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1.
碳酸盐矿物的包裹有机质及其生油意义   总被引：5，自引：3，他引：5  
Fluorescent slice observations have revealed a considerable amount of organic matter enclosed in carbonate minerals, most of it giving off yellow-brown fluorescence and being zonally distributed in calcite and dolomite. The amount of enclosed organic matter released from the enclosure when treated with HCl is two times higher than that of extractable organic mattes in the same rock sample. In comparison to the extractable organic matter, the enclosed organic matter is possessed of some compositional characters of its own. In terms of the distribution of biological markess, it is suggested that the enclosed organic matter may be low in maturity relative to the extractable organic matter in the same source rock.Results of the simulating experiments under high temperatures and pressures show that this kind of organic matter enclosed in carbonate minerals can be converted into oil-generating substances. Therefore, detailed studies of the enclosed organic matter are of much help to the evaluation of oil-generating potentiality of carbonate source rocks.  相似文献   

2.
碳酸盐岩生油岩的有机地球化学、岩石学特征   总被引：13，自引：1，他引：13  
Features of oil-generating carbonate rocks are studied in terms of petrology and organic geochemistry of fluorescent materials in rocks. It is postulated by the authors that the organic carbon content in oil-generatlng carbonate rocks is necessarily lower than that in shales, and the possible cause of this observation is discussed. The quality of oil-ganerating carbonate rocks may be judged by aromatic structure index,amino acid, pigment index, and DTA data on organic matter. However, the application of presently available organic geochemical criteria to non-oil-generating reservoir rocks may always give misleading results. To circumvent this difficulty, it is necessary first to make distinction between primary and secondary organic matter by cxamining the fluorescent materials under a fluorescence microscope. Measurementof radical content of the organic substances and DTA are useful techniques to determine the degree of maturation. The maturation of organic substances proceeds at a lower rate in carbonate rocks than in shales. It is likely, therefore, that some older carbonate strata can also be promising areas for petroleum exploration. Oil-generating carbonate rocks consist mainly of mierite limestones rich in organic matter and are thought to be formed under low-encrgy environment. Consequently, petrological(especially mierolithofacies) studies are very important in evaluating carbonate source rocks.  相似文献   

3.
Samples of Continetal shelf sediments from the East China Sea have been studied in an attempt to eluciate the relationship of metallie element enrichment with organoclay complexes. Investigations of the distribution patterns and modes of existence of such elements as Cu, Pb, Zn, Ni, Fe, Mn, etc. in the sediments demonstrate that there exist remarkable positive eorrelations between tha distribution of all elements except for Mn,and the content of clay minerals and organic matter and its type. Experimental results show that the removal of combined organic matter will lead to a rapid decrease in the content of these elements (up to mote than 50%). Organoelay chemistry study indicates that the enrichment of metallic elements in the sediments may involve the following processes: (1) the formation of organic metallic complexes by the ineraction between organic matter and metallic ions in the water body; (2) the production of organoclay complexes by the interaction between the organic metallic complexes and clay minerals in the same medium, (3) the deposition of the organoelay complexes due to the variation of water medium conditions during their migration, thus enabling the sediments to be enriched in some metallic elements. From the above, it can be seen that organoclay complexes may be one of the important forms of existense of metallic elements concentrated in the sediments, and also of significance in eluciating the mechanism of fineralization of metallic elements.  相似文献   

