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1.
An infrared routine has been developed to estimate the aliphatic portion of kerogen carbon in sedimentary rocks. The procedure does not require isolation of the organic matter and is based on a computer-assisted determination of global band areas in the region of the aliphatic carbon-hydrogen stretching vibrations around 2900cm−1. From these integrated absorptions the amount of aliphatic carbon Cal (mg of aliphatic carbon per gram of solvent-extracted rock) is calculated by means of a calibration with model rocks. Carbonate overtones which interfere in the case of limestones are eliminated by comparison to a CaCO3 standard.The method has been applied to rocks containing kerogens of different types and maturities at TOC levels of 0.5 to 12%. The aliphatic carbon concentrations range from 0.5 to 60mg·g−1 and correlate reasonably well with the residual genetic potentials of the rocks as measured by S2 values from Rock-Eval pyrolysis. The ratio S2/Cal is found to decrease with burial depth reflecting a maturity enhanced conversion of aliphatic carbon to fixed aromatic carbon under Rock-Eval conditions.  相似文献   

2.
A 13-step alkaline permanganate degradation of Bulgarian oil shale kerogen concentrate at ambient temperature was carried out. A high yield of oxidation products (90.1%) and a low yield of gaseous products (2.79%) were obtained. IR and 1H NMR spectroscopic studies have shown that two significantly different types of high molecular products are present in kerogen. Further oxidation of these structures leads to the formation of low molecular aliphatic and aromatic acids, proven by gas chromotography (GC) and gas chromatography-mass spectrometry (GC-MS). The data obtained at these mild conditions allow us to acquire detailed information about the aromatic structures and polymethylene chain lengths in kerogen.The 5-step oxidation of the kerogen at 90 °C provides information about stable aromatic structures. Soluble and insoluble polyfunctional acids in acid medium have close molecular masses and spectral characteristics. The amount of benzene and naphthalene carboxylic acids is 11.3% of the organic matter of the oil shale.  相似文献   

3.
The crystal structure of ludwigite from Vranovac ore deposit (Boranja Mt., Serbia) was refined using the X-ray powder diffraction (XRPD) Rietveld method in the space group Pbam to a final RB=7.45% and RF=5.26%. It has the unit cell dimensions of: a=9.2515(2) ?; b=12.3109(2) ?; c=3.03712(7) ?; and V=345.91(1) ?3. The calculated distances and angles are mostly in good agreement with the Mg2+-Fe2+ substitutions across the M(1) and M(3) sites, as well as with the Fe3+-Al3+ replacement in the M(4) site. However, the mean observed M(2)-O distance is considerably shorter than prescribed, due to a slight increase of the Fe3+ content in the M(2) site. Such replacement was compensated by slight increase of the Fe2+ content in the M(4) site, resulting in the (Mg1.48Fe2+0.46Fe3+0.05Mn0.02)2.01(Fe3+0.94Fe2+0.04Al0.02)1.00B1.00O5 composition. The formation temperature was estimated to be about 500–600°C. The influences of the various chemical compositions to the crystallographic parameters, M-O distances, M(3) and M(4) sites shift, distortion parameters and estimated valences, were also studied and compared with other reference samples.  相似文献   

4.
This work presents geochemical characterization of isolated kerogen out of clay fraction using petrography studies, infrared absorption and solid state 13C nuclear magnetic resonance (NMR) spectroscopy, with N‐alkane distributions of saturated hydrocarbon. Mineralogical study of clay mineral associations was carried out using X‐ray diffraction (XRD), on Ypresian phosphatic series from Gafsa‐Metlaoui basin, Tunisia. The XRD data indicate that smectite, palygorskite and sepiolite are the prevalent clay minerals in the selected samples. In this clay mineral association, the N‐alkane (m/z = 57) distribution indicates that the marine organic matter is plankton and bacterial in origin. The kerogens observed on transmitted light microscopy, however, appear to be totally amorphous organic matter, without any appearance of biological form. The orange gel‐like amorphous organic matter with distinct edges and homogenous texture is consistent with a high degree of aliphaticity. This material has relatively intense CH2 and CH3 infrared bands in 13C NMR peaks. This aliphatic character is related to bacterial origin. Brown amorphous organic matter with diffuse edges has a lower aliphatic character than the previous kerogen, deduced from relatively low CH2 and CH3 infrared and 13C NMR band intensities.  相似文献   

