive, and adsorption kinetics on asphaltene deposition by modeling the adsorbed mass before asphaltene precipitation onset. The successive paper (part 2; 10.1021/ef401868d) will deal with real crude oil systems and modeling of the deposited mass after asphaltene precipitation o...

Forecasting Crude Oil Price Movements with Oil-Sensitive Stocks

This paper uses monthly data from 1984:M10 to 2012:M8 to show that oil-sensitive stock price indices, particularly those in the energy sector, have strong power in predicting nominal and real crude oil prices at short horizons (one-month-ahead predictions), using both in- and out-of-sample tests. In particular, the forecasts based on oil-sensitive stock price indices are able to outperform significantly the no-change forecasts. For example, using the NYSE Arca (AMEX) oil index as a predictor, the one-month-ahead forecasts for nominal crude oil prices reduce the mean squared prediction error by between 22% (for the West Texas Intermediate oil price) and 28% (for the Dubai oil price). Moreover, we find that the directional forecast based the AMEX oil index is significantly better than a 50:50 coin toss. The novelty of this analysis is that it proposes a new and valuable predictor that both reflects timely market information and is readily available for forecasting the spot oil price.

Controlled Shear Stress and Controlled Shear Rate Nonoscillatory Rheological Methodologies for Gelation Point Determination

An experimental rheometric investigation is performed to assess the utility of various gelation point determination methodologies. Controlled shear stress and controlled shear rate methods are developed to investigate gelation processes in waxy oils. The nonoscillatory rheological method exhibits high reproducibility for model wax oils as well as for real crude oils. In addition, the nonoscillatory methods are in good agreement with standard oscillatory gel point determination methods. The effect of imposed shear stress, imposed shear rate, and cooling rate on gelation point is investigated with two types of model oils: 5 wt % macrocrystalline wax in Primol 352 and 5 wt % macrocrystalline wax in dodecane. In addition, the effect of wax content on gel temperature of macrocrystalline wax in dodecane is investigated. Moreover, the effect of additives (A3 and A4) on gelation point of a real crude oil UL-YS1 is investigated. Finally, the gelation temperatures of 5 wt % macrocrystalline wax in Primol 352, crude oil UL-YS1, and Se-7-E06 are investigated by three methods: constant imposed shear stress, constant imposed shear rate, and oscillatory G′–G″. Gel point results are obtained with the various protocols for real and model oil systems. The nonoscillatory rheological method is applicable for gel point determination of model wax oils as well as real crude oils. Hence, due to its high repeatability and instrumental accuracy, the nonoscillatory rheological method is a promising method for gel point determination.

Online estimation of wax deposition thickness in single-phase sub-sea pipelines based on acoustic chemometrics: A feasibility study

Wax deposition in sub-sea oil producing pipelines is a concern to the oil producing companies. The deposition of wax in pipelines can cause serious economic implications if not monitored and controlled. Several researchers have developed models and investigated the deposition of wax in crude oil pipelines. As of today, there is no off the shelf instrument available for reliable online estimation of the wax deposition thickness in sub-sea pipelines. Acoustic chemometrics was applied to investigate the potential for online estimation of wax deposition thickness in sub-sea pipelines. This feasibility study was carried out as a so called piggy back on experiments performed at Statoil research centre in Porsgrunn, Norway with real crude oil or waxy gas condensate. The first investigations focused on the repeatability of the acoustic chemometric technique followed by online prediction of the wax deposition thickness in a single-phase oil flow pipeline. A partial least squares regression model was calibrated and validated with a totally independent data set. The calibrated model had a root mean squared error of prediction of 0.28mm with a final wax deposition thickness of 3.36mm, a slope of 0.91 and R2 of 0.83 which were satisfactory results. The effect of varying oil flow rates on the wax deposition thickness was also investigated. The preliminary results showed the need for further investigations based on a robust experimental design and sample pre-processing. The general conclusion that can be drawn from this feasibility study was that the potential of adapting the acoustic chemometric technique for online estimation of the wax deposition thickness exist and must be further investigated.

Gelation Behavior of Model Wax–Oil and Crude Oil Systems and Yield Stress Model Development

An experimental investigation of waxy oil gelation behavior is performed using the methods of rheometry, optical analysis, tensiometry, and microscopy. Thermal history, shear history, asphaltene content, and chemical additives influence the gelation process. Consequently, the final gel state is strongly correlated to the gelation conditions. Various model wax–oil systems are prepared, including 5 wt % microcrystalline wax or 5 wt % macrocrystalline wax in dodecane, as well as 5 wt % macrocrystalline wax in Primol 352. Real waxy crude oils UL-YS1 and Se-7-E06 are also investigated. A new yield stress model is developed on the basis of experimental results and a modified Eyring theory to provide gel strength predictions for petroleum transport pipelines. In the absence of shear during gelation, the yield stress can be correlated with the thermal history. However, for non-quiescent gelation conditions, the gel strength is also dependent upon the imposed shear history during the gelation process. The imposed shearing influences the growth process of a volume-spanning crystal network. Finally, pressure wave propagation calculations are performed following the Rønningsen convention, highlighting the impact of yield stress on startup lag times associated with wax gelation in field transport pipelines.

Impact of Chemical Enhanced Oil Recovery on the Separation of Diluted Heavy Oil Emulsions

This study focuses on the potential impact of a chemical enhanced oil recovery (EOR) operation on the separation of diluted heavy oil emulsions. The main objective was to underline through experiments on a real crude oil the problems related to the formation of stable emulsions which may be difficult to break. We studied first the influence of alkaline, surfactant and polymer on the formation and separation of emulsions formed under gentle conditions of agitation. In a second step, we analyzed the impact of alkaline and surfactant on emulsification under strong shearing conditions as well as their impact on the efficiency of separation of water-in-crude oil emulsions by the main processes used on the production field, i.e., chemical demulsification and electrocoalescence.

Impacts of Macroeconomic Forces and External Shocks on Real Output for Indonesia

Abstract: Extending Romer (2000, 2006) and Taylor (1993, 1999, 2001), this paper applies the IS-MP model to study potential impacts of selected macroeconomic variables and external shocks including crude oil prices on real GDP for Indonesia. The results show that a higher real stock price, real appreciation of the rupiah, a lower inflation rate, a higher real crude oil price, and a lower real federal funds rate are expected to increase Indonesia’s real GDP. More deficit spending as a percent of GDP would not cause real output to rise. Hence, Indonesia would not suffer declining output because of higher oil prices. Due to the insignificant coefficient of the government deficit as a percent of GDP, fiscal prudence needs to be pursued.