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1.
Kerogen is the organic matter in sediments that isneither soluble in common organic solvents nor in hy-drous alkaline solvents[1]. It is the most important or-ganic matter on the earth and regarded as the majorsource of natural gas and petroleum. Being the mac-romolecule, kerogen is not readily to be contaminatedby other organic matter. It is the most reliable indige-nous organic matter in sediments[2]. The structure of kerogen is one of the key sub-jects of organic geochemical studies in…  相似文献   

2.
Aromatic hydrocarbons are generally main distillation of crude oil and organic extract of source rocks. Bicyclic and tricyclic aromatic hydrocarbons can be purified by two-step method of chromatography on alumina. Carbon isotopic composition of individual aromatic hydrocarbons is affected not only by thermal maturity, but also by organic matter input, depositional environment, and hydrocarbon generation process based on the GC-IRMS analysis of Upper Ordovician, Lower Ordovician, and Cambrian source rocks in different areas in the Tarim Basin, western China. The subgroups of aromatic hydrocarbons as well as individual aromatic compound, such as 1-MP, 9-MP, and 2,6-DMP from Cambrian-Lower Ordovician section show more depleted 13 C distribution. The 13 C value difference between Cambrian-Lower Ordovician section and Upper Ordovician source rocks is up to 16.1‰ for subgroups and 14‰ for individual compounds. It can provide strong evidence for oil source correlation by combing the 13 C value and biomarker distribution of different oil and source rocks from different strata in the Tarim Basin. Most oils from Tazhong area have geochemical characteristics such as more negative 13C9-MP value, poor gammacerane, and abundant homohopanes, which indicate that Upper Ordovician source rock is the main source rock. In contrast, oils from Tadong area and some oils from Tazhong area have geochemical characteristics such as high 13C9-MP value, abundant gammacerane, and poor homohopanes, which suggest that the major contributor is Cambrian-Lower Ordovician source rock.  相似文献   

3.
Svetlana  Yessalina  Noriyuki  Suzuki  Hiroyuki  Saito 《Island Arc》2006,15(3):292-303
Abstract   The Sagara oil field is located in the Neogene Kakegawa Basin, close to the Izu collision zone at the junction between the main Japanese Islands and the Izu–Bonin Arc. The Sagara oil field is one of the few oil fields situated in a forearc basin on the Pacific side of Japan and is present in a sedimentary basin with poor oil-generating potential. Several crude oils from Sagara oil field were investigated to infer their origin. Organic geochemical characteristics of Sagara oils showed the influences of light biodegradation, migration-contamination, and migration-fractionation. The maturity levels of Sagara oils evaluated based on abundant alkylnaphthalenes corresponded to 0.9–1.2% vitrinite reflectance. Sagara oils were characterized by significant amounts of higher plant biomarkers, a high pristane/phytane ratio and an absence of organic sulphur compounds, suggesting a siliciclastic source rock deposited under nearshore to fluvial–deltaic environments. Numerous faults and fractures in the active forearc basin provided excellent conduits and facilitated upward migration of light hydrocarbons generated at greater depth in the Kakegawa Basin.  相似文献   

4.
Organosulfur compounds of crude oils and light oils (condensates), collected from ten Chinese petroleumbearing basins and representing different sedimentary environments, were analyzed and identified using a newly-developed GC-AED technique. The results show that the distributions of organosulfur compounds of crude oils from different sedimentary environments are of obvious difference. The crude oils from marine carbonates are rich in organosulfur compounds and those from the source rocks in an ocean-land interchanging facies and a littoral facies have a high abundance of organosulfur compounds, while no or less organosulfur compounds of crude oils from a fresh-water lacustrine facies and a swamp facies were detected in the detectable abundance range of the instrument. This analysis gives a new effective method for oil-source correlation. We also tried to relate the various parameters of benzothiophenic compounds of crude oils with the methane carbon isotope of associated natural gases to discuss the thermoevolutionary degree of crude oils and natural gases.  相似文献   

