MATURITY-DEPENDENT GEOCHEMICAL MARKERS OF CRUDE PETROLEUMS FROM EGYPT

ABSTRACT

Maturity-dependent trends of a number of biomarker and nonbiomarker geochemical parameters were examined in crude oils from the Western Desert and the Gulf of Suez, Egypt. Molecular maturity assessments showed that all oils are at an advanced level of thermal maturity, and many ratios, such as CPI, hopane/hopane + moretane, C₃₁ 22S/22S + 22R hopanes and C₂₉ ααα-20S/20S + 20R steranes were almost identical and have reached their thermal equilibrium values. Changes in the Ts/Tm and C₂₉ ββ/(ββ + αα) steranes however, showed a more advanced level of thermal maturity for Umbaraka oil. On the other hand, correlations utilizing the nonbiomarkers API gravity, ΣV, Ni, sulfur content, sat/arom, and Ph/n-C₁₈ ratios did show more distinct differences and are consistent between the oils.     

Light hydrocarbon geochemistry of crude oils from Eastern Niger Delta

Abstract

Geochemical evaluation of oil samples from the eastern part of the Niger Delta divided into western, eastern, and central sections of the study area was carried out for the characterization of their light hydrocarbons content in order to correlate oils from different parts. The hydrocarbons in the oil samples were determined using gas chromatographic (GC) technique. The results obtained showed that CPI, Pr/Ph, Pr/nC₁₇, and Ph/nC₁₈ ratios ranged from 0.99–1.55, 2.19–4.79, 0.92–2.35, and 0.27–0.47, respectively. The Pr/nC₁₇ versus Ph/nC₁₈ plot showed that the oils were derived from terrestrial organic materials that were deposited under oxic to suboxic conditions. They are moderately matured with minimal effect of biodegradation on most of the oil samples although two of the oils showed relatively higher degradation. Both bivariate and multivariate plots of the light hydrocarbon ratios differentiated the western and central oils from the eastern oils. The classification of the oils into families was not based on origin but rather on post generative alterations that include reservoir conditions and possibly migration effects. The light hydrocarbon parameters identified can be used in the correlation tools.     

Geochemical characteristics of hydrocarbons in different states during oil-filling process of the Upper Triassic Chang 8 formation,Ordos basin,China

Abstract

Four oil-bearing sandstone samples of Chang 8 sub-unit were collected from Ordos basin and geochemical characteristics of hydrocarbon in different states during oil-filling process were determined. The occurrence of hydrocarbon in sandstone can be divided into four types by using sequential extraction. The features of alkanes, the diagram of Pr/nC₁₇ versus Ph/nC₁₈ and the cross plot of MPI-1 versus R_c show that four type hydrocarbons derived from same source rock, the organic matter includes aquatic organisms and higher plants, moreover, the thermal maturity of the free hydrocarbon is the highest, followed by the sealed hydrocarbon and the cement hydrocarbon, and the inclusion hydrocarbon is the lowest. The variation of geochemical features of hydrocarbons in different states may result from continuous oil-charging in geological history.     

AN EXPERIMENTAL STUDY OF THE EFFECT OF PARAFFINIC SOLVENTS ON THE ONSET AND BULK PRECIPITATION OF ASPHALTENES

ABSTRACT

Asphaltene onset concentration and bulk deposition were measured for a typical live reservoir oil titrated with n-C₆H₁₄, n-C₅H₁₂, n-C₄H₁₀, C₃H₈, C₂H₆, CH₄ and CO₂ at 100° C (212 ° F) and 29.9 MPa (4340 psia). The concentration of titrant at asphaltene onset was observed to decrease approximately in a linear fashion with decreasing molecular weight of the paraffinic solvent; CH₄ did not induce any asphaltene precipitation. Bulk deposition experiments were performed using a solvent: oil volume ratio of 10:1; the results indicated that the weight percent of asphaltenes precipitated increased exponentially with decreasing molecular weight of the paraffinic solvents. More importantly, the asphaltene molecular weight showed a maximum for n-C₄H₁₀ precipitated asphaltenes. Possible explanations for this unusual result are presented.     

New Generalized One-Parameter Vapor Pressure Formula of Homologous Pure Hydrocarbon Series

Abstract

Generalized formula has been developed to calculate vapor pressure of pure hydrocarbon series (C _n H_2n+2) from C₁₁H₂₄ to C₃₅H₇₂ based on one parameter “carbon number” only. As a result this technique is considered to be useful for prediction of vapor pressure of pure hydrocarbons, since it is possible to use this formula depending on simple parameter “carbon number”.     

