DOCSLIB.ORG

Polydispersity of Heavy Organics in Crude Oils and Their Role in Oil Well Fouling

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Polydispersity of Heavy Organics in Crude Oils and Their Role in Oil Well Fouling Journal of Petroleum Science and Engineering Volume 58, Pages 375 – 390, 2007 Polydispersity of Heavy Organics in Crude Oils and their Role in Oil Well Fouling ⁎ 1 2 1, ,** G.Ali Mansoori , Dynora Vazquez , Mojtaba Shariaty-Niassar (1). Departments of Bio and Chemical Engineering (M/C 063), University of Illinois at Chicago, Chicago, IL 60607-7052, USA (2). Department of Chemical Engineering, Daneshkadeh Fanni, University of Tehran, Tehran, Iran Abstract In this report, the polydisperse data of heavy organic fractions of crude oil and solid deposit were produced to investigate the causes of deposition in oil wells. The oilfields of the study have experienced, for several years, shutdowns and decrease in the production ratios due to heavy organics deposition. Several measures such as mechanical cleaning and periodic aromatic washes have been adopted to maintain the production level; nevertheless the costs associated with these procedures are very high. The SARA method was employed to separate the samples into four distinct fractions, namely Saturates, Aromatics, Resins and Asphaltenes. The total asphaltene content of the crude oil samples was determined using n-pentane, n-heptane, and n-nonuse as the precipitating solvents. Polydispersity and molecular weight of each fraction have been further characterized by Gel Permeation Chromatography (GPC). The presence of diamondoids in the solid deposits was also investigated by GC-MS. This technique has been carried out on various crude oil samples collected from an oil field. The results provided useful information on the interaction between the various heavy organic species responsible for the deposition phenomena. Solid samples from different wells resulted in similar composition concluding that these crude oils undergo similar deposition mechanisms. These studies showed that the crude oils produced from different wells in this oilfield are very similar in nature. The asphaltenes contained in some of the crude oil samples displayed a rather strong tendency to self-associate; they also render the highest amounts of precipitation. While diamondoids and alkyl-substituted diamondoids were confirmed to be present in the crude oils produced no evidence was found of their occurrence in the deposits. The polydispersity analysis procedure presented here provides a good understanding of the overall behavior of the species that precipitate and also of the interactions among these species. It is concluded that while most of the heavy organics contained in these crude oils may produce precipitates, asphaltene is the major cause of flocculation of the precipitates, which may result in deposition and plugging of oil-producing wells. © 2007 Elsevier B.V. All rights reserved. (*) Corresponding author. E-mail: [email protected] 1. Introduction (**). Permanent address: National Polytechnic Institute (IPN), The recovery of useful products from petroleum has Interdisciplinary Professional Unit of Biotechnology (UPIBI), been for several years an increasingly important task Department of BioEngeneering, Av. Acueducto s/n Ticoman that is based on the understanding of the physicochem- 07340 Mexico, D.F. Mexico. Email: [email protected] ical properties of the crude oil mixture. During the past several years, extensive research works were devoted to Mojtaba Shariaty-Niassar Email: [email protected] the formulation of models to predict the complex phase Polydispersity of Heavy Organics in Crude Oils and their Role in Oil Well Fouling G.A. Mansoori et al., J. Petrol. Sci. & Eng'g 58, 375-390, 2007 376 transitions in petroleum fluids during production and named flocs (or supramolecules). Flocs could precipitate processing (Park and Mansoori, 1988a,b; Pacheco- out of the mixture as solid deposits which in many cases Sanchez and Mansoori, 1989; Kawawaka et al., 1991; would plug wells, pipelines and processing equipment. Park et al., 1993; Branco et al., 2001; Hu et al., 2004). Some of the mechanisms by which these phenomena Moreover, the potential appearance of solid deposits in occur are known (Kawanaka et al., 1989; Mansoori, wells, pipelines and equipment with unfavorable eco- 1997), but the exact mechanism is still not well un- nomic and operational consequences, requires predictive derstood. It is clear that stability of each species depends models which could successfully predict the conditions upon the nature and amount of the other species in the under which solids form. Thus, based on standardized crude oil. Therefore the characterization of all the analysis of gas and oil, engineers dealing with these constituents of the crude oil may give us an insight into fluids can consider possible actions to prevent or correct their stabilities and interactions. solid formation such as altering operating conditions or The characterization of petroleum into fractions with introducing chemical inhibition. homogeneous