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    Forecasting crude oil prices: a comparison between artificial neural networks and vector autoregressive models

    , Article Computational Economics ; 2017 , Pages 1-19 ; 09277099 (ISSN) Ramyar, S ; Kianfar, F ; Sharif University of Technology
    Abstract
    Given the importance of crude oil prices for businesses, governments and policy makers, this paper investigates predictability of oil prices using artificial neural networks taking into account the exhaustible nature of crude oil and impact of monetary policy along with other major drivers of crude oil prices. A multilayer perceptron neural network is developed and trained with historical data from 1980 to 2014 and using mean square error for testing data, optimal number of hidden layer neurons is determined and the designed MLP neural network is used for estimation of the forecasting model. Meanwhile, an economic model for crude oil prices is developed and estimated using a vector... 

    Forecasting crude oil prices: A comparison between artificial neural networks and vector autoregressive models

    , Article Computational Economics ; Volume 53, Issue 2 , 2019 , Pages 743-761 ; 09277099 (ISSN) Ramyar, S ; Kianfar, F ; Sharif University of Technology
    Springer New York LLC  2019
    Abstract
    Given the importance of crude oil prices for businesses, governments and policy makers, this paper investigates predictability of oil prices using artificial neural networks taking into account the exhaustible nature of crude oil and impact of monetary policy along with other major drivers of crude oil prices. A multilayer perceptron neural network is developed and trained with historical data from 1980 to 2014 and using mean square error for testing data, optimal number of hidden layer neurons is determined and the designed MLP neural network is used for estimation of the forecasting model. Meanwhile, an economic model for crude oil prices is developed and estimated using a vector... 

    Pattern recognition analysis of gas chromatographic and infrared spectroscopic fingerprints of crude oil for source identification

    , Article Microchemical Journal ; Volume 153 , 2020 Hashemi Nasab, F. S ; Parastar, H ; Sharif University of Technology
    Elsevier Inc  2020
    Abstract
    In this study, a chemometric strategy was developed for analysis of gas chromatographic (GC) and infrared spectroscopic (FT-IR) fingerprints of nine crude oil samples from the main oil wells of Iran to classify them and to find their origins. In this regard, a fractionation method based on saturated, aromatic, resin, and asphaltene (SARA) test was used. Then, these fractions were analyzed by GC-FID and GC–MS. Also, nine crude oil samples were analyzed by FT-IR. The obtained GC fingerprints were aligned using correlation optimized warping (COW) and auto-scaled, and then analyzed using principal component analysis (PCA) and hierarchical cluster analysis (HCA). Evaluation of PCA scores plot... 

    A new experimental and theoretical approach for viscosity Iranian heavy crude oils based on tuning friction theory and friction volume theory parameters

    , Article Inorganic Chemistry Communications ; Volume 139 , 2022 ; 13877003 (ISSN) Farajpour, E ; Jafari Behbahani, T ; Ghotbi, C ; Sharif University of Technology
    Elsevier B.V  2022
    Abstract
    In this research work, Friction Theory and Free Volume Theory are applied to live oil characterized based on SARA TEST for viscosity modeling and make a new model in combination with two equation of state (PR and PC-SAFT). Parameters for pseudo-components are obtained by tuning the viscosity at atmospheric pressure and temperatures of 10, 20, and 40 ℃. A new fitting approach is suggested where the number of fitting parameters is 17 and 12 for FT and FVT model, respectively. These parameters are tuned using the Genetic Algorithm and Particle Swarm Optimization and make eight new models. The results show that PC-SAFT provides viscosity predictions for all models with less deviation from... 

    Effects of asphaltene, resin and crude oil type on the interfacial tension of crude oil/brine solution

    , Article Fuel ; Volume 223 , July , 2018 , Pages 261-267 ; 00162361 (ISSN) Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier Ltd  2018
    Abstract
    In recent years, the behavior of crude oil interfacial tension (IFT) as a function of salt concentration have been investigated. The results found in literature are highly controversial, thus the current experimental study aimed to clarify the reasons behind this by developing a methodology based on extracting asphaltene and resin from three different crude oils and performing elemental analysis on them. In addition, the effect of salinity on the IFT of three studied crude oil was compared with the synthetic crude oil consisted of different weight percent (wt%) of asphaltene and resin in toluene. The obtained results revealed that the IFT of crude oil as a function of salinity depended not... 