5.
1 Introduction Chevkinite groups can be assigned to the chevkinite-(Ce) subgroup and perrierite-(Ce) subgroup in accord with the angle β : β ≈ 100o for the chevkinite subgroup and β ≈ 113o for the perrierite subgroup. Chevkinite-(Ce), polykovite-(Ce) and Maoniupingite (new mineral No. 017 of 2003) belong to the former subgroup, while renjeite and matsubaraite belong to the latter group. As strontio-chevkinite is a Sr-analogue of perrierite, usually the natural chevkinite-(Ce) group min…  相似文献   

6.
《China Geology》2020,3(4):545-557
The composition of gas released under vacuum by crushing from the gas shale of Longmaxi Formation in Upper Yangtze Plate, Southern China was systematically investigated in this study. The effect of residual gas release on pore structures was checked using low-pressure nitrogen adsorption techniques. The influence of particle size on the determination of pore structure characteristics was considered. Using the Frenkel-Halsey-Hill method from low-pressure nitrogen adsorption data, the fractal dimensions were identified at relative pressures of 0−0.5 and 0.5−1 as D1 and D2, respectively, and the evolution of fractal features related to gas release was also discussed. The results showed that a variety component of residual gas was released from all shale samples, containing hydrocarbon gas of CH4 (29.58% −92.53%), C2H6 (0.97% −2.89%), C3H8 (0.01% −0.65%), and also some non-hydrocarbon gas such as CO2 (3.54% − 67.09%) and N2 (1.88%−8.07%). The total yield of residual gas was in a range from 6.1 μL/g to 17.0 μL/g related to rock weight. The geochemical and mineralogical analysis suggested that the residual gas yield was positively correlated with quartz (R2=0.5480) content. The residual gas released shale sample has a higher surface area of 17.20−25.03 m2/g and the nitrogen adsorption capacity in a range of 27.32−40.86 ml/g that is relatively higher than the original samples (with 9.22−16.30 m2/g and 10.84−17.55 ml/g). Clearer hysteresis loop was observed for the original shale sample in nitrogen adsorption-desorption isotherms than residual gas released sample. Pore structure analysis showed that the proportions of micro-, meso- and macropores were changed as micropores decreased while meso- and macropores increased. The fractal dimensions D1 were in range from 2.5466 to 2.6117 and D2 from 2.6998 to 2.7119 for the residual gas released shale, which is smaller than the original shale. This factor may indicate that the pore in residual gas released shale was more homogeneous than the original shale. The results indicated that both residual gas and their pore space have few contributions to shale gas production and effective reservoir evaluation. The larger fragments samples of granular rather than powdery smaller than 60 mesh fraction of shale seem to be better for performing effective pore structure analysis to the Longmaxi shale.  相似文献   

7.
Six oil shales and their kerogen concentrates have been studied using 13C CP/MAS NMR techniques to study the distribution of organic carbon species. It is found that if the aromatic and aliphatic regions are divided at about 80 or 100 ppm, the apparent aromaticities of a raw shale and its kerogen concentrate are in good agreement. The presence of oxygen-substituted carbons in the raw shales and their depletion in the kerogen concentrates are observed and discussed.  相似文献   

8.
Six oil shales and their kerogen concentrates have been studied using 13C CP/MAS NMR techniques to study the distribution of organic carbon species. It is found that if the aromatic and aliphatic regions are divided at about 80 or 100 ppm, the apparent aromaticities of a raw shale and its kerogen concentrate are in good agreement. The presence of oxygen-substituted carbons in the raw shales and their depletion in the kerogen concentrates are observed and discussed.  相似文献   