physicochemical properties is primarily The need to understand the appearance of solid made by distillation or simulated distillation through gas deposits in crude oils leads us to develop methods of chromatography on the basis of volatility (Green et al., characterization in order to analyze the different types of 1964). Typically, the PVT laboratory will generate the species, which may form solid particles and their behavior data for a fluid by depressurization of a bottom-hole or in crude oils. reconstituted oil sample to obtain separate liquid and gas fractions. The gas–oil ratio (GOR) is recorded and the 1.1. Characterization separated fractions are analyzed by gas chromatography (GC) to obtain their compositions. For the separated gas, For petroleum fluids composition and properties vary the components are quite real discrete components of continuously from the simplest structures to macromo- known molecular weights. The GC analysis of the liquid lecules. Characterization is a key first step to understand also identifies some discrete components, but most of the stability of the crude oil and implement measures to the heavy-end components cannot be identified by GC prevent its break up to vapor, liquid and solid (known as analysis alone. Conventionally, the GC analysis is ex- deposit). Once the characterization is accomplished and pressed as a series of single carbon number cuts termi- suitable data is generated, by using appropriate molec- nating with a Cn+ fraction that specifies the remainder ular, macromolecular and kinetic theories a set of (Chorn and Mansoori, 1989). equations that represent the physicochemical properties and behavior of the petroleum fluid to a satisfactory level 1.2. Heavy fraction analysis of accuracy may be developed. The common problem onemustfaceconsiststhenofidentificationofthe Within the crude oil, the heavy fraction is the most discrete components of the crude, the definition of troublesome due to the presence of a large variety of families or fractions of similar components and under- heavy organic compounds. These compounds are gen- standing the nature and role of interactions in between erally complex and it is difficult to exactly identify them various species. based on their chemical structures. The characterization The complete and detailed characterization of a pe- of the heavy fraction is then based on the identification troleum fluid is quite difficult, time consuming and of a number of families with certain properties which expensive. To simplify the procedure, petroleum is con- can be easily distinguishable from each other. sidered to be composed of a number of light discrete While simulated distillation by gas chromatography components and a heavy end. The heavy end is assumed is a routine means for characterization of the light end, it to consist of four major fractions of similar species. At is not applicable for heavy-end characterization due to the conditions of the original oil in the reservoir the light inability of GC for characterization of large molecules. and heavy ends are mutually soluble forming one phase Therefore the methods employed rely on solubility and so long as certain conditions are maintained in the other chromatographic techniques (Leontaritis and reservoir. Variations in temperature, pressure or com- Mansoori, 1989). The SARA procedure (Jewell et al., position may alter this balance and some of the species 1974) modified for characterization of the heavy end may segregate and form another liquid or solid phase. as already described by Vazquez and Mansoori (2000) Once separated, the complex species may aggregate was used to separate a sample into four classes of com- due to their large size differences, hydrogen bonding pounds, namely saturates, aromatic, resins and asphal- or polar groups interactions and form larger particles tenes. The saturate fraction consists of a viscous whitish Polydispersity of Heavy Organics in Crude Oils and their Role in Oil Well Fouling G.A. Mansoori et al., J. Petrol. Sci. & Eng'g 58, 375-390, 2007 377 translucent liquid mainly composed of paraffins and Table 1 diamondoids. From the four fractions separated from the Composition of crude oil E heavy-end only the saturates fraction is easily distin- Component Mol% Density (g/cm3) Molecular weight guishable and separated from the rest of the oil due to Nitrogen 0.386 the absence of π-bonds in between saturate hydrocarbon Carbon dioxide 1.587 molecules. The aromatic fraction is a viscous reddish Hydrogen sulfide 0.602 liquid composed of aromatic hydrocarbons with various Methane 40.448 Ethane 12.710 degrees of condensation, alkyl-substitution and
Load more

Recommended publications
  • Molecular Interactions Between Asphaltene and Surfactants in a Hydrocarbon Solvent: Application to Asphaltene Dispersion