    Effects of asphaltene content and temperature on viscosity of Iranian heavy crude oil: Experimental and modeling study

    , Article Energy and Fuels ; Volume 27, Issue 12 , 2013 , Pages 7217-7232 ; ISSN: 08870624 Ghanavati, M ; Shojaei, M. J ; Ahmad Ramazani, S. A ; Sharif University of Technology
    2013
    Abstract
    Heavy and extra heavy crude oils usually have a high weight percentage of asphaltene, which could induce many problems during production to refining processes. Also, asphaltene has the main role on the high viscosity of the heavy and extra heavy crude oils. In this paper, the effects of asphaltene characteristics on the crude oil rheological properties have been experimentally and theoretically investigated using different classes of the suspension models. For experimental investigation, the asphaltene was first precipitated from the original heavy crude oil and then 10 well-defined reconstituted heavy oil samples are made by dispersing the asphaltene into the maltene (i.e., deasphalted... 

    Partial equilibrium modelling of world crude oil demand, supply and price

    , Article Energy Systems ; Volume 8, Issue 1 , 2017 , Pages 217-226 ; 18683967 (ISSN) Masoumzadeh, A ; Most, D ; Ookouomi Noutchie, S. C ; Sharif University of Technology
    Springer Verlag  2017
    Abstract
    Oil production strategies define to a large extent the future of the world crude oil market. This paper aims at modelling the long-term world crude oil supply and demand, as well as the global oil price. The main assumption is that non-OPEC and OPEC oil producers act as price-taker and strategic players respectively. The world crude oil demand is modelled as a linear price dependent function. We compare four scenarios to diagnose the OPEC’s supply behaviour: “cartel”, “oligopoly”, “mixed-cartel” and “mixed-oligopoly”. A Mixed Complementarity Problem, MCP, is used to find the Nash equilibrium point of each game scenario. The OPEC countries maximize their individual total discounted profits in... 

    Effect ­­­­­of ultrasonic irradiation treatment on rheological behaviour of extra heavy crude oil: A solution method for transportation improvement

    , Article Canadian Journal of Chemical Engineering ; Volume 95, Issue 1 , 2017 , Pages 83-91 ; 00084034 (ISSN) Rahimi, M. A ; Ramazani S. A, A ; Alijani Alijanvand, H ; Ghazanfari, M. H ; Ghanavati, M ; Sharif University of Technology
    Wiley-Liss Inc  2017
    Abstract
    The highly viscous property of heavy oil often causes problems in its transportation in pipelines. Mixing heavy oil with light oil as well as ultrasound treatment are viable solutions to this problem. In this study, extra heavy crude oil samples were first diluted with 0, 0.05, 0.1, and 0.15 mL/mL (0, 5, 10, and 15 vol%) of a light crude oil; then the mixture was irradiated by ultrasonic waves for 0, 5, 10, 15, and 20 min; finally the viscous shear functions of all mixtures was measured at different values of shear rate at different temperature levels. The results revealed that the minimum viscosity of the diluted extra heavy crude oil samples was obtained at 10 min of ultrasonic... 

    Evaluation of the Impact of Changes in Properties of Crude Oil on Technical Features of Petroleum Supply Chain

    , M.Sc. Thesis Sharif University of Technology Mirzaie Shanjani, Mohammad Mahdi (Author) ; Saboohi, Yadollah (Supervisor)
    Abstract
    Energy system of each country include of extraction, processing, conversion, transportation and distribution levels. Crude oil is one of the energy carrier which has dominant share to meet energy demand in industry and transportation sectors. Therefore, studying of physical properties changes of this energy carrier during production period is obligatory. The goal of this research is to model quality reduction of crude oil during production period of naturally occurring reservoirs. In this research quality of crude oil has been investigated inside of reservoir and after production and the effect of quality changes in before mentioned conditions according to cumulative production of reservoirs... 

    Temperature and composition effect on CO2 miscibility by interfacial tension measurement

    , Article Journal of Chemical and Engineering Data ; Volume 58, Issue 5 , March , 2013 , Pages 1168-1175 ; 00219568 (ISSN) Zolghadr, A ; Escrochi, M ; Ayatollahi, S ; Sharif University of Technology
    2013
    Abstract
    Crude oil reservoirs have different temperatures, compositions, and pressures, therefore oil recovery performance by CO2 injection varies from one case to another. Furthermore, it is predicted that lower interfacial tension between injected CO2 and reservoir fluid results in more oil recovery. In this study, we investigate the effect of temperature on the equilibrium interfacial tension between CO2 and three different oil fluids at different pressures. Also minimum miscible pressure (MMP) is measured by the vanishing interfacial tension (VIT) technique to determine the temperature effect on the CO2 miscible gas injection. The results on different pure and mixtures of hydrocarbon fluids show... 

