Organic Petrology of Potential Source Rocks in the Tarim Basin, Nw China

Liu, Dameng; Tu, Jian; Kuili, Jin

doi:10.1111/j.1747-5457.2003.tb00020.x

Cited by 12 publications

(6 citation statements)

References 8 publications

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“…Jurassic−Triassic coals and coaly shales in the Tarim Basin are mostly gas-prone. Vitrinite and inertinite constitute most of the structural macerals, with inertinite averaging about 33% . In constrast, the oil-prone type IIIC kerogens in our study are mainly (∼90%) composed of perhydrous vitrinite with minor amounts of exinite.…”

Section: Discussionmentioning

confidence: 54%

Direct Characterization of Kerogen by X-ray and Solid-State ¹³C Nuclear Magnetic Resonance Methods

Kelemen¹,

Afeworki²,

Gorbaty³

et al. 2007

Energy Fuels

448

449

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A combination of solid-state 13C NMR, X-ray photoelectron spectroscopy (XPS) and sulfur X-ray absorption near edge structure (S-XANES) techniques are used to characterize organic oxygen, nitrogen, and sulfur species and carbon chemical/structural features in kerogens. The kerogens studied represent a wide range of organic matter types and maturities. A van Krevelen plot based on elemental H/C data and XPS derived O/C data shows the well established pattern for type I, type II, and type III kerogens. The anticipated relationship between the Rock−Eval hydrogen index and H/C is independent of organic matter type. Carbon structural and lattice parameters are derived from solid-state 13C NMR analysis. As expected, the amount of aromatic carbon, measured by both 13C NMR and XPS, increases with decreasing H/C. The correlation between aromatic carbon and Rock−Eval T max, an indicator of maturity, is linear for types II and IIIC kerogens, but each organic matter type follows a different relationship. The average aliphatic carbon chain length (Cn‘) decreases with an increasing amount of aromatic carbon in a similar manner across all organic matter types. The fraction of aromatic carbons with attachments (FAA) decreases, while the average number of aromatic carbons per cluster (C) increases with an increasing amount of aromatic carbon. FAA values range from 0.2 to 0.4, and C values range from 12 to 20 indicating that kerogens possess on average 2- to 5-ring aromatic carbon units that are highly substituted. There is basic agreement between XPS and 13C NMR results for the amount and speciation of organic oxygen. XPS results show that the amount of carbon oxygen single bonded species increases and carbonyl−carboxyl species decrease with an increasing amount of aromatic carbon. Patterns for the relative abundances of nitrogen and sulfur species exist regardless of the large differences in the total amount of organic nitrogen and sulfur seen in the kerogens. XPS and S-XANES results indicate that the relative level of aromatic sulfur increases with an increasing amount of aromatic carbon for all kerogens. XPS show that the majority of nitrogen exists as pyrrolic forms in comparable relative abundances in all kerogens studied. The direct characterization results using X-ray and NMR methods for nitrogen, sulfur, oxygen, and carbon chemical structures provide a basis for developing both specific and general average chemical structural models for different organic matter type kerogens.

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Section: Discussionmentioning

confidence: 54%

Direct Characterization of Kerogen by X-ray and Solid-State ¹³C Nuclear Magnetic Resonance Methods

Kelemen¹,

Afeworki²,

Gorbaty³

et al. 2007

Energy Fuels

448

449

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“…Paired flexural basins developed to the north and south of the ancestral Tian Shan, in response to regional north‐south regional contraction and uplift within the Tian Shan region (Hendrix et al , 1992). Fluvial sandstone and conglomerate were deposited adjacent to the Tian Shan and Bogda Shan (Hendrix et al , 1992; Greene et al , 2001a, b), but Upper Triassic freshwater lacustrine deposits and coal have been reported in the basin interiors (Zhai et al , 1987; Zou et al , 2003; Liu et al , 2003; Zhao et al , 2005)…”

Section: Nonmarine Sedimentary Basin Evolutionmentioning

confidence: 99%

Walled sedimentary basins of China

2010

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Central Asia contains numerous closed geomorphic basins that are surrounded by active mountain ranges, but exhibit little internal deformation.These areas commonly coincide with sedimentary basins that record a much older history of continuous internal drainage, evidenced by lacustrine and associated alluvial deposits that date as back far as the Late Permian.We propose the new descriptive term 'walled basin' , in recognition of the unique physiography of basins that impound sediments within peripheral orogenic walls that are maintained over relatively long geologic time scales.Walled basins are surrounded by dominantly contractional orogenic uplifts, but are themselves relatively undeformed.They typically record multiple episodes of alluvial and lacustrine sedimentation, that are often correlated with evidence for recurrent deformation of basin-bounding uplifts.The distribution of walled basins in Asia appears to correspond to crustal heterogeneities inherited from the complex accretionary history of the continent, but actual mechanisms for maintaining stable basin interiors over periods as long as $250 my remain uncertain. Modern walled basins in Asia are restricted to arid or semiarid regions, due to the capacity of large rivers to defeat drainage barriers in more humid areas.Walled basins lie at lower elevations than Asia as whole, and they appear to impede rather than promote plateau growth.Contractile deformation continued in western China from the latest Jurassic to Early Cretaceous. Contraction and renewed uplift of theTian Shan during this time broadly coincided with collision of the Lhasa block to the south, and r