    S S symmetry Article Molecular Interactions between Asphaltene and Surfactants in a Hydrocarbon Solvent: Application to Asphaltene Dispersion Mohammadali Ahmadi * and Zhangxin Chen Department of Chemical and Petroleum Engineering, Schulich School of Engineering, University of Calgary, Calgary, AB T2N1T4, Canada; [email protected] * Correspondence: [email protected] Received: 21 September 2020; Accepted: 21 October 2020; Published: 26 October 2020 Abstract: Heavy oil and bitumen supply the vast majority of energy resources in Canada. Different methods can be implemented to produce oil from such unconventional resources. Surfactants are employed as an additive to water/steam to improve an injected fluid’s effectiveness and enhance oil recovery. One of the main fractions in bitumen is asphaltene, which is a non-symmetrical molecule. Studies of interactions between surfactants, anionic, and non-anionic, and asphaltene have been very limited in the literature. In this paper, we employed molecular dynamics (MD) simulation to theoretically focus on the interactions between surfactant molecules and different types of asphaltene molecules observed in real oil sands. Both non-anionic and anionic surfactants showed promising results in terms of dispersant efficiency; however, their performance depends on the asphaltene architecture. Moreover, a hydrogen/carbon (H/C) ratio of asphaltenes plays an inevitable role in asphaltene aggregation behavior. A higher H/C ratio resulted in decreasing asphaltene aggregation tendency. The results of these studies will give a deep understanding of the interactions between asphaltene and surfactant molecules. Keywords: asphaltene; oil sand; bitumen; surfactant; dispersant; inhibitor 1. Introduction Precipitation of asphaltene has always been a detrimental process in the oil industry, and a massive amount of effort has been made to keep it dissolved in the oil phase [1–3].
    [Show full text]
  • Seal Coats and Asphalt Recycling
    86 TRANSPORTATION RESEARCH RECORD 1507 Effects of Asphaltenes on Asphalt Recycling and Aging MOON-SUN LIN, RICHARD R. DAVISON, CHARLES J. GLOVER, AND JERRY A. BULLIN Blends made using n-hexane asphaltenes from asphalts, SHRP AAG-1, divided into two quantities, one the increase in log viscosity with AAD-1, and AAK-2 and maltenes from SHRP AAG-1 and AAD-1 asphaltene content and the other the increase in asphaltene content were laboratory-aged to study the effects of asphaltenes on rheological with carbonyl peak growth. properties. For comparison, maltenes from SHRP AAG-1 and AAD-1 as well as their parent asphalts were aged at the same aging conditions as those of blends. The laboratory oxidation conditions were pure oxy­ = ( dlog 11t) = ( dlog 11t )( d%A) (1) gen pressure at 20.7 bar absolute, temperatures of 71.1, 82.2, and HS dCA d%A dCA 93.3°C with aging times from 1to24 days depending on aging temper­ ature. The changes due to oxidative aging were monitored by asphal­ where tene precipitation inn-hexane, Fourier transform infrared spectroscopy, and dynamic mechanical analysis at 60°C. Oxidative aging of asphalts and maltenes results in the formation of carbonyl compounds, the pro­ 11t = zero frequency limit viscosity, duction of asphaltenes, and an increase in viscosity. The change in %A = weight fraction asphaltene, and asphaltene content with respect to the change in carbonyl content is CA = carbonyl peak area. quantified by defining the asphaltene formation susceptibility (AFS). The type of asphaltenes, regardless of their sources, have no effect on The second term in Equation 1, the increase in asphaltene with car­ AFS.
    [Show full text]
  • Asphal Tene Deposition and Its Control
    ASPHAL TENE DEPOSITION AND ITS CONTROL (The Role of Asphaltene in Petroleum Flow Arterial Blockage) G.Ali Mansoori Thermodynamics Research Laboratory University of Illinois at Chicago (M/C 063) Chicago, Illinois 60607-7052 USA E-Mail addresses: [email protected]; [email protected] INTERNET: http://mansoori.people.uic.edu Abstract. Remediation of the heavy organic deposits in the course of petroleum production has been a costly process and it has hampered the production activities in many parts of the world. In this report the authors study the in situ remediation of heavy organics including asphaltene, resin, paraffin I wax, etc. in oil production and transportation practices and its relation with the laboratory and theoretical simulation experiments. it is demonstrated that while asphaltene is the major compound responsible for various arterial blockage cases in the petroleum industry its interaction with other heavy organics is a major factor whether depositions will occur or not. Various mechanisms of asphaltene flocculation and micelle formation are reviewed and illustrative pathways are presented for each mechanism. The current in situ remediation and laboratory simulation practices in the oil industry to combat the problem is reviewed and analysis are made of the cause and effect of each factor influencing them. It is demonstrated that with the development of predictive modelling of heavy organic deposition one can make alterations in the production and transportation schemes to reduce and eliminate the deposition problem. With the development of predictive models one can also screen the candidate dispersants and solvents from the points of view of availability at the site, effectiveness and economy.
