COMPARISON OF SELECTED NON-MARINE PETROLEUM-BEARING BASINS IN AUSTRALIA AND CHINA

1986 ◽  
Vol 26 (1) ◽  
pp. 285
Author(s):  
P.S. Moore D.K. Hobday H. Mai ◽  
Z.C. Sun
Keyword(s):  
Ordos Basin ◽  
Sedimentary Facies ◽  
Alluvial Fan ◽  
Source Rocks ◽  
Local Source ◽  
Type I ◽  
Migration Routes ◽  
Factors Affecting ◽  
Half Graben ◽  
Oil Source

This paper summarises the geology and hydrocarbon potential of two Chinese and two Australian basins (Ordos, Northern Jiangsu, Eromanga, and Surat basins) in order to compare factors affecting the generation, migration, and entrapment of hydrocarbons. In all four basins, hydrocarbons are generated from nonmarine source rocks of lacustrine and fluvial-overbank origin. While the Chinese and Australian basins contain a similar range of sedimentary facies, from alluvial fan to lacustrine, the arrangement and relative thicknesses of these facies vary considerably as a result of different tectonic and palaeoclimatic settings.During the Triassic, the Ordos Basin was dominated by retroarc foredeep subsidence and the development of deep, fresh-water lakes with anoxic bottom waters. This non-bioturbated substrate, with Type I and II kerogen precursors, provided an excellent oil source for adjacent fan-delta, deltaic, and fluvial reservoirs, and for the unconformably overlying Jurassic fluvial valley-fill sandstone reservoirs.The Northern Jiangsu Basin was initiated by back-arc extension and underwent very rapid half-graben subsidence in the Eocene. Alluvial fan, shoreline, and fluvial facies aggraded in a relatively narrow zone along the active, faulted margin, and merged laterally into organic-rich shales which provided a local source for oil.By comparison, the Eromanga/Surat basins developed in response to gentle downwarp and reactivation of older structural trends. Reservoirs are largely restricted to craton-derived quartzose facies such as in the Hutton, Precipice, and Namur sandstones. There is probably a dual source for oil, from the underlying Permian (which may be the dominant source in the Surat Basin), and from shales deposited in shallow, partly oxygenated lakes and overbank facies of Jurassic age (important in the Eromanga, and possibly subordinate in the Surat Basin). Deep lacustrine facies, typical of the Chinese basins, did not develop. The greater abundance of oil in the Chinese nonmarine basins is explained in terms of tectonic and palaeoclimatic factors which yielded thicker and better quality source rocks, more rapid maturation, and a better juxtaposition of source rocks and good-quality reservoirs, thus providing short, highly efficient migration routes.

Liquid hydrocarbon characterization of the lacustrine Yanchang Formation, Ordos Basin, China: Organic-matter source variation and thermal maturity

2017 ◽  
Vol 5 (2) ◽  
pp. SF225-SF242 ◽  
Author(s):  
Xun Sun ◽  
Quansheng Liang ◽  
Chengfu Jiang ◽  
Daniel Enriquez ◽  
Tongwei Zhang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Source Rock ◽  
Ordos Basin ◽  
Depositional Environments ◽  
Source Rocks ◽  
Type I ◽  
Hydrocarbon Generation ◽  
Type Ii ◽  
Thermal Maturity ◽  
Yanchang Formation

Source-rock samples from the Upper Triassic Yanchang Formation in the Ordos Basin of China were geochemically characterized to determine variations in depositional environments, organic-matter (OM) source, and thermal maturity. Total organic carbon (TOC) content varies from 4 wt% to 10 wt% in the Chang 7, Chang 8, and Chang 9 members — the three OM-rich shale intervals. The Chang 7 has the highest TOC and hydrogen index values, and it is considered the best source rock in the formation. Geochemical evidence indicates that the main sources of OM in the Yanchang Formation are freshwater lacustrine phytoplanktons, aquatic macrophytes, aquatic organisms, and land plants deposited under a weakly reducing to suboxic depositional environment. The elevated [Formula: see text] sterane concentration and depleted [Formula: see text] values of OM in the middle of the Chang 7 may indicate the presence of freshwater cyanobacteria blooms that corresponds to a period of maximum lake expansion. The OM deposited in deeper parts of the lake is dominated by oil-prone type I or type II kerogen or a mixture of both. The OM deposited in shallower settings is characterized by increased terrestrial input with a mixture of types II and III kerogen. These source rocks are in the oil window, with maturity increasing with burial depth. The measured solid-bitumen reflectance and calculated vitrinite reflectance from the temperature at maximum release of hydrocarbons occurs during Rock-Eval pyrolysis ([Formula: see text]) and the methylphenanthrene index (MPI-1) chemical maturity parameters range from 0.8 to [Formula: see text]. Because the thermal labilities of OM are associated with the kerogen type, the required thermal stress for oil generation from types I and II mixed kerogen has a higher and narrower range of temperature for hydrocarbon generation than that of OM dominated by type II kerogen or types II and III mixed kerogen deposited in the prodelta and delta front.