9.
The paper presents data on the composition of biomarkers from bitumen extracts and the chemical structure of kerogen from Corg-rich sedimentary rocks before and after hydrothermal treatment in an autoclave at 300°C. Samples selected for this study are kukersite and Ordovician Dictyonema shale from the Baltics, Domanik oil shale from the Ukhta region, Upper Permian brown coal from the Pre-Ural foredeep, carbonaceous shale from the Oxfordian horizon of the Russian plate, and Upper Jurassic oil shales from the Sysola oil shale bearing region. The rocks contain type I, II, III, and II-S kerogens. The highest yield of extractable bitumen is achieved for Type II-S kerogen, whereas Type III kerogen produces the lowest amount of bitumen. The stages of organic matter thermal maturation achieved during the experiments correspond to a transition from PC2–3 to MC1–2. The 13C NMR data on kerogen indicate that the aromatic structures of geopolymers underwent significant changes.  相似文献   

10.
Five of the most important Colombian coals were studied using Photoacoustic Fourier transform infrared (PA-FTIR) spectroscopy. The PA-FTIR spectra were used to obtain structural parameters and to determine the analytical potential of this technique. The molecular structural parameters, CH2/CH3, fa, Hal/Har, and (R/C)u were correlated with fixed carbon contained in the samples to determine aliphatic hydrogen, Hal, and the aromatic hydrogen, Har in coals studied here. These parameters enabled the determination of aromaticity, fa, which was found to be between 0.66 and 0.98. The aliphatic and aromatic regions were considered between 3005–2760 cm?1 and 912–670 cm?1, respectively. Finally, using the molecular structural parameters, the grade of maturation (rank) of coal samples studied was determined.  相似文献   

11.
Potassium permanganate oxidative degradations were conducted for kerogens isolated from Cretaceous black shales (DSDP Leg 41, Site 368), thermally altered during the Miocene by diabase intrusions and from unaltered samples heated under laboratory conditions (250–500°C).Degradation products of less altered kerogens are dominated by normal C4–C15 α,ω-dicarboxylic acids, with lesser amounts of n-C16 and n-C18 monocarboxylic acids, and benzene mono-to-tetracarboxylic acids. On the other hand, thermally altered kerogens show benzene di-to-tetracarboxylic acids as dominant degradation products, with lesser or no amounts (variable depending on the degree of thermal alteration) of α,ω-dicarboxylic acids. Essentially no differences between the oxidative degradation products of naturally- and artificially-altered kerogens are observed.As a result of this study, five indices of aromatization (total aromatic acids/kerogen; apparent aromaticity; benzenetetracarboxylic acids/total aromatic acids; benzene-1,2-dicarboxylic acid/benzenedicarboxylic acids; benzene-1,2,3-tricarboxylic acid/benzenetricarboxylic acids) and two indices of aliphatic character (Total aliphatic acids/kerogen; Aliphaticity) are proposed to characterize the degree of thermal alteration of kerogens.Furthermore, a good correlation is observed between apparent aromaticity estimated by the present KMnO4 oxidation method and that from the 13C NMR method (DENNIS et al., 1982).  相似文献   

12.
We describe the new mineral species titanium,ideally Ti,found in the podiform chromitites of the Luobusha ophiolite in Tibet,People’s Republic of China.The irregular crystals range from 0.1 to 0.6 mm in diameter and form an intergrowth with coesite and kyanite.Titanium is silver grey in colour,the luster is metallic,it is opaque,the streak is grayish black,and it is non-fluorescent.The mineral is malleable,has a rough to hackly fracture and has no apparent cleavage.The estimated Mohs hardness is 4,and the calculated density is 4.503 g/cm3.The composition is Ti 99.23-100.00 wt%.The mineral is hexagonal,space group P63 /mmc.Unit-cell parameters are a 2.950(2),c 4.686(1),V 35.32(5) 3,Z = 2.The five strongest powder diffraction lines [d in(hkl)(I/I0)] are: 2.569(010)(32),2.254(011)(100),1.730(012)(16),1.478(110)(21),and 0.9464(121)(8).The species and name were approved by the CNMNC(IMA 2010–044).  相似文献   