    [Show full text]
  • Predicting the Temperature of Hydrocarbon Expulsion from Oil
    Predicting the Temperature of Hydrocarbon Expulsion from Oil Asphaltene Kinetics and Oil Source Correlation: A Case Study of South Cambay Basin, India* By Shishir Kant Saxena1, R.K.Saxena1, Rashmi Anand1, K.P.Singh1, Harvir Singh1, and R.R Singh1 Search and Discovery Article #40266 (2007) Posted November 28, 2007 *Adapted from extended abstract prepared for presentation at AAPG Annual Convention, Long Beach, California, April 1-4, 2007 Editor’s note: Please refer to “Petroleum Systems of the Mumbai Offshore Basin, India, by Goswami et al. (Search and Discovery Article #10154 (2007). 1Geochemistry Labs, KDM Institute of petroleum Exploration, Oil and Gas Corporation Ltd 9 Kaulagarh Road, Dehradun-248195, India ([email protected]) Abstract The oil asphaltene has structural similarity with parent kerogen. The kinetic data based on actual data from the reservoir oil is found to be a better method in reducing the risks associated with oil exploration and assessing the petroleum generation characteristics. An attempt has been made to assess the petroleum expulsion temperature/timing for predicting the kitchen in South Cambay Basin using oil asphaltene kinetics. The Gandhar field covers an area of about 800 km2 and is located on the rising northwestern flank of the Broach depression in the Jambusar-Broach block. The Olpad Formation was deposited during the Paleocene. The Eocene Cambay Shale, unconformably overlying the Olpad Formation, has excellent source rock characteristics. The Hazad Member of south Cambay Basin is a major hydrocarbon reservoir, and it consists of 12-individual sand units from GS-XII-GS-I. The oil asphaltene kinetic/expulsion temperature studies have been carried out on Rock Eval-6 instrument having Optikin and GENEX-1D software.
    [Show full text]
  • Mechanistic Approach to Thermal Production of New Materials from Asphaltenes of Castilla Crude Oil
    processes Article Mechanistic Approach to Thermal Production of New Materials from Asphaltenes of Castilla Crude Oil Natalia Afanasjeva 1, Andrea González-Córdoba 2,* and Manuel Palencia 1 1 Department of Chemistry, Faculty of Natural and Exact Science, Universidad del Valle, Cali 760020, Colombia; [email protected] (N.A.); [email protected] (M.P.) 2 Department of Chemical and Environmental Engineering, Faculty of Engineering, Universidad Nacional de Colombia, Bogotá 111321, Colombia * Correspondence: [email protected]; Tel.: +57-1-316-5000 (ext. 14322) Received: 16 August 2020; Accepted: 23 October 2020; Published: 12 December 2020 Abstract: Asphaltenes are compounds present in crude oils that influence their rheology, raising problems related to the extraction, transport, and refining. This work centered on the chemical and structural changes of the asphaltenes from the heavy Colombian Castilla crude oil during pyrolysis between 330 and 450 ◦C. Also, the development of new strategies to apply these macromolecules, and the possible use of the cracking products as a source of new materials were analyzed. The obtained products (coke, liquid, and gas) were collected and evaluated through the techniques of proton and carbon-13 nuclear magnetic resonance (1H and 13C NMR), elemental composition, Fourier-transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD), saturates, aromatics, resins, and asphaltenes (SARA) analysis, and gas chromatography–mass spectrometry (GC-MS). A comparison of the applied methods showed that the asphaltene molecules increased the average size of their aromatic sheets, lost their aliphatic chains, condensed their aromatic groups, and increased their degree of unsaturation during pyrolysis. In the liquid products were identified alkylbenzenes, n-alkanes C9–C30, and n-alkenes.