Investigate the physical and rheological properties of asphalt binders modified with barium sulfate nanoparticles

Abstract

The aim of this study is to investigate the physical and rheological properties of modified asphalt binders with barium sulfate (BaSO₄) nanoparticles. The penetration grade test and the softening point test on the controlled and modified asphalt binders showed that the presence of nanoparticles improved the physical properties of asphalt binders. Dynamic shear rheometer (DSR) test was performed on the main and modified asphalt binders in unaged and short-term aged modes. The asphalt binders containing 2% of nanoparticles in each of the unaged and short-term aged modes have the maximum value of rutting parameter at all temperatures.     

THE COLLOIDAL ASPECT OF A MACROSTRUCTURE OF PETROLEUM ASPHALT

ABSTRACT

Petroleum asphalt contains asphaltene which is peptized with resin fraction molecules and is dispersed in an intermicellar medium consisting of saturates and aromatics (gas oil fraction). The single sheet of asphalcic molecules, determined by a variety of instrumental methods, has an average size of 0.5 × 1.5 nm. These mesomorphic units as evaluated by x-ray diffraction contain ordered nuclei of L_c with 1.0 - I.S nm and L_c of 2.0?nm. The micellar structure can be evaluated from petroleum, asphalt, or asphattene suspended in any medium by small angle x-ray or neutron scattering to yield a morphological diameter measuring ca. 10?nm. The tendency of these units to be associated has been investigated by a number of investigators, for example, electron microscopic techniques such as freeze-fracture, holycarbon and metal shadowing have indicated a cluster diameter of 100 - 1000?nm. The upper range of these clusters (super-micelles) can again agglomerate into a giant size of agglomerate on the order of 2 - 10 μm, which corresponds to a typical floe weight. At high temperature these supermicelles can form two-dimensional liquid crystalline mesophase spherules with sizes varying from 2 to 5?μm     

CHARACTERIZATION OF THIOLS IN PRESWEETENING AND SWEETENED RFCC GASOLINE DISTILLATE

ABSTRACT

Thiols in RFCC naphthas produced in two refineries in China have been separated and characterized with GC/FPD. The identification results show that there are more than 20 kinds of thiols, including C₃-C₈ normal thiols, isothiols, thiophenol and methylthiophenol presenting in presweetening RFCC naphthas, while in sweetened RFCC naphthas, only have the isothiols and C₇-C₈ normal thiols been detected. The content of C₇-C₈ thiols and isothiols is higher in RFCC naphthas than that in FCC naphthas.     

THE ANALYSIS OF METALLOPORPHYRINS IN PETROLEUM USING TANDEM MASS SPECTROMETRY

ABSTRACT

Vanadyl deoxophy lloerythroetioporphyrins (DPEP) and vanadyl etioporphyrins (ETIO) have been identified in Gato Ridge and Boscan petroleum samples using a combination of isobutane chemical ionization and tandem mass spectrometry. In addition, particular porphyrins such as the C₃₀ vanadyl DPEP and ETIO species were identified in a crude oil containing approximately 500 ppm total porphyrins, with only minimal sample clean-up.     

SUPPLY AND DEMAND OF LIGHT NAPHTHA AS POTENTIAL PETROCHEMICAL FEEDSTOCK IN SAUDI ARABIA

ABSTRACT

Saudi Arabia is a major crude oil producer and exporter. Additionally, with the completion of its master gas gathering and treatment system petrochemical industries became the Kingdom's second major industrial sector. Currently, the Saudi petrochemical industry depends mainly on (C₁) methane and (C₂) ethane components of associated gas (AG) and natural gas (NG) as feedstocks. A variety of basic petrochemicals are now being produced principally by plants of the Saudi Basic Industries Corporation (SABIC).

There is a necessity of enhancing the use of various under-utilized hydrocarbon resources. At present, one of the favored under-utilized resources and potential candidates for upgrading is light naphtha (LN). Because LN has the advantage of producing a more diverse petrochemical product portfolio than C₁ and C₂ components, it is expected that LN will assume an increasing importance as feedstock in the future development of petrochemical industries in Saudi Arabia. However, industrial opportunities for economies of large-scale production of petrochemicals based on LN might not be favored.