13.
Lisiguangite, CuPtBiS3, is a new mineral species discovered in a PEG-bearing, Co-Cu sulfide vein in garnet pyroxenite of the Yanshan Mountains, Chengde Prefecture, Hebei Province, China. It is associated with chalcopyrite and bornite, galena, minor pyrite, carrolite, molybdenite and the platinum-group minerals daomanite (CuPtAsS2), Co-bearing malanite (Cu(Pt, Co)2S4) sperrylite, moncheite, cooperite and malyshevite (CuPdBiS3), rare damiaoite (Pt2In3) and yixunite (Pt3In). Lisiguangite occurs as idiomorphic crystals, tabular or lamellae (010) and elongated [100] or as aggregates, up to 2 mm long and 0.5 mm wide. The mineral is opaque, has lead-gray color, black streak and metallic luster. The mineral is non-fluorescent. The observed morphology displays the following forms: pinacoids {100}, {010}, {001}, and prism {110}. No twining is observed. The a:b:c ratio, calculated from unit-cell parameters, is 0.6010:1:0.3836. Cleavage: {010} perfect, {001} distinct, {100} may be visible. H Mohs: 21/2; VHN25=46.7-49.8 (mean 48.3) kg/mm2. Tenacity: brittle. Lisiguangite is bright white with a yellowish tint. In reflected light it shows neither internal reflections nor bireflectance or pleochroism. It has weak to moderate anisotropy (blue-greenish to brownish) and parallel-axial extinction. The reflectance values in air (and in oil) for R3, R4 and (imR3, imR4), at the standard Commission on Ore Mineralogy wavelengths are: 37.5, 35.7 (23.4, 22.3) at 470 nm; 38.6, 36.5 (23.6, 22.6) at 546 nm; 39.4, 37.5 (23.6, 22.7) at 589 nm and 40.3, 38.2 (23.7, 22.9) at 650 nm. The average of eight electron-microprobe analyses: Cu 12.98, Pt 30.04, Pd 2.69, Bi 37.65 and S 17.55, totaling 100.91%, corresponding to Cu1.10(Pt 0.83, Pd0.14)Σ0.97Bi0.97S2.96 based on six atoms apfu. The ideal formula is CuPtBiS3. The mineral is orthorhombic. Space group: P212121, a=7.7152(15)?,b=12.838(3)?, c=4.9248(10)?, V=487.80(17)?3, Z=4. The six strongest lines in the X-ray powder-diffraction pattern [d in ? (I) (h k l) are 6.40(30)(020), 3.24(80)(031), 3.03(100)(201), 2.27(40)(051), 2.14(50)(250), 1.865(60)(232).  相似文献   

14.
The main geological factors controlling the accumulation and yield of marine-facies shale gas reservoirs are the focus of the current shale gas exploration and development research. In this study, the Wufeng-Longmaxi Formation in the Dingshan area of southeast Sichuan was investigated. Shale cores underwent laboratory testing, which included the evaluation of total organic carbon(TOC), vitrinite reflectance(Ro), whole-rock X-ray diffraction(XRD), pore permeability,and imaging through field emission scanning electron microscopy(FE-SEM). Based on the results of natural gamma ray spectrum logging, conventional logging, imaging logging, and seismic coherence properties, the exploration and development potential of shale gas in the Dingshan area have been discussed comprehensively. The results showed that(1)layer No. 4(WF2-LM4) of the Wufeng-Longmaxi Formation has a Th/U ratio 2 and a Th/K ratio of 3.5–12. Graptolites and pyrite are relatively abundant in the shale core, indicating sub-high-energy and low-energy marine-facies anoxic reducing environments.(2) The organic matter is mainly I-type kerogen with a small amount of II1-type kerogen. There is a good correlation among TOC, Ro, gas content, and brittle minerals; the fracturing property(brittleness) is 57.3%. Organic and inorganic pores are moderately developed. A higher pressure coefficient is correlated with the increase in porosity and the decrease in permeability.(3) The DY1 well of the shale gas reservoir was affected by natural defects and important latestage double destructive effects, and it is poorly preserved. The DY2 well is located far from the Qiyueshan Fault. Large faults are absent, and upward fractures in the Longmaxi Formation are poorly developed. The well is affected by low tectonic deformation intensity, and it is well preserved.(4) The Dingshan area is located at the junction of the two sedimentary centers of Jiaoshiba and Changning. The thickness of the high-quality shale interval(WF2-LM4) is relatively small, which may be an important reason for the unstable production of shale gas thus far. Based on the systematic analysis of the geological factors controlling high-yield shale gas enrichment in the Dingshan area, and the comparative analysis with the surrounding typical exploration areas, the geological understanding of marine shale gas enrichment in southern China has been improved. Therefore, this study can provide a useful reference for shale gas exploration and further development.  相似文献   