    [Show full text]
  • Asphaltene Chemical Structural
    CHARACTERIZATION OF ASPHALTENES STRUCTURE: ASPHALTENE CHEMICAL STRUCTURAL CHANGES DUE TO CARBON DIOXIDE INJECTION A Thesis by NIKOO GOLSHAHI Submitted to the Office of Graduate and Professional Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Chair of Committee, Hisham A. Nasr-El-Din Committee Members, Jerome J. Schubert Mahmoud El-Halwagi Head of Department, Jeff Spath August 2020 Major Subject: Petroleum Engineering Copyright 2020 Nikoo Golshahi ABSTRACT Asphaltenes precipitation during carbon dioxide injection to enhance recovery has been considered as one of the major challenges in the tertiary production phase. How CO2 would change the asphaltenes structure is still unknown. The present study investigates the effects of CO2 on the isolated asphaltenes utilizing various analytical techniques. Chemical structure of precipitated asphaltenes in the presence and absence of CO2 were characterized and compared. These results were coupled with the results of the stability assessment to determine the effects of structural alteration on asphaltenes stability in the oil matrix. Four different crude oils were used to implement this experiment. In the first step, asphaltenes were precipitated by n-heptane. The asphaltenes were then dissolved in toluene and CO2 was injected (at 870 psi) to these solutions and they were mixed at 752°F. This process was repeated for three days, and one week to identify the effect of time on the possible reaction between CO2 and asphaltenes at elevated temperature and pressure. Next, CO2 was injected into the crude oils to determine whether it would react with other components of the oils other than asphaltenes.
    [Show full text]
  • An Investigation Into the Precipitation of Asphaltene from Maltenes Using Binary Mixtures of N-Paraffin
    International Journal of Petroleum and Petrochemical Engineering (IJPPE) Volume 3, Issue 1, 2017, PP 40-45 ISSN 2454-7980 (Online) DOI: http://dx.doi.org/10.20431/2454-7980.0301006 www.arcjournals.org An Investigation into the Precipitation of Asphaltene from Maltenes Using Binary Mixtures of N-Paraffin Utin Mfon Clement, Ofodile S .E, Osuji L. C Department of Pure and Industrial Chemistry, University of Port Harcourt, Choba Port Harcourt, Rivers State, Nigeria Abstract: This work investigates the precipitation of asphaltene from maltenes using single and binary mixtures of n-alkanes. The maltenes was obtained by the precipitation from crude oil using n-alkanes (nC5- nC7). These were deasphalted with a lower carbon number solvent (nC5). The result shows the co-precipitation of the asphaltene are saturates, aromatics and resins. The result obtained generally shows that the asphaltene precipitation from maltenes increased as the n-alkane carbon number of the original precipitating solvent increased. Keywords: Crude oil, n-alkane( n-paraffin), asphaltene, maltene, precipitation, carbon number range. 1. INTRODUCTION During production, transportation and processing, petroleum fluids may go through a number of phase changes which include evaporation (separation of gases from liquid streams), retrograde condensation (separation of liquid from gas stream) and solid formation and deposition (separation of crystalline solids, colloids and aggregates from liquid or vapour streams) which may lead to precipitation and/or deposition of diamonoids, wax and asphaltene (12). Asphaltenes are defined as the fraction separated from crude oil or petroleum products upon addition of hydro-carbon solvents such as n-heptane (14). The formation and deposition of asphaltene-rich, solidlike material during oil recovery operations have been well documented in the literature (7,9, 17).
    [Show full text]
  • Chemical Composition of Asphalt As Related to Asphalt Durability: State of the Art
    Transportation Research Record 999 13 Chemical Composition of Asphalt as Related to Asphalt Durability: State of the Art J. CLAINE PETERSEN ABSTRACT For the purposes of this review, a durable as­ phalt is defined as one that (a) possesses the phys­ ical properties necessary to produce the desired The literature on asphalt chemical composi­ initial product performance properties and (b) is tion and asphalt durability has been re­ resistant to change in physical properties during viewed and interpreted relative to the cur­ long-term in-service environmental aging. Although rent state of the art. Two major chemical design and construction variables are major factors factors affecting asphalt durability are the in pavement durability, more durable asphalts will compatibility of the interacting components produce more durable pavements. of asphalt and the resistance of the asphalt The importance of chemical composition to asphalt to change from oxidative aging. Histori­ durability, although not well understood, cannot be cally, studies of the chemical components of disputed. Durability is determined by the physical asphalt have been facilitated by separation properties of the asphalt, which in turn are deter­ of asphalt into component fractions, some­ mined directly by chemical composition. An under­ times called generic fractions~ however, standing of the chemical factors affecting physical these fractions are still complex mixtures properties is thus fundamental to an understanding the composition of which can vary signifi­ of the factors that control asphalt durability. cantly among asphalts of different sources. The purpose of this paper is to examine the The reaction of asphalt with atmospheric literature dealing with the chemical composition of oxygen is a major factor leading to the asphalt and changes in composition during environ­ hardening and embrittlement of asphalt.