5.
In this study, we experimentally established the relationship between physical properties, vitrinite reflectance, and microstructure of coal, Taiyuan Formation, Qinshui Basin, China using representative coal samples collected from three different mines via the rock mechanics testing system (MTS). We analyzed the organic macerals, vitrinite reflectance, and microstructure of 11 coal samples using petrography and scanning electron microscopy (SEM). The experimental results suggest that (1) the elastic parameters can be described by linear equations, (2) both P-and S-wave velocities display anisotropy, (3) the anisotropy negatively correlates with vitrinite reflectance, and (4) the acoustic velocities and Young’s modulus are negatively correlated with the volume of micropores. The derived empirical equations can be used in the forward modeling and seismic inversion of physical properties of coal for improving the coal-bed methane (CBM) reservoir characterization.  相似文献   

6.
Taking both eastern Linqing Depression and North Jiangsu Basin as examples, based on geochemical features of immature oils as well as source inputs of hydrocarbons and macerals, it is revealed that a mixed source input of alga bio-lipids and higher plant waxes is a basic characteristic of source material for immature oils in non-marine brackish-saline lacustrine basins. Project supported by the “85–102” Chinese National Key Science and Technology Project and the National Gas Geochemistry Key Laboratory, Lanzhou Institute of Geology, Chinese Academy of Sciences.  相似文献   

7.
Oils from two lacustrine rift basins in east China are thoroughly investigated using geochemical method to understand controls on alkylphenol occurrence and distribution in oils. Oils in the Lujiapu Depression, Kailu Basin are derived from the Cretaceous source rocks, and those in the Dongying De- pression, Bohai Bay Basin, from the Tertiary source rocks. All oils are experienced relatively short distance of migration and have similar maturity in each basin. Differences in homologue distributions from different oilfields are most likely caused by organic facies variation of source rocks. The oils in the Lujiapu Depression are characterized by high proportion of C3 alkylphenols (prefixes refer to the number of alkylcarbons joined to the aromatic ring of the phenol molecule) and low proportion of cre- sols and C2 alkylphenols compared to oils from the Dongying Depression. Alkylphenol isomer distri- bution is possibly affected by depositional environment especially for C3 alkylphenols. Dysoxic fresh- water environment is favorable for the formation of propyl or isopropyl substituted C3 alkylphenols, while highly reducing saline water is more suitable for trimethyl substituted C3 alkylphenols. Variations in alkylphenol concentrations within a petroleum system are controlled mainly by secondary migration processes with alkylphenol concentrations decreasing along migration direction. Interestingly, coupled with geological factors, a subtle change of alkylphenol concentrations can be applied to differentiate carrier systems. When oil migrates through sandy beds, concentrations of total alkylphenols decrease dramatically with migration distance, while such change is less significant when oil migrates vertically along faults. However, most isomer ratios potentially related to migration distance are not as effective as those alkylcarbazoles in migration diagnosis due to complicated affecting factors.  相似文献   

8.
Utilizing basic principles and methodologies of geology and organic geochemistry, kinetics of hydrocarbons generation and accumulation, quantitative assessment of crude oils sourced from different source rocks, and hydrocarbons migration pathways for the oils from the Bamianhe Oilfield, the Bohai Bay Basin, Eastern China are discussed. Results of oil-rock correlation showed that the oils were mainly derived from Es4 member (with buried depth >2700 m) of Niuzhuang and Guangli Sags within normal oil window though there is a little amount of mixed immature oils. Quantification of mixed oils with different sources indicated that mature oils account for about 80% of the total oils discovered and immature oils for only 20%. Migration of the oils sourced from the sags is controlled by predominant hydrocarbons migration passages determined by faults, unformalities and favored sandstone reservoir. Results of the origin and migration models for the oils have been recently further testified by considerable quantity of oils discovered in the Bamianhe area, which is obviously playing an important role in guiding further oil exploration.  相似文献   

9.
Since the Meso-Cenozoic, controlled by paleoclimate, a series of fresh to brackish water basins and salt to semi-salt water basins were developed in wet climatic zones and in dry climate zones in China, respectively[1]. The geological and geochemical char…  相似文献   