4.
Soluble organic matter had been separated from several palygorskite and bentonite samples in the Ji-angsu-Anhui border area(across Jiangsu Province and Anhui Province) and Linze County in Gansu Province of China and was analyzed with the techniques and methods of organic geochemistry.The composition and distribution of hydrocarbons were analyzed by gas chromatography(GC).Organic stable carbon isotopic ratios(δ13C) in typical samples were determined.The abundance of soluble organic matter in all clay samples analyzed was low.In Ji-angsu-Anhui samples,the preservation states of organic matter are different;hydrocarbons in organic matter have some features of aquatic plankton but are short of the input of terrigenous higher plants;organic δ13C in a palygor-skite of Yongxiaoshan in Xuyi County,Jiangsu Province,is-6.72‰.These features may be typical of a sedimentary environment of closed or semi-closed and relatively isolated different waters near coast or seashore.On the contrary,in samples from Gansu,the preservation states of organic matter are good;the GC graphs of hydrocarbons show that the precursors of the organic matter are from a mixed source of aquatic organisms and land-sourced higher plants;organic δ13C of a palygorskite from Yangtai of Gansu is-15.62‰.It indicated that the sedimentary environment may be an inland salty lake.Preliminary results suggest that palygorskite minerals in the Jiangsu-Anhui area may be evolved from rapidly accumulated fine material or volcanic ash,but clays in Gansu Province may be transformed from terrigenous inorganic clastic components carried to the lake through river and then deposited.The generation process of the samples studied in the paper seems to be related to salty water.  相似文献   

5.
Classic physical and chemical treatments applied to separating clay minerals from the host sediments are often difficult or aggressive for clay minerals. A technique using cation exchange resins (amberlite IRC-50H and amberlite IR-120) is used to separate clay minerals from the host sediments. The technique is based on the exchange of cations in the minerals that may be associated clay minerals in sediments, such as Ca and Mg from dolomite; Ca from calcite, gypsum and francolite with cations carried by resin radicals. The associated minerals such as gypsum, calcite, dolomite and francolite are removed in descending order. Separation of clay minerals using cation exchange resins is less aggressive than that by other classic treatments. The efficiency of amberlite IRC-50H in the removal of associated minerals is greater than that of amberlite IR-120.  相似文献   

6.
Zhong Jianhua 《沉积学报》1997,15(1):128-134
Little is known about the geochemistry of peat and soft-brown coal The analytical chemical dataof forty eight samples have been obtained for the peat and soft-brow n coal in the 7henan basin, western Yunnan. njection of continental detritus into theswamp is favourable for the degradation of plant remains and thefor-oration of humic acid. The oxide compositions of the ash of the peat and soft一)rown coal and their distribution-typeshave indicated that the continental detritusome from two kinds of parent rocks.The Al2O3 and SiO2have a positive correlation with humic acid(Hmz)，showing that the organic matter is ad-vantageous to the formation of aluminosilic;ate mineral(mainly kaolinite, authigenic organic clay minerals). The TiO2 enrichment is mainly related to mineral materials. The Ge content in the peat and soft-brown coalranges from 0. 2- 2.6×10-6, and it is mainly bound to those minerals with Al2O3and organic matters. The GaContent is from 2. 3- 19.1×10-6，and it is associated with minerals that are MgO一Baring aluminosilicate minerals.The uranium (0.3- 4.9×10-6) is mainly bound in the Ca-and Mg-bearing minerals. They are not enriched andnot related to organic matter.  相似文献   

7.
Adsorption experiments were made at room temperature and neutral pH value on different types of min-erals associated with the Lower Cambrian black shale series polymetallic layers in Hunan and Guizhou provinces on nanometer-sized Pt colloids and PtCl42--bearing ionic solutions with an attempt to constrain the relationship between the different types of minerals in the polymetallic layers and the enrichment of platinum group elements (PGEs). Experimental results showed that the different types of minerals show strong selectivity to the adsorption of nano-meter-sized Pt colloids and PtCl42--bearing ionic solutions. Metallic sulfides, organic matter and clay minerals are the strong adsorbents of PGEs, while quartz, albite, muscovite and other silicate minerals show a week adsorbility to both of them. This phenomenon is well consistent with the geological fact that metallic sulfides, organic matter and clay minerals in the polymetallic layers of the black shale series are the major carrier minerals of PGEs, giving a thorough explanation to the mechanism of enrichment of previous metal elements. Adsorption may be a principal mechanism of enrichment of precious metal elements under lower temperature conditions. The presence of the aforementioned strong adsorbents is the good geochemical barriers for the enrichment of PGEs.  相似文献   