    [Show full text]
  • Critical Review of Asphaltene Properties and Factors Impacting Its Stability in Crude Oil
    Missouri University of Science and Technology Scholars' Mine Geosciences and Geological and Petroleum Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works Engineering 01 Mar 2020 Critical Review of Asphaltene Properties and Factors Impacting its Stability in Crude Oil Sherif Fakher Mohamed Ahdaya Mukhtar Elturki Abdulmohsin Imqam Missouri University of Science and Technology, [email protected] Follow this and additional works at: https://scholarsmine.mst.edu/geosci_geo_peteng_facwork Part of the Petroleum Engineering Commons Recommended Citation S. Fakher et al., "Critical Review of Asphaltene Properties and Factors Impacting its Stability in Crude Oil," Journal of Petroleum Exploration and Production Technology, vol. 10, pp. 1183-1200, Springer, Mar 2020. The definitive version is available at https://doi.org/10.1007/s13202-019-00811-5 This work is licensed under a Creative Commons Attribution 4.0 License. This Article - Journal is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact [email protected]. Journal of Petroleum Exploration and Production Technology (2020) 10:1183–1200 https://doi.org/10.1007/s13202-019-00811-5 REVIEW PAPER - PRODUCTION ENGINEERING Critical review of asphaltene properties and factors impacting its stability in crude oil Sherif Fakher1 · Mohamed Ahdaya1 · Mukhtar Elturki1 · Abdulmohsin Imqam1 Received: 13 September 2019 / Accepted: 24 November 2019 / Published online: 5 December 2019 © The Author(s) 2019 Abstract Asphaltene is a component of crude oil that has been reported to cause severe problems during production and transporta- tion of the oil from the reservoir.
    [Show full text]
  • 1H- and 13C-Nmr Structural Characterization of Asphaltenes from Vacuum Residua Modified by Thermal Cracking
    CT&F1 H-- Ciencia, AND 13TecnologíaC-NMR STRUCTURAL y Futuro - Vol. CHARACTERIZATION5 Num. 4 Jun. 2014 Pag.OF ASPHALTENES49- 60 FROM VACUUM RESIDUA MODIFIED BY THERMAL CRACKING ISSN (Print) 0122-5383 ISSN (Online) 2382-4581 Journal of oil, gas and alternative energy sources 1H- AND 13C-NMR STRUCTURAL CHARACTERIZATION OF ASPHALTENES FROM VACUUM RESIDUA MODIFIED BY THERMAL CRACKING CARACTERIZACIÓN ESTRUCTURAL POR RMN-1H y 13C DE ASFALTENOS DE RESIDUOS DE VACÍO MODIFICADOS POR RUPTURA TÉRMICA Juan-Carlos Poveda*1, Daniel-Ricardo Molina1 and Edgar-Francisco Pantoja-Agreda2 1Universidad Industrial de Santander, Bucaramanga, Santander, Colombia 2Corporación para la Investigación de la Corrosión, Piedecuesta, Santander, Colombia e-mail: [email protected] (Received: Jan. 08, 2014; Accepted: Jun. 17, 2014) ABSTRACT 1 - and 13C-NMR data were used to characterize asphaltenes and to follow their chemical changes when they were exposed to thermal cracking under different thermal conditions (673, 693 and H713 K), and treatment times (10, 20 and 30 minutes). Samples of asphaltenes were obtained from a Vacuum Residue (VR) of a mixture of Colombian crude oils. Samples were previously characterized by elemental analysis. Since the characterization of the aromatic substructure is important for this work, special attention was given to those regions in the 1H- and 13C-NMR spectra that showed the main changes: p.e. methyl hydrogens -in gamma position or more- to aromatic units ; methyl hydrogens -in beta positions- to aromatics units ; methylene hydrogens -in beta position- to aromatics ; hydrogens -in naphthenic units beta- to aromatics ; hydrogens -in paraffinic and alpha position naphthenic structures-in - to aromatics ; hydrogens in monoaromatic units ; hydrogens in polyaromatics ; carbons in methyl groups ; carbons in methyl groups -in alpha position- to aromatics ; protonated aromatic carbons ; pericondensed aromatic carbons CAAA; aromatic carbons linked to methyl groups; catacoWndensed aromatic carbons CAA and aromatic carbons linked to paraffinic or naphthenic structures .