10.
Absolute concentration of normal alkanes (n-alkanes) and aromatic hydrocarbons in bitumen extracted from source rocks in the period of thermodegradation from Turpan-Hami Basin suggests that aromatic hydrocarbons are dominant in coal and carbargilite while n-alkanes are dominant in mudstones. Bulkrock analysis and gas chromatograph/mass spectrum (GC-MS) of source rocks shows aromatic hydrocarbons are dominant in total ion chromatograms (TIC) of samples with poor perhydrous macerals while n-alkanes are dominant in TICs of samples with abundant perhydrous macerals. The identification of oil-prone and gas prone property based on GC-MS of bitumen “A” together with bulkrock analysis indicates that source rocks from Shengbei area are more oil-prone while source rocks from Qiudong and Xiaocaohu areas are more gas-prone, coinciding with the distribution of oil and gas reservoirs in Taibei Sag. Ratios used to identify oil-prone and gas-prone property for source rocks from Turpan Basin are proposed: n-alkanes >110 μg·mg?1, aromatics <15 μg·mg?1, and n-alkanes/aromatics >8 for oil-prone source rock bitumen while n-alkanes <82 μg·mg?1, aromatics >40 μg·mg?1, and n-alkanes/aromatics <1.5 for gas-prone source rock bitumen.  相似文献   

11.
针对塔里木盆地库车坳陷北部侏罗系烃源岩受泥浆污染、分析数据少、样品分布不连续及类型多样等问题突出,利用测井资料来对有机地球化学参数进行评价难度大,无法满足勘探需求.本文阐述了不同类型烃源岩的有机质级别、测井响应特征、有机地球化学参数定量计算及品质评价等多种方法,来研究富集区烃源岩对致密气储层的持续供气能力.文中介绍了煤层、碳质泥岩、暗色泥岩等3种类型烃源岩的有机质级别和测井响应特征.首先,提出分不同岩性烃源岩的ΔlogR法,其计算结果与铀曲线相关法、多元回归法对比,效果最好;再次建立了生烃潜率、氯仿沥青“A”及镜质体发射率等多个有机质地球化学参数的测井评价模型;最终,考虑能够反映烃源岩性质的参数来综合定义烃源岩品质指数,形成了完善的烃源岩测井综合评价方法研究技术.研究表明,利用这套地球物理技术提供了烃源岩定量评价和品质分类研究方法及实际应用案例.  相似文献   

12.
The total organic carbon(TOC)in the marine source rock of the Ordos Basin mostly ranges from 0.2%to 0.5%.The industrial standard commonly states that the TOC value has to be no less than 0.5%(0.4%for high mature or over-mature source rock)to form large petroleum reservoirs.However,gas source correlation indicates that the natural gas in the Jingbian gas field does receive contribution from marine source rocks.In order to determine the effect of carboxylate salts(or called as organic acid salts)on TOC in highly mature source rocks with low TOC value,we sampled the Ordovician marine source rock and the Permian transitional facies source rock in one drilled well in the southern Ordos Basin and performed infrared and GC-MS analysis.It is found that both kerogen-derived organic acids and carboxylate salt-conversed organic acids exist in both marine and transitional facies source rocks.The carboxylate salt-conversed organic acids mainly come from the complete acidification of carboxylate salts,which confirms the presence of carboxylate salts in the marine source rocks.Although the C16:O peak is the main peak for the organic acids both before and after acidification,the carboxylate salt-conversed organic acids have much less relative abundance ahead of C16:O compared with that of the kerogen-based and free organic acids.This observation suggests that the kerogen-based and free organic acids mainly decarboxylate to form lower carboxylic acids,whereas the carboxylate salt-conversed organic acids mainly break down into paraffins.By using calcium hexadecanoate as the reference to quantify the kerogen-derived and carboxylate salt-conversed organic acids,the high TOC(>2.0%)marine source rocks have low carboxylate salt content and the low TOC(0.2%–0.5%)marine source rocks contain high content of carboxylate salt.Therefore,for the marine source rocks with 0.2%–0.5%TOC,the carboxylate salts may be a potential gas source at high maturity stage.  相似文献   

