S.M. El-Sabagh

API gravities, vanadium, nickel, sulfur, and their relation to gross composition: Implications for the origin and maturation of crude oils in Western Desert, Egypt

ABSTRACT In the present study, the geochemical analyses of API gravities, vanadium, nickel, sulfur, and bulk composition were performed on eight samples from productive wells in Gindi, South Deep Abu-gharadig, Abu-gharadig, Dahab-Merier, and Faghure basins locates in the North Western Desert. The results were used to describe the source organic matter input, depositional environment, assess the degree of thermal maturity, and to correlate between crude oils to determine the genetic relationship between hydrocarbon generation and their source rock for the studied oil samples. The results showed that a wide range of crude oil parameters exists in this data, indicating that a variety of oil types is represented. Crude oils range from unaltered to altered by vanadium, nickel, and sulfur concentrations, V/Ni and saturate fraction were used to classify the oils. Oils are classified into two groups. Group I contains oil samples from Gindi, South deep Abu-gharadig and Abu-gharadig, and Dahab-Merier that are generated from organic matter input deposited in marine environment under anoxic to suboxic conditions. Group II from Faghur basin possess high Pr/Ph ratios suggesting high contribution of terreginous organic matter deposited under relatively oxic conditions.

An Organic Geochemical Characterization of Crude Oils from El Hamd and Bakr Oilfields in the Gulf of Suez, Egypt

Abstract Seven crude oil samples were collected from wells of the El Hamd and Bakr oil fields located in the central Gulf of Suez and their chemical composition, API gravity, sulfur content, and asphaltene content were determined. Nickel and vanadium contents were measured using atomic absorption spectroscopy. Saturated paraffinic hydrocarbon fractions were subjected to gas chromatography in order to investigate carbon number distribution. Terpanes and steranes biomarker distributions have been determined using gas chromatography-mass spectroscopy in order to characterize the type of organo-facies, oil classes, depositional environments of the studied crude oils, and to assess the thermal maturity level for oil generation. It has been found that mature oils are generated from marine shales and carbonates are enriched in marine algae with a contribution from terrestrial organic matters.

Mass Spectrometry of Metalloporphyrins in Egyptian Oil Shales from Red Sea Area

Abstract Metalloporphyrins, extracted from asphaltene and maltene fractions of some Egyptian oil shales (Abu-Shegeili, El-Beida, El-Nakheil, and Abu-Tundub in the Red Sea area) by means of adsorption column chromatography and TLC, were subjected to mass spectrometry in order to elucidate the structure of different types of VO, Ni, or Fe porphyrins. Metalloporphyrins were not detected in maltene or asphaltene fractions of Abu-Shegeili oil shale. The mass spectra appeared as a truncated series of mass numbers, which is characteristic of geo-porphyrins in sediments or oil shales. The data indicated that the five types of porphyrins (Etio, DPEP, BEtio, BDPEP, and THBD) with carbon numbers ranging from C20 to C50 were present in considerable detection levels. Based on mass spectrometric data, the major components of metalloporphyrins (VO, Ni, or Fe) were identified and their chemical structures were suggested. The occurrence and distribution of VO, Ni, and Fe porphyrins were interpreted from a geochemical point of view, particularly maturation levels and oil-gas potentials of kerogens.

Bulk Composition Of Some Saudi Arabian Crude Oils In Relation To Maturation, Origin And Depositional Environments

ABSTRACT Ten crude oil samples, covering wide range of maturity (API = 18.5−36.1), were assembled from Safaniya, Abqiq, Ain-Dar, Wafra, Marjan, and Zulf oil fields in the area of Arabian Gulf. Different analytical techniques, including liquid chromatographic separation, gas chromatography, and nuclear magnetic resonance spectroscopy, were used to characterize the oil samples. Some bulk and specific compositional parameters were used for oil-oil correlations in order to evaluate thermal maturation, origin, biodegradation and depositional environments of the crude oils. Considering the maturity relationships, it was suggested that the bulk composition of Wafra/Iucene crude oil was altered due to biodegradation and vertical migration. Correlation between API gravity and PAP of aromatic fraction indicated two maturity levels of onshore and offshore oil fields. The distribution of n-alkanes reflected the marine origin of the crude oils. Isoprenoids/n-alkanes and pristane/phytane ratios were determined by capil...