scholarly journals Organic Geochemical Characteristics of Mudstone and Marl from Western Hoh Xil Basin of Tibet

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Wentian Mi ◽  
Xueyuan Qi ◽  
Yan Shang ◽  
Xu Kong ◽  
Zifu Hu
Keyword(s):  
Organic Matter ◽  
Higher Plants ◽  
Organic Geochemistry ◽  
Sedimentary Environment ◽  
Sedimentary Facies ◽  
Alluvial Fan ◽  
Maturity Stage ◽  
Type I ◽  
High Productivity ◽  
Sedimentary Characteristics

The mudstone and marl from western Hoh Xil basin, located in Tibet of the west of China, were deposited in Tertiary lacustrine environment. Investigation of organic geochemistry, sedimentary characteristics, and 13C in kerogen was conducted to analyze the sedimentary environment, biomarkers, paleoclimate, and source of organic matter during deposition. The Cenozoic sedimentary facies of the basin included upper lacustrine facies and lower alluvial fan facies, which belong to Miocene Wudaoliang Formation and Oligocene Yaxicuo Group, respectively. The Miocene marl-sandstone-mudstone from Wudaoliang Formation was analyzed. Maceral composition was dominated by amorphous organic matter. T max values indicated that the mudstones were thermally immature-low maturity with mainly type II and III organic matter, while organic matter in marlite belongs mainly to type I-II1 with low maturity-maturity stage. The biomarkers showed the characteristics of odd-over-even predominance of long-chain n-alkanes, higher proportion of C27 sterane in most of the samples, heavy δ13Corg composition, low Pr/Ph ratios (0.11-0.36), and so on. Organic geochemistry indicated that the organic matter originated from bacteria, algae, and higher plants. The rocks were formed in reducing environments with stratified water column and high productivity. The paleoclimate became more humid during depositional stage in the western Hoh Xil basin.

Petroleum Systems Modeling and Hydrocarbon Migration and Oil Potential Assessment of the Southern Side of Pre-Caspian Basin, Kazakhstan

2021 ◽  
Author(s):  
Dilyara Urmanova
Keyword(s):  
Thermal Model ◽  
Flow Equation ◽  
Carbonate Reservoir ◽  
Source Rocks ◽  
Caspian Basin ◽  
Type I ◽  
Migration Routes ◽  
Geological Time ◽  
Cross Sectional ◽  
And Migration

Abstract An active oil system is recognized from the data in the Tengiz-Primorsky uplift zone of the southern edge of the Pre-Caspian Basin in stratigraphic ascending and structural traps of the Famennian carbonate reservoir. This area is considered one of the most high-yeilding gas provinces in Kazakhstan. However, the timing of the displacement and migration of hydrocarbons depending on the formation of traps remains unclear. To reduce this uncertainty, an attempt was made to analyze a cross-sectional model that takes into account seismic structural interpretation and data from the Ansagan 1 well to simulate history, temperature, sourcerock maturity and pressure regimes over geological time. The displacement of hydrocarbons from the original rocks and further HC migration were modeled using 2D reservoir fluid flow modeling based on the Darcy flow equation. The main blocks of the source rocks correspond to the Devonian complex with the influence of algal lipids or organic matter enriched in lipids (type I kerogen). The maturity trend increases from east to west due to higher burial. The general objectives of this article were to set goals and determine the level of detalization of the research; selection and preparation of input data, filling the model with information, restoring the basin immersion history, calculating the thermal model, and determining the maturity of source deposits, calibrating the thermal model, calculating HC emigration; assessment of migration routes.

scholarly journals Origin and Distribution of Carbonate Cement in Tight Sandstones: The Upper Triassic Yanchang Formation Chang 8 Oil Layer in West Ordos Basin, China

Geofluids ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-13 ◽  
Author(s):  
Jin Lai ◽  
Guiwen Wang ◽  
Jing Chen ◽  
Shuchen Wang ◽  
Zhenglong Zhou ◽  
...  
Keyword(s):  
Organic Acids ◽  
Late Stage ◽  
Ordos Basin ◽  
Source Rocks ◽  
Type I ◽  
Dissolved Carbon ◽  
Carbonate Cement ◽  
Two Generations ◽  
Tight Carbonate ◽  
Ferroan Dolomite