13.
The Junggar Basin is one of the largest and most petroliferous superimposed petroleum basins in China. The central depression area has become the frontier field for petroleum exploration. The characteristics of potential source rocks and reservoir sandstones, and the pressure regime in the central Junggar Basin were studied. Permian shales are dominated by hydrogen-rich, oil-prone algal organic matter, and Jurassic mudstones are dominated by hydrogen-poor, higher-plant derived organic matter. These source rocks are widespread and have been mature for hydrocarbon generation, suggesting good to excellent exploration potential, both for crude oils and for natural gases. The deeply buried Jurassic sandstones usually have low porosity and permeability. However, sandstones beneath the Jurassic/Cretaceous unconformity display relatively high porosity and permeability, suggesting that meteoric water leaching had improved the quality of the sandstones. Overpressure developed over much of the central Junggar Basin. The overpressured rocks are characterized by slightly increased interval transit time, low sandstone permeability, increased organic matter maturity, and high relative hydrocarbon-gas contents. Mudstones in the overpressured system have quite the same clay mineral compositions as mudstones in the lower part of the normally pressured system. Overpressure generation in the central Junggar Basin is best to be explained as the result of hydrocarbon generation and fluid retention in low-permeability rocks. Petroleum generated from Permian and Jurassic source rocks could migrate laterally through preferential petroleum migration pathways and accumulated in structural traps or lithological traps in the overpressured system, or migrate vertically through faults/hydraulic fractures into the overlying, normally pressured system and accumulate in structural or lithological traps. Therefore, commercial petroleum reservoirs could be potentially found in both the overpressured system, and in the normally pressured system.  相似文献   

14.
Based on GC-MS testing data of many saturated hydrocarbon samples, 17α(H)-C30 diahopanes (C30 *) are extensively distributed in the lacustrine hydrocarbon source rocks of the Yanchang Formation in Ordos Basin, but show remarkable differences in relative abundance among various source rocks. Generally, Chang 7 high-quality source rock (oil shale) developed in deep lake anoxic environment shows lower C30 * content, whereas Chang 6–9 dark mudstone developed in shallow to semi-deep lake, sub-oxidizing environment shows relatively high to high C30 * value. Particularly, Chang 7 and Chang 9 black mudstones in Zhidan region in the northeast of the lake basin show extremely high C30 * value. A comparative analysis was made based on lithology, organic types and various geochemical parameters indicative of redox environment, and the results indicate that environmental factors such as redox settings and lithology are key factors that control the C30 * relative abundance, while organic types and maturity may be minor factors. High to extremely high C30 * values are indicative of sub-oxidizing environment of fresh-brackish water and shallow to semi-deep lake. Therefore, research on C30 * relative content and distribution in lacustrine hydrocarbon source rocks in the Yanchang Formation, especially on the difference in C30 * between Chang 7 high-quality source rocks (oil shale) and Chang 6–91 source rocks (dark mudstone), will provide an important approach for classification of Mesozoic lacustrine crudes and detailed oil-source correlation in the basin. Supported by National Natural Science Foundation of China (Grant No. 40773028)  相似文献   

15.
It is a challenge to determine the source and genetic relationship of condensate, waxy and heavy oils in one given complicated petroliferous area, where developed multiple sets of source rocks with different maturity and various chemical features.The central part of southern margin of Junggar Basin, NW China is such an example where there are condensates, light oils, normal density oils, heavy crude oils and natural gases. The formation mechanism of condensates has been seriously debated for long time;however, no study has integrated it with genetic types of waxy and heavy oils. Taking the central part of southern margin of Junggar Basin as a case, this study employs geological and geochemical methods to determine the formation mechanism of condensates,waxy and heavy oils in a complicated petroliferous area, and reveals the causes and geochemical processes of the co-occurrence of different types of crude oils in this region. Based on detailed geochemical analyses of more than 40 normal crude oils, light oils,condensates and heavy oils, it is found that the condensates are dominated by low carbon number n-alkanes and enriched in light naphthenics and aromatic hydrocarbons. Heptane values of these condensates range from 19% to 21%, isoheptane values from1.9 to 2.1, and toluene/n-heptane ratios from 1.5 to 2.0. The distribution of n-alkanes in the condensates presents a mirror image with high density waxy crude oils and heavy oils. Combined with the oil and gas-source correlations of the crude oils, condensates and natural gas, it is found that the condensates are product of evaporative fractionation and/or phase-controlled fractionation of reservoir crude oils which were derived from mature Cretaceous lacustrine source rocks in the relatively early stage. The waxy oils are the intermediate products of evaporative fractionation and/or phase-controlled fractionation of reservoir crude oils, while the heavy oils are in-situ residuals. Therefore, evaporative fractionation and/or phase-controlled fractionation would account for the formation of the condensate, light oil, waxy oil and heavy oil in the central part of southern margin of Junggar Basin, resulting in a great change of the content in terms of light alkanes, naphthenics and aromatics in condensates, followed by great uncertainties of toluene/n-heptane ratios due to migration and re-accumulation. The results suggest that the origin of the condensate cannot be simply concluded by its ratios of toluene/n-heptane and n-heptane/methylcyclohexane on the Thompson's cross-plot, it should be comprehensively determined by the aspects of geological background, thermal history of source rocks and petroleum generation,physical and chemical features of various crude oils and natural gas, vertical and lateral distribution of various crude oils in the study area.  相似文献   