8.
The Ni-Mo-PGE polymetallic mineralization of the Lower Cambrian black shales locate in Zunyi, South China and contain abundant noble metals such as Ag, Au and PGE, and especially Ag with average concentration of 64×10-6. The occurrence modes of Ag have been investigated using methods of selective chemical dissolution and transmission electron microscopy. The results demonstrate that the occurrence modes of Ag are complex and diversiform. It might be associated with clay minerals, organic matter, sulfides and also occurred as native silver and sulfides with nanometer in size. Combined with results of previous studies, we suggest that the sulfides, clay minerals and organic matter which hosted in the Ni-Mo-PGE polymetallic ores of black shales can play the roles of important reduction and adsorption geochemical barriers for the enrichment and distribution of silver. This study further implies that the selective chemical dissolution and transmission electron microscopy may pave the way to study the occurrence modes of other noble metals in black shales.  相似文献   

9.
The comparative study of organic matter in carbonate rocks and argillaceous rocks from the same horizon indicates that the organic thermal maturities of carbonate rocks are much lower than those of argillaceous rocks .Ana extensive analysis of extracted and inclused organic matter from the same sample shows that inclused organic matter is different from extracted organic matter,and the thermal maturity of the former is usually lower than that of the latter in terms of biomarker structural parameters.It seems that carbonate mineras could preserve organic matter and retard organic maturation.The inclused organic matter,abundant in most carbonate rocks,will be released from minerals and transformed into oil and gas during the high-thermal maturity stage.  相似文献   

10.
试论天然有机质及其与铀矿化的关系   总被引：1，自引：0，他引：1  
王剑锋 《地球化学》1983,(3):294-302
Uranium is so intimately associated with carbonaceous matter in marine black shales and some sandstone-type uranium deposits that it is said to be “fixed” by organic substances. But different kinds sf organic matter are not of equal importance in the geochemistry of uranium. The nature and origin of organic substances in uranium deposits and the role that they plays in transporting and concentrating uranium are different from place to place. The reason why uranium is associated with certain types of organic matter (for example humus or bitumen) is described in this paper from geochemical viewpoint.  相似文献   

11.
The Mayuan stratabound Pb-Zn deposit in Nanzheng,Shaanxi Province,is located in the northern margin of the Yangtze Plate,in the southern margin of the Beiba Arch.The orebodies are stratiform and hosted in breciated dolostone of the Sinian Dengying Formation.The ore minerals are primarily sphalerite and galena,and the gangue minerals comprise of dolomite,quartz,barite,calcite and solid bitumen.Fluid inclusions from ore-stage quartz and calcite have homogenization tempreatures from 98 to 337℃ and salinities from 7.7 wt%to 22.2 wt%(NaCl equiv.).The vapor phase of the inclusions is mainly composed of CH_4 with minor CO_2 and H_2S.The δD_(fluid) values of fluid inclusions in quartz and calcite display a range from-68‰ to-113‰(SMOW),and the δ~(18)O_(fluid)values calculated from δ~(18)O_(quartz) and δ~(18)O_(calcite) values range from 4.5‰ to 16.7‰(SMOW).These data suggest that the ore-forming fluids may have been derived from evaporitic sea water that had reacted with organic matter.The δ~(13)C_(CH4) values of CH_4 in fluid inclusions range from-37.2‰ to-21.0‰(PDB),suggesting that the CH_4 in the ore-forming fluids was mainly derived from organic matter.This,together with the abundance of solid bitumen in the ores,suggest that organic matter played an important role in mineralization,and that the thermochemical sulfate reduction(TSR) was the main mechanism of sulfide precipitation.The Mayuan Pb-Zn deposit is a carbonate-hosted epigenetic deposit that may be classified as a Mississippi Valley type(MVT) deposit.  相似文献   