15.
A new superstructure was found in bafertisite [(Ba0.98Na0.02)1.00(Fe1.71Mn0.26Mg0.01)1.98 TiO[(Si1.82Ti0.04Al0.03Cr0.01)1.90O7](OH1.40F0.53Cl0.03)1.96] from Donghai County, Jiangsu Province, China. The occurrence of the superstructure reflections were observed by single crystal diffraction using a SMAR APEX CCD. The a*, b*and c* axis directions revealed extra weak reflection spots of the superstructure. The apparent 2a, 2b and 2c superstructure is monoclinic with unit cell a＝10.6502(15)?, b＝13.7233(19)?, c＝21.6897(3)?, α＝90o, β＝94.698(3)o, γ＝90o,space group Cm,Z=16. If c* extra weak reflections are ignored, the secondary supercell gave a cell a＝10.6548(15)?, b＝13.7284(19)?, c＝11.6900(17)?, α＝90o, β＝112.322(28)o, γ＝90o,space group Cm,Z=8. The basic subcell was obtained by ignoring all extra weak reflection spots and gave: a＝5.3249(17)?, b＝6.8669(22)?, c＝10.8709(36)?, α＝90o, β＝94.740(62)o, γ＝90o,space P21/m,Z=2. The superstructure has been refined to R = 0.063 for 7805 [R(int) = 0.0266] unique reflections I>2δ(I). The structure consists of an octahedra (O) sheet sandwiched between two heteropolyhedral (H) sheets. These sheets consist of Ti–octahedra and twin tetrahedral disilicate groups [Si2O7]. The O sheet comprises (Fe,Mg)O4 octahedra. The large Ba cation is located in the interlayer area. The refined structure shows Fe, Mg are partly ordered. The shifting of the TiO6 octahedron and SiO4 tetrahedron sites in the sheet may be a consequence of the superstructure.  相似文献   

16.
The kerogen of a sample of Estonian Kukersite (Ordovician) was examined by spectroscopic (solid state 13C NMR, FTIR) and pyrolytic (“off-line”, flash) methods. This revealed an important contribution of long, linear alkyl chains in Kukersite kerogen. The hydrocarbons formed upon pyrolysis are dominated by n-alkanes and n-alk-1-enes and probably reflect a major contribution of selectivity preserved, highly aliphatic, resistant biomacromolecules from the outer cell walls of Gloeocapsomorpha prisca. This is consistent with the abundant presence of this fossilized organism in Kukersite kerogen. In addition high amounts of phenolic compounds were identified in the pyrolysates. Series of non-methylated, mono-, di- and trimethylated 3-n-alkylphenols, 5-n-alkyl-1,3-benzenediols and n-alkylhydroxybenzofurans were identified. All series of phenolic compounds contain long (up to C19), linear alkyl side-chains. Kukersite kerogen is, therefore, an aliphatic type II/I kerogen, despite the abundance of free phenolic moieties. This study shows that phenol-derived moieties are not necessarily associated with higher plant-derived organic matter.The flash pyrolysate of Kukersite kerogen was also compared with that of the kerogen of the Guttenberg Oil Rock (Ordovician) which is also composed of accumulations of fossilized G. prisca. Similarities in the distributions of hydrocarbons and sulphur compounds were noted, especially for the C1–C6 alkylbenzene and alkylthiophene distributions. However, no phenolic compounds were detected in the flash pyrolysate of the Guttenberg kerogen. Possible explanations for the observed similarities and differences are discussed.  相似文献   