16.
Nitrogen occupies a high content in crust and in atmospheric circle. It is one of the main elements in organism and an important element in sedimentary circle. Although nitrogen is little in crude oil, to a cer-tain degree, it influences the physical and chemical properties of oil, such as viscosity and density[1]. In reservoir the nitrogen-bearing compounds can form ion bonds or hydrogen bonds with substances on rock and form van der Vaals’ force among moleculae so they affect and alter the …  相似文献   

17.
The crude oils typically from the CambrianLower Ordovician source rocks of Tarim Basin, NW"China, such as TD2 and TZ62S, are13C-enriched with the stable carbon isotopic ratios(VPDB) approaching-28 %.In this paper, the main research viewpoints on this issue are summarized, and combined with results from organic and inorganic carbon isotope stratum curves of the outcrop at the Ya'erdang Mountain in Tarim Basin. In addition, more alternative interpretations are discussed. On one hand, the inverse fractionation features of stable carbon and hydrogen isotopes of these crude oils may imply their protogenous nature. On the other hand, the anisotropy of source rocks and contribution from older stratum source rocks need verifying as well. For the sake of the final resolution of this issue, some further study topics are recommended.  相似文献   

18.
Whether benthic macroalga can be an important type of bio-precursor of source rocks is a contentious issue in source-rock studies, and has not been well understood. This paper represents a case study of Jurassic mudstone source rocks from the northern Qaidam Basin, northwestern China, in which the benthic macro red algae were recognized for the first time based on combined organic petrological and biomarker works. We found not only cystocarps in the algae, representative of rhodophyta, but also diahopanes, which are diagnostic biomarkers of such algae. Thus, as many reservoired oils in the northern Qaidam Basin contain abundant diahopanes, it may indicate that the red algae have contributed to hydrocarbon accumulation. This was confirmed by integrated geological and geochemical analyses. Hence, this study provides new evidence for macroalga-generated hydrocarbons. Supported by National Natural Science Foundation of China (Grant Nos. 40602014, 40872086, 40638042)  相似文献   

19.
利用自由基浓度研究盆地古地温的方法   总被引：1，自引：0，他引：1       下载免费PDF全文
主要讨论了利用自由基浓度研究盆地古地温的三种方法，并结合实测的自由基浓度值估算了塔里木盆地ＴＺ１井的古地温梯度和反演了琼东南盆地单井的热流变化历史．  相似文献   

20.
Eiji Sasao 《Island Arc》2013,22(2):170-184
A petrographic study of sandstones from the Miocene Mizunami Group in Central Japan has been performed on core samples from a single borehole, in order to evaluate the provenance of the sedimentary rock. Evaluation of the provenance is based on bulk mineral, heavy mineral and plagioclase contents and on whole rock chemical compositions. The sandstones studied are divisible into three types; the first type is characterized by the occurrence of biotite and plagioclase ranging from albite to oligoclase, the second type is characterized by the dominance of amphibole and labradorite with pyroxene (clinopyroxene > orthopyroxene), and the third type is characterized by the dominance of pyroxene (orthopyroxene > clinopyroxene) and andesine with lesser labradorite, bytownite and anorthite. The first type is interpreted to be derived from the basement granite, whereas the others were derived mostly from volcanic ash, judging from their mineral compositions. The volcanic activity that supplied the volcanic ash to the Mizunami Basin occurred in two phases, distinguishable by variations in their mineralogical and geochemical compositions, an indication of change in character of the volcanic activity. This petrographic study of the sandstones in the Mizunami Group suggests that unrecognized volcanic activity occurred around the Mizunami Basin, even though potential provenance of the volcanic ash has not yet been identified.  相似文献   

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