12.
The Songliao Basin is one of the most important petroliferous basins in northern China. With a recent gradual decline in conventional oil production in the basin, the exploration and development of unconventional resources are becoming increasingly urgent. The Qingshankou Formation consists of typical Upper Cretaceous continental strata, and represents a promising and practical replacement resource for shale oil in the Songliao Basin. Previous studies have shown that low-mature to mature Qingshankou shale mainly preserves type Ⅰ and type Ⅱ1 organic matter, with relatively high total organic carbon(TOC) content. It is estimated that there is a great potential to explore for shale oil resources in the Qingshankou Formation in this basin. However, not enough systematic research has been conducted on pore characteristics and their main controlling factors in this lacustrine shale reservoir. In this study, 19 Qingshankou shales from two wells drilled in the study area were tested and analyzed for mineral composition, pore distribution and feature evolution using Xray diffraction(XRD), scanning electron microscopy(SEM), low-pressure nitrogen gas adsorption(N2-GA), and thermal simulation experiments. The XRD results show that clay, quartz, and feldspar are the dominant mineral constituents of Qingshankou shale. The clay minerals are mostly illite/smectite mixed layers with a mean content of 83.5%, followed by illite, chlorite, and kaolinite. There are abundant deposits of clay-rich shale in the Qingshankou Formation in the study area, within which many mineral and organic matter pores were observed using SEM. Mineral pores contribute the most to shale porosity;specifically, clay mineral pores and carbonate pores comprise most of the mineral pores in the shale. Among the three types of organic matter pores, type B is more dominant the other two. Pores with diameters greater than 10 nm supply the main pore volume;most are half-open slits and wedge-shaped pores. The total pore volume had no obvious linear relationship with TOC content, but had some degree of positive correlation with the content of quartz + feldspar and clay minerals respectively. However, it was negatively correlated with carbonate mineral content. The specific surface area of the pores is negatively related to TOC content, average pore diameter, and carbonate mineral content. Moreover, it had a somewhat positive correlation with clay mineral content and no clear linear relationship with the content of quartz + feldspar. With increases in maturity, there was also an increase in the number of carbonate mineral dissolution pores and organic matter pores, average pore diameter, and pore volume, whereas there was a decrease in specific surface area of the pores. Generally, the Qingshankou shale is at a low-mature to mature stage with a TOC content of more than 1.0%, and could be as thick as 250 m in the study area. Pores with diameters of more than 10 nm are well-developed in the shale. This research illustrates that there are favorable conditions for shale oil occurrence and enrichment in the Qingshankou shale in the study area.  相似文献   

13.
Two major characters are recognized with respect to the evolution of organic matter during diagenesis of carbonate rocks; (1) expellation of organic matter from carbonate minerals through crystallization, which could reduce the amount of organic matter significantly in the early stage of diagenesis; (2) protection of organic matter by the minerals, especially in the late stage of diagenesis. According to their nature and relations to the protection during diagenesis, three majer forms of disseminated organic matter in carbonate rocks can be distinguished: adsorbed, ctystallization-trapped organic matter and organic inclusions. Owing to the protection by minerals the maturation process of disseminated organic matter proceeds very slowly, and the matority of crystallization-trapped organic matter may play an important role in carbonate source rocks. Most of the organic inclusions are migrated organic matter, such as hydrocarb ons; so organic inclusions may be a good indicator which can be used to study the primary,secondary migration and the concentration of oil and gas in carbonate source rocks and carbonate reservoir strata,  相似文献   

14.
More and more evidence indicates that organic matter (OM) in immature organicrich sediments and sedimentary rocks is chemically adsorbed onto the outer surfaces of minerals and into interlayer (inner) surfaces of smectitic clay minerals in the form of amorphous molecular-scale carbon. But there have been few reports about the occurrence of highly mature OM in marine black shales ( petroleum source rocks ). The occurrence of highly mature OM in the black shales of basal Cambrian from northern Tarim Basin is studied in this paper. Based on the comprehensive analyses of total organic carbon contents (TOC) , maximum thermolysis tempera tures ( Tmax ) of OM, mineral surface areas (MSA) ,and scanning electronic microscopic (SEM) and transmission electronic microscopic (TEM) observations of the black shales, it is concluded that the highly mature OM in the marine black shales of the basal Cambrian from northern Tarim Basin occurs in particulates ranging in size from 1 to 5 μm in diameter. Through the contrast of the occurrence of the highly mature OM in the black shales with that of the immature ones in modern marine continental margin sediments, some scientific problems are proposed, which are worth to study further in detail.  相似文献   

