Thesis (M.Sc.) -- University of Calgary, 1998. / Three folded leaves and 3 1/2 in. computer disk in back pocket. 3 folded leaves and 3 1/2 in. computer disk in back pocket. Includes bibliographical references. Also available on microfiche. Available in PDF format via the World Wide Web.

This thesis describes a detailed geochemical evaluation of the Oued Mya-Hassi Messaoud ridge petroleum system, located in the central Sahara-Algeria. The study area consists of several fields: (1) the Devonian and the Lower Triassic fields located in the Oued Mya basin which are generally small and in direct contact with the Silurian source rock in the basin, (2) the broad low-relief structural traps developed in the Cambro-Ordovician quartzite reservoirs on the adjoining El-Agreb-Hassi Messaoud ridge, 50 to 60 km east of the Oued Mya basin. Utilising conventional biomarker facies and maturity parameters and aromatic hydrocarbons, it is shown that all the oils from the Devonian, the Lower Triassic and the Cambrian fields across the whole petroleum system are similar to the Silurian source rock strata which are widely recognised to be the main source in the region. The oils in the study area are discriminated into three main groups; I) oils from the Hassi Messaoud, Hassi Guettar and El-Agreb fields located in the Hassi Messaoud ridge, II) oils from the Devonian and the Lower Triassic fields located in the Oued Mya basin and III) oils from El-Baguel and Mesdar Cambrian fields. The oils from the El-Baguel and Mesdar Cambrian fields are believed to be generated from the Silurian source rocks located in the Berkine basin, east of the Hassi Messaoud ridge. The biomarker and aromatic hydrocarbon maturity parameters as well as the pyrrolic nitrogen compounds (alkylcarbazoles and benzocarbazoles) data suggest that the oils from Mokh-El-Kebch, N'goussa, Guellala northeast, Guellala and Draa Temra Triassic fields have undergone the least migration distances and were predominantly charged vertically from the underlying Silurian source rocks which are in direct contact with the Devonian and the Lower Triassic reservoirs. The oils from the Haoud Berkaoui and the Benkahla fields appear to have experienced both vertical followed by lateral migration (probably —20 km). Charging of the Hassi Messdoud reservoirs occurred predominantly from the west-northwest and east sectors. The oil experienced long lateral migration distances (40-60 km) starting from the Silurian source rock strata in the northeast of the Oued Mya basin and the Silurian source rock strata located around the Dzabat area east of the field. Once in the Hassi Messaoud reservoirs, the oil migrated upwards towards the crest located in the centre, then downwards to the north, south and finally west parts of the field. Charging of the Hassi Guettar and El-Agreb fields occurred from the north (i.e. from the Hassi Messaoud field). It seems that El-Agreb oils have experienced the longest migration distances across the whole petroleum system (120 to 140 km). Finally, the charging of the Mesdar and El-Baguel fields took place laterally from the southsoutheast starting from the Silurian source likely located in the Berkine basin east of the Hassi Messaoud ridge. The oil in the El-Baguel field seems to have experienced longer migration distance then the oil from the Mesdar field. The study of the petroleum fluid inclusions in the Hassi Messaoud field revealed a reasonable model of temperature and charge history of the Hassi Messaoud field. The modelling results suggest that the Hassi Messaoud sandstone member was at a depth of 2.8 to 3.3 km during the time of petroleum migration into the reservoirs and petroleum inclusion formation. The temperature range at this depth was between 106°C to 118°C from Late Cretaceous to Palaeogene. The distribution of biomarkers and aromatic hydrocarbons in the palaeo-oils extracted from the petroleum inclusions in 6 samples from Hassi Messaoud field and 1 sample from Haoud Berkaoui field revealed that: (1) the palaeo-oils trapped in petroleum inclusions of both fields and the present-day produced oils are similar, likely generated from the Silurian, main source rocks in the region; (2) the palaeo-oils are less mature than the present-day produced oils; and (3) the palaeo-oil trapped in the Haoud Berkaoui Triassic reservoir is even less mature than the palaeo-oils trapped in the Hassi Messaoud reservoirs which may suggest an earlier oil charging of the Haoud Berkaoui field compared to the charging of the Hassi Messaoud field.