Saudi Arabia's chemical and petrochemical industrial sector has not yet been fully developed, and its production lines are not enough diversified to benefit from LN. The development and expansion of Saudi petrochemical industries usually follows the international trend in this sector, and benefits from its technological achievements. Worldwide global shift in the use of feedstock in this industrial sector will be reflected in the Saudi petrochemical industries. As the world trend is to maximize the utilization of under-utilized petroleum resources, one would expect optimization of LN utilization in Saudi Arabia in the near future.     

GEOCHEMICAL SIGNIFICANCE OF FATTY ACIDS IN CRUDE OILS AND RELATED SOURCE ROCKS FROM EGYPT

ABSTRACT

The acid fraction of crude oils and related source rocks of different stratigraphic units from the Gulf of Suez and Western Desert, Egypt were analyzed by GC and GC/MS. Normal alkanoic acids (n-C₉?n-C₃₀) were the dominant series (with the predominance of even-carbon numbers maximizing at n-C₁₆, n-C₁₈ or n-C₂₂while iso- and anteiso- branched acids were minor constituents. All samples showed a preference of short chain acids (n-C₁₀?n-C₁₉ with respect to long chain acids (n-C₂₀+) typical of marine oils and source rocks. The n-alkanoic acids distribution suggests a predominant algal and/or bacterial contribution. The presence of high relative abundance of mono and di-unsaturated carboxylic acids in a number of samples point to recent microbial activity. Distributions of n-alkanoic acids in the range (C₁₂?C₂₂) show striking similarities with the n-alkane distributions, indicating that both series may, at least in part, be diagenetically related by decarboxylation of the acids. Dehydroabietic acid has been identified in only one sample from Balaim Marine source rock. This resin-derived compound has probably been transported as pollen to the marine environment.     

Ultraviolet and PAV aging procedures influence on rheological characteristics of Sasobit/SBS modified binder containing titanium dioxide nanoparticles

Abstract

The objective of this study is to evaluate the rheological properties of styrene-butadiene-styrene and Sasobit modified asphalt binder blended with various contents (0%, 1%, 3% and 5%) of nano-titanium dioxide (TiO₂) after Ultraviolet (UV) aging and PAV aging procedures. Rheological test results showed that nanoparticles generally had no effect on the complex modulus and phase angle of binders. UV aged binders showed better fatigue and cracking resistance than the PAV aged binders. Finally, compared to the control binder, the binder with nanoparticles had a higher fatigue resistance after UV aged, but worse fatigue resistance after PAV aged.     

Studies on Carbon Number Distribution of High Melting Microcrystalline Waxes

Abstract

Carbon number distribution of microcrystalline wax derived from tank sludges of Bombay High crude oil (India) and its various high melting fractions have been studied by High Temperature Gas Chromatography (HTGC). Binodal, Gaussian distribution and a wide range of alkanes, ranging from C₂₁–C₇₅, along with their many isomers with predominant alkanes being C₄₀ and C₆₇, have been observed in the microcrystalline wax. Higher melting wax fractions have Gaussian distribution.     

STRUCTURAL CHARACTERIZATION OF GUDAO ASPHALTENE BY RUTHENIUM ION CATALYZED OXIDATION

ABSTRACT

Structural characterization of Gudao asphaltene was undertaken by using ruthenium ion catalyzed oxidation (RICO ) which is capable of converting aromatic carbons selectivety to carbon dioxide and/or carboxyUc groups while leaving aliphatic and alicyclic structures essentially unaffected. The oxidation products were dominated by a homologous series of straight chain monocarboxyfic acids ( C₂ -C₃₅) indicating that normal alkyl chains are important constituents of the asphaltene. A series of α,ω; -dicarboxylic acids (C₄ - C₂₆) were also detected and determined, confirming the presence of poh/methylenc mokties linking two aromatic units. Relative high yields of benzenepenta- and hexacarboxyhc acids fonned in the RICO of Gudao asphaltene clearly indicate that substantia] aromatic structures of this asphaltene are peri-condensed.     