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“…Lower Paleozoic source rocks in the Tazhong area include Lower -Middle Cambrian and Middle -Upper Ordovician strata Liu et al, 2003). The Lower-Middle Cambrian source rocks matured and began to generate hydrocarbons during the Caledonian orogeny (Liu, 1998;Zhang et al, 2000a).…”

Section: Petroleum Accumulation In the Tazhong 45 Reservoirmentioning

confidence: 99%

Hydrothermally Fluoritized Ordovician Carbonates as Reservoir Rocks in the Tazhong Area, Centraltarim Basin, Nw China

Jin

Zhu

Zhang

et al. 2006

Journal of Petroleum Geology

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Reservoir rocks at the Tazhong 45 oil pool, central Tarim Basin, consist of fluoritized carbonate strata of Middle -Late Ordovician age. Petrological observations indicate that the fluorite replaces calcite. Several other hydrothermal minerals including pyrite, quartz, sphalerite and chlorite accompany the fluorite.Two generations of fluid inclusions are present in the fluorite. Homogenization temperatures (Th) for primary inclusions are mostly between 260°C and 310°C and represent the temperature of the hydrothermal fluid responsible for fluorite precipitation. Th for secondary inclusions range from 100°C to 130°C, and represent the hydrocarbon charging temperature as shown by the presence of hydrocarbons trapped in some secondary inclusions. The mineral assemblage and the homogenization temperatures of the primary fluid inclusions indicate that the precipitation of fluorite is related to hydrothermal activity in the Tazhong area. Strontium isotope analyses imply that the hydrothermal fluids responsible for fluorite precipitation are related to late-stage magmatic activity, and felsic magmas were generated by mixing of mafic magma and crustal materials during the Permian.Theoretical calculations show that the molecular volume of a carbonate rock decreases by 33.5% when calcite is replaced by fluorite, and the volume shrinkage can greatly enhance reservoir porosity by the formation of abundant intercrystalline pores. Fluoritization has thus greatly enhanced the reservoir quality of Ordovician carbonates in the Tazhong 45 area, so that the fluorite and limestone host rocks have become an efficient hydrocarbon reservoir. According to the modelled burial and thermal history of the Tazhong 45 well, and the homogenization temperatures of secondary fluid inclusions in the fluorite, hydrocarbon charging at the Tazhong 45 reservoir took place in the Tertiary. Plate 1 (left). Photographs of hydrothermal minerals and hydrocarbons in wellTazhong 45 cores: A. Fluorite vein in limestone at 6,081.2m, fluorite replaces limestone; B. Chert and fluorite at 6,101.2m; C. Fluorite at 6,106.8m (partially cross polarized light); D. Fluorite and calcite at 6,106.8m (plane polarized light); fluorite replaces calcite and there are more intercrystalline cavities in the fluorite than in the calcite. E. Remnant calcite and quartz in fluorite at 6,106.8m (cross polarized light); F. Hydrocarbons in microfractures in fluorite at 6,106.8m, UV epifluorescence; G. Chert at 6,101.2m (plane polarized light); H. Quartz and fluorite at 6,100.5m, quartz is deposited among the fluorite (plane polarized light); I. Hydrothermal fractures at 5,298.0m filled with pyrite contemporaraneously precipitated from the hydrothermal fluid (reflected light); J. Sphalerite and chlorite in well Tazhong 12, 5,217.0m, core photograph; K. Sphalerite in well Tazhong 12, 5217.0m, EPMA secondary electron image. Plate 2 (above). Primary and secondary fluid inclusions in fluorite in well Tazhong 45. A, B. Primary fluid inclusions (transmitted light) at 6,100.9m and 6,104.2m, ...

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Organic Petrology of Potential Source Rocks in the Tarim Basin, Nw China

Cited by 12 publications

References 8 publications

Direct Characterization of Kerogen by X-ray and Solid-State ¹³C Nuclear Magnetic Resonance Methods

Direct Characterization of Kerogen by X-ray and Solid-State ¹³C Nuclear Magnetic Resonance Methods

Walled sedimentary basins of China

Hydrothermally Fluoritized Ordovician Carbonates as Reservoir Rocks in the Tazhong Area, Centraltarim Basin, Nw China

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Organic Petrology of Potential Source Rocks in the Tarim Basin, Nw China

Cited by 12 publications

References 8 publications

Direct Characterization of Kerogen by X-ray and Solid-State 13C Nuclear Magnetic Resonance Methods

Direct Characterization of Kerogen by X-ray and Solid-State 13C Nuclear Magnetic Resonance Methods

Walled sedimentary basins of China

Hydrothermally Fluoritized Ordovician Carbonates as Reservoir Rocks in the Tazhong Area, Centraltarim Basin, Nw China

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Direct Characterization of Kerogen by X-ray and Solid-State ¹³C Nuclear Magnetic Resonance Methods

Direct Characterization of Kerogen by X-ray and Solid-State ¹³C Nuclear Magnetic Resonance Methods