15.
We compared the stable carbon isotopic records from a loess transect of the Jiaochang in the eastern Tibetan Plateau, spanning the last ~21,000 years, with multiproxy data for pedogenesis, including magnetic susceptibility, clay fraction, Fed/Fet ratio, carbonate and total organic carbon content, in order to probe the mechanisms of δ13C values of organic matter and Late Quaternary climate variations in the eastern Tibetan Plateau. Our results indicate that there is no simple relationship between δ13C of organic matter and summer monsoon variations. The change in δ13C values of organic matter (in accordance with the ratios of C3 to C4 plants) results from the interaction among temperature, aridity and atmospheric pCO2 level. Drier climate and lower atmospheric pCO2 level contribute to positive carbon isotopic excursion, while negative carbon isotopic excursion is the result of lower temperature and increased atmospheric pCO2 level. Additionally, our results imply that the Tibetan monsoon may play an important role in climate system in the eastern Tibet Plateau, which specifically reflects frequently changing climate in that area. The results provide new insights into the forcing mechanisms on both the δ13C values of organic matter and the local climate system.  相似文献   

16.
Marine strata are widely exposed in the Hushan and Chaohu areas, Lower Yangtze region. As biomarker geochemistry of the strata has not been well documented, this paper deals with the biomarker composition of representative samples collected from the Silurian, Carboniferous and Triassic systems and their geological implications, thus providing clues to marine organic matter. On the basis of experimental results, it is shown that abundant biomarkers (e.g. n-alkanes, isoprenoids, terpanes and steranes) were detected. As organic matter in the strata is highly to over mature in general based on petrologic microobservation, some biomarkers (mainly n-alkanes) except terpanes and steranes cannot reflect the source, depositional environment and maturity of organic matter. Thus, primarily based on analyses of the terpanes and steranes, it is suggested that organic matter in the Silurian and Carboniferous strata is derived mainly from lower organisms, while higher plants are predominant in the Triassic organic matter. This further indicates that the depositional environment may have transformed from the marine to continental facies in the Late Triassic. These results provide new evidence for the study of regional depositional evolution, and have enriched the study of biological composition of organic matter. In addition, the biomarker geochemistry of organic matter at high to over maturation stage is addressed.  相似文献   

17.
The Jurassic Yanan Formation is one of the most important coal-producing formations and hydrocarbon source rocks in the Ordos Basin, North China. To evaluate the shale gas potential of the Yanan shale, a total of 48 samples from north Ordos Basin were sampled, and their geochemical, petrological, mineralogical and pore characteristics were investigated. It was found that the shale samples are a suite of early mature source rock. The total organic carbon (TOC) content ranges from 0.33% to 24.12% and the hydrogen index (HI) ranges from 43.31mg/g to 330.58 mg/g. The relationship between Tmax and HI indicates the organic matter is type Ⅱ-Ⅲ. This conclusion is also supported by the organic petrological examination results, which shows that the kerogen is mainly liptinite and vitrinite. Minerals in the samples are composed mainly of quartz, clay and feldspar, and the clay minerals are composed of prevailing kaolinite, illite/smectite, chlorite and a small amount of illite. Under scanning electron microscope, OM pores in the Yanan shale are scarce except pores come from the kerogen intrinsic texture or clay aggregates within the organic particles. As the weak compaction caused by shallow burial depth, interparticle pores and intraparticle pores are common, the hydrocarbon storage capacity of the Yanan shale was improved. According to evaluation, the Yanan shale is considered as a good shale gas reservoir, but its hydrocarbon potential is more dependent on biogenic and coal-derived gas as the thermogenic gas is limited by the lower thermal maturity.  相似文献   