    The prediction of the density of undersaturated crude oil using multilayer feed-forward back-propagation perceptron

    , Article Petroleum Science and Technology ; Volume 30, Issue 1 , 2011 , Pages 89-99 ; 10916466 (ISSN) Rostami, H ; Shahkarami, A ; Azin, R ; Sharif University of Technology
    2011
    Abstract
    Crude oil density is an important thermodynamic property in simulation processes and design of equipment. Using laboratory methods to measure crude oil density is costly and time consuming; thus, predicting the density of crude oil using modeling is cost-effective. In this article, we develop a neural network-based model to predict the density of undersaturated crude oil. We compare our results with previous works and show that our method outperforms them  

    Effect of asphaltene and resin on interfacial tension of acidic crude oil/ sulfate aqueous solution: Experimental study

    , Article Fluid Phase Equilibria ; Volume 414 , 2016 , Pages 149-155 ; 03783812 (ISSN) Lashkarbolooki, M ; Ayatollahi, S ; Sharif University of Technology
    Elsevier  2016
    Abstract
    Although the capability of using sulfate anion as a wettability modiffier is well established, no systematic investigation on the effect of sulfate ions and natural surfactants in the crude oil including asphaltene and resin on the interfacial tension (IFT) of acidic crude oil (ACO)/sulfate were performed. In this regards, the fluid/fluid interactions are tested through the IFT measurements for ACO, asphaltene and resin extracted from ACO in the presence of sulfate salts including Na2SO4, MgSO4 and CaSO4 while the concentration of each salt ranges between 0 and 45000 ppm. The obtained results demonstrate that the capability of asphaltene molecules is higher for IFT reduction compared with... 

    The role of CO2 and ion type in the dynamic interfacial tension of acidic crude oil/carbonated brine

    , Article Petroleum Science ; Volume 16, Issue 4 , 2019 , Pages 850-858 ; 16725107 (ISSN) Lashkarbolooki, M ; Zeinolabedini Hezave, A ; Ayatollahi, S ; Sharif University of Technology
    China University of Petroleum Beijing  2019
    Abstract
    The effects of CO2 and salt type on the interfacial tension (IFT) between crude oil and carbonated brine (CB) have not been fully understood. This study focuses on measuring the dynamic IFT between acidic crude oil with a total acid number of 1.5 mg KOH/g and fully CO2-saturated aqueous solutions consisting of 15,000 ppm of KCl, NaCl, CaCl2 and MgCl2 at 30 °C and a wide range of pressures (500–4000 psi). The results of IFT measurements showed that solvation of CO2 into all the studied aqueous solutions led to an increase in IFT of acidic crude oil (i.e., comparison of IFT of crude oil/CB and crude oil/brine), while no significant effect was observed for pressure. In contrast, the obtained... 

    New insight on dynamic behavior of swelling and bond number of light and heavy crude oil during carbonated water flooding

    , Article European Physical Journal Plus ; Volume 135, Issue 1 , January , 2020 Lashkarbolooki, M ; Zeinolabedini Hezave, A ; Riazi, M ; Ayatollahi, S ; Sharif University of Technology
    Springer  2020
    Abstract
    Improving oil recovery and decreasing greenhouse gas emissions are two important attractive features of CO2-enriched water injection into oil reservoirs. Regarding these unique features, the main objective of this study was concentrated to evaluate the swelling behavior of crude oil as a fundamental mechanism of carbonated water (CW) flooding. To achieve these goals, the swelling and Bond number of light and heavy crude oils (namely LCO and HCO, respectively) are measured and compared to each other. The results obtained from the measured swelling factors of crude oil/CW show some complicated behaviors. That is, as temperature increases the swelling factor decreases at low pressure... 

    Experimental determination of interfacial tension and miscibility of the CO2-crude oil system; Temperature, pressure, and composition effects

    , Article Journal of Chemical and Engineering Data ; Vol. 59, issue. 1 , December , 2014 , p. 61-69 ; ISSN: 00219568 Hemmati-Sarapardeh, A ; Ayatollahi, S ; Ghazanfari, M. H ; Masihi, M ; Sharif University of Technology
    Abstract
    Interfacial tension (IFT) as one of the main properties for efficient CO2 flooding planning in oil reservoirs depends strongly on pressure, temperature, and composition of the reservoir fluids. Therefore, it is important to measure this property at real reservoir conditions for successful field development plan. In this study, an axisymmetric drop shape analysis (ADSA) has been utilized to measure the equilibrium IFTs between crude oil and CO2 at different temperatures and pressures. Moreover, minimum miscibility pressures (MMP) and first-contact miscibility pressures (P max) of crude oil/CO2 systems at different temperatures are determined by applying the vanishing interfacial tension (VIT)... 