No description available.

A suite of samples consisting of twenty-two crude oils and eight sedimentary rocks has been analysed for biological marker compounds by GC-MS. The sedimentary rocks are rich in carbonate minerals and the crude oils were reported to have been derived from carbonate source rocks. These samples are from a variety of geographical origins, geological ages and depositional environments. They consistently contain a homologous series of 30-nor-17 [alpha] (H)-hopanes. Seven homologues (C28 - C34) of the 30-nor-17 [alpha](H)-hopane series have been identified. These compounds appear to be useful biological markers for samples having carbonate associations.A series of 25,30-bisnor-17 [alpha] (H)-hopanes has been observed in a severely biodegraded crude oil of probable carbonate origin. This observation, together with the well-established enrichment of normal hopanes demethylated at position 25 in severely biodegraded crude oils, suggests that the presence of this series of hopanes indicates severe biodegradation of crude oils originating from carbonate-rich source rocks.Another series of hopanes which was previously unreported, the 2-methyl-30-nor-1 [alpha] (H)-hopanes, has also been observed in the carbonate samples. Seven members (C29-C35) of this homologous series have been identified in this study. This series appears to be associated with carbonate rocks deposited under extreme reducing conditions.The biological marker compounds in another sample suite comprising twelve sediments and three crude oils from the North Sumatra Basin, Indonesia, have also been analysed by GC-MS as part of a correlation study. Sediment samples classified as shales, carbonaceous shales and calcareous shales have been shown to contain very different biomarkers. These distinctive biomarkers have enabled the source characteristics of the crude oils to be inferred. Two crude oils have been recognised ++ / with similar biomarker characteristics to the shales and one crude oil has the characteristics of the calcareous shale. The distinctive features of the carbonaceous shale were not observed in the crude oils. This study therefore provides an excellent example of how the 30-nor-17 [alpha] (H)-hopane compounds can be useful in oil-source rock correlation studies.

Igneous intrusion can change the geochemical and petrographic properties of sedimentary organic matter (such as coals and organic-rich clays or shales) including vitrinite reflectance, maceral petrographic composition, mineralogy, stable isotope composition, trace element composition, and bulk geochemistry. Igneous intrusions into coals and organic-rich rocks may have contributed to global warming in the geologic past by causing the release of greenhouse gases. Evidence for the release of large amounts of thermogenic CH4 from the organics would include significant;13Corg enrichment in the residual organic matter. However, 13Corg of thermally altered organic matter in coals and shales adjacent to intrusions often show negative shifts and, in some cases, ambiguous or positive trends. Previous studies have evaluated 13Corg of bulk samples rather than that of individual components, or macerals. As different macerals have different isotopic compositions, maceral-specific trends may be masked by variations in maceral composition of the whole-coal samples. It is important to explain the evolution of different geochemical and petrographic signatures in coals, coals macerals, and organic-rich sedimentary rocks close to an intrusion. This study evaluates the following three hypotheses: (1) thermally altered coals show different geochemical trends compared with coals that have undergone normal burial maturation; (2) if a large-scale release of 13C-depleted thermogenic CH4 resulted from intrusion of the coal, then it should have produced 13C-enriched coal and vitrinite macerals (the most abundant components of the coal) adjacent to the intrusion due to the release of light gases; and (3) 13Corg gets heavier with the increase in heat alteration approaching an intrusion due to the release of isotopically light gases. The current study reports petrographic, bulk geochemical (proximate, and ultimate), 13Corg