    [Show full text]
  • Characterisation of Asphaltenes Extracted from an Indonesian Oil Sand Using NMR, DEPT and MALDI-TOF
    Available online at www.sciencedirect.com ScienceDirect Energy Procedia 75 ( 2015 ) 847 – 852 The 7th International Conference on Applied Energy – ICAE2015 Characterisation of Asphaltenes Extracted from an Indonesian Oil Sand Using NMR, DEPT and MALDI-TOF Ce Zheng, Mingming Zhu* and Dongke Zhang Centre for Energy (M473), The University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia Abstract This paper reports the findings of a preliminary study into the molecular structure and properties of asphaltenes extracted from an Indonesian oil sand, Buton Oil Sand. The molecular structural parameters of the asphaltenes were determined using liquid 13C NMR spectrum in combination with DEPT. The molecular weight distribution of the asphaltenes was measured using MALDI-TOF mass spectrometer. The results indicated that the representative molecular structure of the asphaltenes from Buton Oil Sand predominately contained only one PAH core of 6 rings with an average molecular weight around 800 Da. The results also showed that the use of 13C NMR spectrum/DEPT provided a powerful tool and useful method for characterising and predicting the molecular structures of asphaltenes. ©© 2015 2015 The The Authors. Authors. Published Published by Elsevier by Elsevier Ltd. This Ltd. is an open access article under the CC BY-NC-ND license (Selectionhttp://creativecommons.org/licenses/by-nc-nd/4.0/ and/or peer-review under responsibility). of ICAE Peer-review under responsibility of Applied Energy Innovation Institute Keywords: Asphaltenes; DEPT; MALDI-TOF; Moleculer structure; NMR; Oil sand 1. Introduction Oil sand comprises a significant proportion of the world’s oil reserves [1, 2]. The extraction and processing of hydrocarbons from oil sand are very challenging due to the high viscosity of the bitumen and the chemical impurities such as sulphur.
    [Show full text]
  • Influence of Asphaltene Aggregation and Pressure on Crude Oil Emulsion Stability Influence of Asphaltene Aggregation and Pressure on Crude Oil Emulsion Stability
    ttGOAosMSM Inge Harald Auflem Influence of Asphaltene Aggregation and Pressure on Crude Oil Emulsion Stability Influence of Asphaltene Aggregation and Pressure on Crude Oil Emulsion Stability by Inge Harald Auflem Thesis Submitted in Partial Fulfilment of the Requirements for the Degree of DOKTOR INGENI0R Department of Chemical Engineering Norwegian University of Science and Technology Trondheim, June 2002 Preface Preface This thesis, submitted in partial fulfilment of the requirements for the degree of dr.ing. at the Norwegian University of Science and Technology, consists of five articles, one patent and one book chapter. The thesis is based on work performed at Statoil Research Centre, the Institute for Surface Chemistry in Stockholm, and Chalmers University of Technology in Gothenburg in the period from August 1999 to June 2002. My supervisor introduced me to the field of surface and colloid chemistry in 1997, while studying physical chemistry as an undergraduate student at the University of Bergen. Little did I then know that the work would lead me into the petroleum industry, and a struggle with "the good and the bad asphaltenes". As an experimentalist, the work in the laboratory has, more often than not, provided results difficult to interpret. Nevertheless, the work has continued, and in-between the total failures, there has been some near successes, which have resulted in the thesis you are now paging through. During my time as a dr.ing. student I have had the fortune to participate in a project with the acronym FLUCHA II, which stands for Fluid Characterisation at elevated pressures and temperatures. The group has consisted of 3 dr.ing.
    [Show full text]