    Investigation of Oil-Asphaltene Slurry Rheological Behavior

    , Article Journal of Dispersion Science and Technology ; Vol. 35, issue. 8 , Aug , 2013 , p. 1155-1162 ; ISSN: 01932691 Tavakkoli, M ; Taghikhani, V ; Pishvaie, M. R ; Masihi, M ; Panuganti, S. R ; Chapman, W. G ; Sharif University of Technology
    Abstract
    The presence of asphaltene means additional difficulties related to transport and processing due to the increased crude oil viscosity caused by the asphaltene. For a better knowledge of the flow properties of asphaltene containing crude oils, it is necessary to understand how asphaltene affects the rheological properties. The aim of this article is to provide information on such rheological properties of oil-asphaltene slurry systems. The results of rheological experiments show that the non-Newtonian flow curves can be approximated by the Bingham plastic model to determine the apparent viscosity and the yield stress as a function of asphaltene concentration and temperature. An explanation is... 

    Effects of paraffinic group on interfacial tension behavior of CO 2-asphaltenic crude oil systems

    , Article Journal of Chemical and Engineering Data ; Vol. 59, issue. 8 , 2014 , Pages 2563-2569 ; ISSN: 00219568 Mahdavi, E ; Zebarjad, F. S ; Taghikhani, V ; Ayatollahi, S ; Sharif University of Technology
    Abstract
    The interfacial tension (IFT) of a crude oil/CO2 system is recognized as the main property affecting the efficiency of CO2 flooding during an enhanced oil recovery (EOR) process. The addition of a paraffin group hydrocarbon to asphaltenic crude oils as an asphaltene precipitant component is aimed to mimic the asphaltene precipitation process during crude oil production and transportation. Asphaltene precipitation would critically affect the interfacial behavior of crude oil/CO2 systems. In the first part of this study, the equilibrium densities of oil samples which contain n-heptane at different ratios were measured over varying pressures at 323 K. Then, the equilibrium IFT between CO2 and... 

    Precipitated asphaltene amount at high-pressure and high-temperature conditions

    , Article Energy and Fuels ; Vol. 28, Issue. 3 , 2014 , pp. 1596-1610 ; ISSN: 08870624 Tavakkoli, M ; Panuganti, S. R ; Taghikhani, V ; Pishvaie, M. R ; Chapman, W. G ; Sharif University of Technology
    Abstract
    In the upstream asphaltene flow assurance community, both academics and industries are actively involved to predict the asphaltene deposit profile in wellbores and pipelines. Essential information for such a study is the amount of asphaltenes that can precipitate and, hence, deposit. In this work, the perturbed chain form of the statistical associating fluid theory (PC-SAFT) is applied to predict the asphaltene precipitation onset condition as well as the amount of precipitate under pressure depletion and high-pressure and high-temperature gas injection conditions. Previous PC-SAFT asphaltene studies in crude oil required the compositional data for both flashed gas and flashed liquid. This... 

    Reservoir oil viscosity determination using a rigorous approach

    , Article Fuel ; Vol. 116, issue , 2014 , p. 39-48 Hemmati-Sarapardeh, A ; Shokrollahi, A ; Tatar, A ; Gharagheizi, F ; Mohammadi, A. H ; Naseri, A ; Sharif University of Technology
    Abstract
    Viscosity of crude oil is a fundamental factor in simulating reservoirs, forecasting production as well as planning thermal enhanced oil recovery methods which make its accurate determination necessary. Experimental determination of reservoir oil viscosity is costly and time consuming. Hence, searching for quick and accurate determination of reservoir oil viscosity is inevitable. The objective of this study is to present a reliable, and predictive model namely, Least-Squares Support Vector Machine (LSSVM) to predict reservoir oil viscosity. To this end, three LSSVM models have been developed for prediction of reservoir oil viscosity in the three regions including, under-saturated, saturated... 

    Prediction of wax disappearance temperature using artificial neural networks

    , Article Journal of Petroleum Science and Engineering ; Volume 108 , 2013 , Pages 74-81 ; 09204105 (ISSN) Moradi, G ; Mohadesi, M ; Moradi, M. R ; Sharif University of Technology
    2013
    Abstract
    In this study, the artificial neural network (ANN) was used for the prediction of WDT. The inputs to network are molar mass and pressure, and the output is WDT at each input. A two-layer network with different hidden neurons and different learning algorithms such as LM, SCG, GDA and BR were examined. The network with 16 hidden neurons and Levenberg-Marquardt (LM) train function showed the best results in comparison with the other networks. Also, the predicted results of this network were compared with the thermodynamic models and better accordance with experimental data for ANN was concluded