MATURATION AND DEPOSITIONAL ENVIRONMENTS OF CRUDE OILS FROM GULF OF SUEZ

ABSTRACT Crude oil samples from the major producing fields in the Gulf of Suez were geochemically assessed to evaluate maturity, origin and depositional environmental trends. Multiple analytical parameters used to charactrizethe petroleum samples included asphaltene content, sulfur content, liquid chromatographic separation, and gas chromatography of the saturated hydrocarbons fraction. From the results obtained, it was suggested that the crude oils are mature. Also, no strong evidence of biodegradation has been observed. Distribution of n-alkanes indicated that the crude oils are derived mainly from marine sedmentary source rocks. Pristane/phytane ratio of the crude oils seemed to be mostly below unity, indicating reducing depositional environments.

FTIR Spectroscopic Studies of Kerogen and Its Pyrolysates from Selected Egyptian Oil Shales

Abstract Pyrolysis of kerogen, isolated from the main producing mines of oil shales (Abu-Shegeili, El-Beida, El-Nakheil, and Abu-Tundub) in the Red Sea area, were studied to investigate their potential as fuel substituents. Kerogen was subjected to dry pyrolysis at different temperatures ranging between 300°C and 550°C. The oil yield shows a progressive increase to reach a maximum at 450°C. El-Nakheil oil shale gave the highest oil yield, while Abu-Shigeili exhibited the lowest amount of oil. The isolated kerogen, pyrolysate, and residual materials were subjected to FTIR spectroscopy to give valuable information about chain length, degree of branching, and degree of substitutions of aromatic structure of kerogen and its pyrolysates.

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.

Characterization and correlation of crude oils from some wells in the North Western Desert, Egypt

ABSTRACT Characterization and correlation of crude oils from some wells in the North Western Desert, based on six crude oil samples, were studied by different analytical techniques, including API gravity, sulfur content, nickel and vanadium, bulk compositions and saturated fraction obtained from gas chromatography have been studied. The results show that the crude oils are normal to medium aromatic oils, with high API gravity and high sulfur content. V, Ni, V/Ni and V/(V + Ni) reflecting oils might be sourced from non-clastic source rocks, possibly carbonates, deposited under anoxic-suboxic conditions. Bulk compositions revealing that the crude oils were derived from marine organic sources. While, the paraffins and naphthenes percent indicates that the oils belong to paraffinic to naphthenic oil types, deposited in slightly anoxic to suboxic conditions and contained marine organic matter. Thermal maturity data showed that the oil samples were generated from mature source rocks. This indicates the studied oil samples are well correlated with each other, where they are similar in their oil type maturation and source depositional environments.

Crude oils geochemistry depended specific properties, metalloporphyrins, bulk compositions, and n-alkanes of some Egyptian oils in the Gulf of Suez, Egypt

ABSTRACT The geochemical analyses of Specific gravity (API), sulfur content, nickel and vanadium, porphyrins, bulk compositions, and saturated fraction obtained from gas chromatography have been studied with the aim of throwing more light on the geochemical aspects of the crude oil formation, migration, and maturation. Seven samples were collected from Sudr, October, GS-283, Belayim land, Belayim marine, Kareem, and July oilfields in the Gulf of Suez. These samples are representative for the producing horizon zones of Rudeis and Nuhkul formations of Middle-Lower Miocene age ranging in depths from 1344 to 3558 m. The studied crude oils are classified into heavy and/or intermediate oils. The crude oils have high concentrations of nickel and vanadium contents. Vanadyl porphyrins indicate mature to moderately mature oils. A gross composition reveals marine organic sources. The n-alkanes and isoprenoids in crude oils are derived from marine organic matter, deposited under anoxic/hypersaline to oxic or carbonate environments associated with evaporate and carbonate depositional environment.