OCCURRENCE AND DISTRIBUTION OF n-ALKANESAND n-FATTY ACIDS IN SAUDI ARABIAN CRUDE OILS

ABSTRACT

Ten crude oil samples, covering wide range of maturity (API gravity = 18·5–36·1), were assembled from Safaniya, Abqiq, Ain Dar, Wafra. Marjan and Zuluf oil fields in the area of Arabian Gulf. n-Alkanes of were separated from the petroleum distillate ((150°C–450°C) of the crude oils by urea adduction. n-Fatty acids were separated from the fraction of n-alkanes by treatment with aqueous solution of KOH. Distribution of n-alkanes and n-fatty acids has been investigated by means of gas chromatography. The studied crude oils showed symmetrical distribution curves of n-paraffins and fatty acids of low molecular weight were abundant as compared with n-paraffins. The n-paraffins distribution curve of Wafra/Iucene biodegraded immature crude oil showed three maxima at C₁₇, C₁₉, and C₃₁ whereas the maxima of n-fatty acids are located at C₁₄,C₂₂and C₂₄. The results were interpreted in terms of origin, maturation and depositional environments of the crude oils.     

CHARACTERISATION OF CYCLIC AND ACYCLIC ALKANES CHARACTERISATION OF CYCLIC AND ACYCLIC ALKANES IN FORTIES AND KUWAIT PETROLEUM CRUDES

ABSTRACT

Alkane hydrocarbon fractions from Forties (North Sea) and Kuwait petroleum crudes, separated by distillation, solvent extraction and silica-gel column chromatography and sub-fractionated by molecular-sieve adsorption, have been examined by gas chromatography (GC) ¹H and ¹³C ( NMR spectroscopy, GC-mass spectrometry (MS) and field desorption (FD)MS. GC indicates that Forties contains rather more acyclic isoprenoids and cyclic alkanes than Kuwait; FDMS of Kuwait shows molecular-weight ranges for mono-, di-, tri-, tetra- and pentacyclic alkanes. ¹³C NMR spectra provide evidence of higher aromatic carbon, C_A, in Forties than Kuwait and longer T₁ relaxation times.     

Estimating phase behavior of the asphaltene precipitation by GA-ANFIS approach

Abstract

This study implements an adaptive neuro-fuzzy inference system (ANFIS) approach to predict the precipitation amount of the asphaltene using temperature (T), dilution ratio (R_v), and molecular weight of different n-alkanes. Results are then evaluated using graphical and statistical error analysis methods, confirming the model’s great ability for appropriate prediction of the precipitation amount. Mean squared error and determination coefficient (R²) values of 0.036 and 0.995, respectively are obtained for the proposed ANFIS model. Results are then compared to those from previously reported correlations revealing the better performance of the proposed model.     

New Statistical Concepts for Prediction Viscosity,Critical Temperature,and Critical Pressure of Homologous Hydrocarbon Series (C n H2n+2)

Abstract

A new model for prediction viscosity, critical temperature, and critical pressure for homologous hydrocarbon series C _n H_2n+2 as a function of carbon number only. The new model has a general formula: η or T _c or P = A ₁ C ^{A ₂} (2+2C) ^{A ₃} . This new model provides accurate and computationally reliable prediction for the corresponding properties (η, T _c , and P _c ) value.     

C2 OXYGENATES BY CHLOROMETHANE ADDITION TO SYNGAS

Abstract

A novel two-stage process capable of producing acetaldehyde from methane and syngas (CO and H₂) has been studied. Methane, oxygen, and hydrogen chloride react over an oxyhydrochlorination catalyst in a first stage to produce chloromethane and water. In the second stage, chloromethane is added to a syngas mixture and catalytically converted to C₁ to C₄4 hydrocarbons and acetaldehyde.     

METALLOPETROPORPHYRINS AS PROCESS INDICATORS: MASS SPECTRAL IDENTIFICATION OF Ni(ETIO) AND Ni(DPEP) HOMOLOGOUS SERIES IN GREEN RIVER SHALE OIL

ABSTRACT

Mass spectrometry (MS) of the porphyrin fraction of a demetallated shale oil from the LLNL Hot-Recycled-Solids retorting process exhibited homologous series of C₂₅ to C₃₃ (C₂₈ maximum) for etio and C₂₆ to C₃₆ (C₃₀ maximum) for DPEP (isocyclic) porphyrins, respectively. The sum of intensities after baseline correction yielded a ΣDPEP/Σetio ratio of 1/1. The petroporphyrin fraction was prepared by demetallation of the whole shale oil using methane sulfonic acid followed by isolation which involved extraction and purification by alumina chromatography. MS examination of silica purified fractions showed another type of homologous series, tentatively assigned as tetrahydrobenzo-DPEP por-phyrin. MS examination of porphyrin fractions isolated by alumina or alumina/silica chromatography without demetallation indicated Ni(etio) and Ni(DPEP) (isocyclic) porphyrins were observed with the same homologous series as seen in the demetallated fraction.