data (whole-coal/shale samples and vitrinite macerals separated via density-gradient centrifugation, (DGC)), density data (vitrinite macerals), and Rock-Eval pyrolysis data for occurrences of thermally altered Springfield (No. 5) Coal (Pennsylvanian), Danville (No. 7) Coal (Pennsylvanian), and an organic-rich shale in the southern part of the Illinois Basin. Petrographic analysis shows an increase in vitrinite reflectance (Rm) from background levels of 0.55% up to ~4.80% in the Springfield (No. 5) Coal, 0.66% to 4.40% in the Danville (No. 7) Coal, and 0.71% to 4.78% for organic-rich shale; a loss of liptinite macerals, formation of isotropic coke and, at the intrusion contact, even development of fine-grained mosaic anisotropic coke texture. Volatile matter (VM) content decreases and fixed carbon (FC) content, ash, and mineral matter increase approaching the coal/intrusion contact. Carbon increases whereas nitrogen, hydrogen, and oxygen decrease approaching the intrusions. The presence of carbonate minerals (confirmed by X-ray diffraction and petrographic analysis) has a significant impact on proximate and ultimate data. However, even after removal of carbonates, trends for VM vs. vitrinite reflectance, %C vs. Rm, and H vs. C do not follow typical trends associated with normal burial coalification. Approaching the contacts, free oil content (S1), remaining hydrocarbon potential (S2), carbon dioxide from pyrolysis of the organic matter (S3), and hydrogen (HI) and oxygen (OI) indices decrease whereas thermal maturity (Tmax, ⁰C) increases. In addition, HI vs. VM, S2 vs. Rm, and Tmax vs. Rm diverge from pathways seen in previous studies. Trends in most of the Rock-Eval parameters in the organic-rich shale studied here are less clear due to the degree of variation in organic matter content, but a clear increase in thermal maturity (Tmax, C) is seen. There are no significant changes in 13Corg in the whole-coal samples (WCM) of the Springfield (No. 5) Coal (-25.28 / to -24.88 /), Danville (No. 7) whole coals (-25.37 / to -24.76 /), and in the DGC-separated vitrinites (-25.33 / to -24.96 /) of the Springfield (No. 5) Coal approaching the intrusion. However, the organic-rich shale transect shows a 1.31 / positive shift in 13C (from -25.06 / to -23.87 /) approaching the intrusion. DGC-separated vitrinite densities range from 1.268 g/mL in the unaltered coal to 1.523 g/mL at the coal/intrusion contact. For the vitrinite concentrates, density shows a clear correlation with Rm, %Cdaf, Hdaf, H/C, TOC, and 13Corg. These geochemical data suggest that these coals may have followed a different maturation track because of the geologically rapid heating associated with the intrusive event. It is also suggested here that the natural coke textures produced by such rapid geological heating may differ from those observed for metallurgical cokes produced under standard industrial coking conditions. Typically, in an industrial coke oven, a coal of this initial rank (Ro = ~ 0.6%) would produce an isotropic coke, rather than the fine-grained circular anisotropic coke seen here. The development of this texture may reflect differences due to heating rates or, alternatively, may indicate "pre-heating" of the coal during the intrusion event. Changes in the isotopic signatures are not of a magnitude that would be expected if significant thermogenic CH4 had been generated by the intrusive event. Moreover, there is no petrographic evidence for condensed or immobilized thermal products due to rapid pyrolysis (12C-rich pyrolytic carbon) close to the intrusion. These geochemical and petrographic data suggest there was only minimal CH4 generation associated with the rapid heating of the coals and organic-rich sedimentary rocks by the intrusion. In addition, there is no evidence for 13C-depleted condensed gas or pyrolytic carbon at the intrusion contact that could have moderated the isotopic signature. These data agree with previously reported data from this laboratory (Rahman et al., 2014, in review) and others (Gröcke et al., 2009; Yoksoulian, 2010) that indicate no clear evidence for large-scale CH4 generation due to the rapid heating or igneous intrusion in coals or sedimentary rocks.