18.
As the two important components of shale, organic matter(OM) and clay minerals are usually thought to strongly influence the hydrocarbon generation, enrichment and exploitation. The evolution process of OM and clay minerals as well as their interrelationship over a wide range of thermal maturities are not completely clear. Taking Yanchang(T_3y), Longmaxi(S_1l) and Niutitang(?_1n) shales as examples, we have studied the microstructure characteristics of OM and clay minerals in shales with different thermal maturities. The effects of clay minerals and OM on pores were reinforced through sedimentation experiments. Using a combination of field emission scanning electron microscopy(FESEM) and low-pressure N_2 adsorption, we investigated the microstructure differences among the three shales. The results showed that both OM and clay minerals have strong effects on pores, and small mesopore(2–20 nm) is the dominant pore component for all three samples. However, the differences between the three samples are embodied in the distribution of pore size and the location. For the T_3y shale, clay minerals are loosely arranged and develop large amounts of pores, and fine OM grains often fill in intergranular minerals or fractures. Widespread OM pores distribute irregularly in S_1l shale, and most of the pores are elliptical and nondirectional. The ?_1n shale is characterized by the preferred orientational OM-clay aggregates, and lots of pores in the composites are in the mesopore range, suggesting that over maturity lead to the collapse and compaction of pores under huge pressure of strata. The results of the current research imply that with increasing thermal maturity, OM pores are absent at low maturity(T_3y), are maximized at high maturity(S_1l) and are destroyed or compacted at over-mature stage(?_1n). Meanwhile, clay minerals have gone through mineral transformation and orientational evolution. The interaction of the two processes makes a significant difference to the microstructure evolution of OM and clay minerals in shale, and the findings provide scientific foundation in better understanding diagenetic evolution and hydrocarbon generation of shale.  相似文献   

19.
Based on gas chromatography and gas chromatography mass spectrometry techniques, the authors examined biomarker characteristics of the Ganquan Formation source rocks in the area of Dahulishan, Ejina, and analyzed the information and petroleum geological significance that were indicated by the source of organic matter, sedimentary environment and maturity and so on. Gas chromatography peak of saturated hydrocarbons from the Ganquan Formation source rocks showed "the former peak" of the single peak distribution, the main peak of carbon being C18 , indicating the main sources of organic matter with marine organic matter. Pr/Ph ranges from 0.3 to 0.6, indicating a strongly reducing sedimentary environment. Biomarker assemblages of the Ganquan Formation source rocks are abundant in tricyclic terpane with long side chains, with a high level of gammacerane, showing dominant distribution of C27 sterane. High contents of gammacerane in organic matter show organic facies of source rocks in the saltwater sedimentary environment. That average hopane/sterane ratio is 0.59, showing that algae have made more contributions to organic matter than bacteria. And the high level of C27 steranes shows that algae are the main source of hydrocarbon precursors. The Ganquan Formation’s methylphenanthrene index, which is an effective molecular parameter index to measure thermal evolution of organic matter, ranges from 0.35 to 0.50, and the conversion of vitrinite reflectance Rc from it is within the range of 2.00-2.09, indicating that the Ganquan Formation source rocks are in the over-mature stage of thermal evolution.  相似文献   

20.
The exploration conducted in the Bohai Bay basin, eastern China has demonstrated that the abundant petroleum resources have close affinities to the hydrocarbon kitchen with rich organic matter. A number of oil-generating associations with various characteristics of organic geochemistry and assemblages of multiple reservoir facies are developed due to the multi-center sedimentation, multi-source supply and multi-cycle evolution of filling, which have resulted in the formation of multiple oil and gas accumulation zones of various layers and trap styles. Among them the Paleogene Shahejie Formation is the most important hydrocarbon accumulation combination in the Dongying sag. Heretofore, its proved reserve has reached nearly 1.8×109t, which accounts for more than 90% of the total proved reserves of the Dongying sag. Based on previous studies, more than 600 source rock samples and 186 crude oil samples of the Shahejie Formation, collected from 30 oilfields, have been treated with organic geochemical testing  相似文献   

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