Two generations of carbonate cement as Type I (microcrystalline calcite and dolomite) and Type II (mainly Fe-calcite and Fe-dolomite) are recognized in Chang 8 sandstones, Ordos basin. Carbonate cement in Chang 8 sandstones is closely related to the dissolved carbon from thermal maturation of organic matters. Carbonate cement in the loosely packed framework grains precipitated shortly after deposition, and late-stage ferroan calcite and ferroan dolomite formed with progressive burial. The early diagenetic carbonate cement is partially to completely replaced by late-stage ferroan calcite and ferroan dolomite. Carbonate cement is much more commonly observed in sand bodies adjacent to Chang 7 source rocks. With increasing distance from the Chang 7 oil layers, the carbonate cement content gradually decreases. However, some tight carbonate cemented zones also occur at the sandstone-mudstone interfaces. Dissolution of Ca-feldspars by organic acids-rich fluids, together with clay mineral transformations such as illitization of smectite, would provide Ca2+ and Mg2+ ions for carbonate cementation. Organic acids and CO2 rich fluids would charge into the reservoirs with the hydrocarbons, and when the CO2 and acids were buffered by the framework grain dissolution, carbonate cement would precipitate with a decrease in CO2 concentration.

scholarly journals Climate-Provenance Effect on the Organic Matter Enrichment of the Chang 9 Source Rocks in the Central Ordos Basin, China

Geofluids ◽  
2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Ling Ma ◽  
Zhihuan Zhang ◽  
Weiqiu Meng
Keyword(s):  
Organic Matter ◽  
Chemical Weathering ◽  
Ordos Basin ◽  
Source Rocks ◽  
Sediment Provenance ◽  
Type I ◽  
Hydrocarbon Generation ◽  
Hydrocarbon Generation Potential ◽  
Primary Producer ◽  
Geochemical Analyses

The Upper Triassic Chang 9 organic-rich sediments have been considered as effective hydrocarbon source rocks for the Mesozoic petroleum system in the Ordos Basin. Previous studies on the Chang 9 member mostly focused on the influence of their paleoproductivity and paleoredox conditions on the organic matter (OM) enrichment, whereas there are few studies on the influence of the paleoclimate condition and sediment provenance on the OM enrichment. In this study, a series of geochemical analyses was performed on the Chang 9 core samples, and their hydrocarbon generation potential, paleoclimate condition, and sediment provenance were assessed to analyze the effect of paleoclimate-provenance on OM enrichment. The Chang 9 source rocks are characterized by high OM abundance, type I−II OM type, and suitable thermal maturity, implying good hydrocarbon generation potential. Based on the C-values and Sr/Cu ratios, the paleoclimate condition of the Chang 9 member was mainly semihumid. In addition, the Th/Co vs. La/Sc diagram and negative δEuN indicate that the Chang 9 sediments were mainly derived from felsic source rocks. Meanwhile, the paleoweathering intensity of the Chang 9 member is moderate based on moderate values of CIA, PIA, and CIW, which corresponds to the semihumid paleoclimate. The relatively humid paleoclimate not only enhances photosynthesis of the primary producer, but also promotes chemical weathering intensity, leading to suitable terrestrial clastic influx to the lacustrine basin, which is beneficial for OM enrichment.

scholarly journals Secondary migration of hydrocarbons in the Zhujiang Formation in the Huixi half-graben, Pearl River Mouth Basin, South China Sea

2016 ◽  
Vol 53 (2) ◽  
pp. 189-201 ◽  
Author(s):  
Junwen Peng ◽  
Xiongqi Pang ◽  
Shuang Xiao ◽  
Huijie Peng ◽  
Qianwen Li ◽  
...  
Keyword(s):  
Physical Properties ◽  
River Mouth ◽  
Source Rocks ◽  
Pearl River ◽  
Pearl River Mouth Basin ◽  
Hydrocarbon Migration ◽  
Source Correlation ◽  
Half Graben ◽  
Porosity And Permeability ◽  
Oil Source

The process and mechanisms of secondary hydrocarbon migration in the Huixi half-graben, Pearl River Mouth Basin, were investigated on the basis of geological analysis of the strata and study of the porosity and permeability of the reservoir rocks, fluid potential, oil properties, and geochemistry of oil–source correlation. The results suggest that the hydrocarbons of the Zhujiang Formation in the Huixi half-graben were derived from source rocks of the Eocene Wenchang Formation and the Eocene–Oligocene Enping Formation in the Huizhou Sag. The hydrocarbons migrated laterally from northeast to southwest. The sandstone in the upper member of the Zhujiang Formation exhibited superior physical properties (porosity and permeability) and connectivity than the lower member. Thin sandstone beds with good physical properties and stable distribution in the upper member of the Zhujiang Formation were the main carrier beds for lateral hydrocarbon migration.

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