17.
A new mineral species, named naquite(FeSi), is found in the podiform chromitites of the Luobusha ophiolite in Qusong County, Tibet, China. The detailed composition is Fe 65.65, Si 32.57 and Al 1.78 wt%. The mineral is cubic, space group P213. The irregular crystals range from 15 to 50 μm in diameter and form an intergrowth with luobusaite. Naquite is steel grey in color, opaque, with a metallic lustre and gives a grayish-black streak. The mineral is brittle, has a conchoidal fracture and no apparent cleavage. The estimated Mohs hardness is 6.5, and the calculated density is 6.128 g/cm3. Unit-cell parameters are a 4.486 (4) ?, V 90.28 (6) ?3, Z=4. The five strongest powder diffraction lines [d in ? (hkl) (I/I0)] are: 3.1742 (110) (40), 2.5917(111) (43), 2.0076 (210) (100), 1.8307 (211) (65), and 1.1990 (321) (36). Originally called ‘fersilicite’, the species and new name have now been approved by the CNMNC (IMA 2010–010).  相似文献   

18.
A maturity indexing procedure based on the isotopic difference between the total accumulated methane produced by exhaustive pyrolysis and the kerogen (Δ13C) and the mole ratio of methane to kerogen carbon (CMR), has been tested by applying a standardized technique, i.e. exhaustive pyrolysis (600°C for 120 hr) of extracted-powdered samples and measurement of the amounts and isotopic composition of the methane and kerogen carbon, on a suite of 15 Bakken shale samples.A linear relation was found between the carbon mole ratio of pyrolysis-derived methane and total organic carbon and the δ13C difference between the pyrolysis-derived methane and total organic carbon (r = −0.79); and between the amount of CH4 generated from exhaustive pyrolysis and H/C atomic ratios (r = +0.91).  相似文献   

19.
Compound-specific stable carbon isotope (δ ) measurements on the aliphatic hydrocarbons released from an immature Tertiary oil shale (Göynük, Turkey) via hydropyrolysis, following solvent extraction and a milder hydrogenation treatment, have further highlighted that significant compositional differences may exist between the principal aliphatic constituents of the solvent extractable (bitumen) phase and the insoluble macromolecular network (kerogen) comprising the bulk of sedimentary organic matter. Whilst inputs from diverse sources; including algae, bacteria and terrestrial higher plants, were implied from analysis of solvent-extractable alkanes, the much larger quantities of kerogen-bound n-alkyl constituents released by hydropyrolysis had a uniform isotopic signature which could be assigned to (freshwater) algae. Remarkably, the aliphatics bound to the kerogen by relatively weak covalent bonds, liberated via catalytic hydrogenation, appeared to comprise mainly allochthonous higher plant-derived n-alkanes. These results provide further compelling evidence that the molecular constituents of bitumen and, indeed, of low-yield kerogen degradation products, are not necessarily reliable indicators of kerogen biogenicity, particularly for immature Type I source rocks. The isotopic uniformity of aliphatic n-hydrocarbons released by the high-conversion hydropyrolysis step for the ultralaminae-rich Göynük oil shale, lends further support to the theory that selective preservation of highly resistant aliphatic biomacromolecules is an important mechanism in kerogen formation, at least for alginite.  相似文献   

20.
A 33 step alkaline permanganate degradation of the kerogen from Moroccan Timahdit oil shale (M-Zone) was carried out. A very high total yield of oxidation products was obtained (95.4% based on original kerogen). Detailed GC-MS analyses of ether-soluble acids, acids isolated from aqueous solutions and soluble products of further controlled permanganate dedradation of precipitated, ether-insoluble acids, served as a basis for the quantitative estimation of the participation of various types of products and for comparison with other kerogens. The most interesting finding was the observed uniquely high yield of aromatic oxidation products from an intermediate type I–II kerogen. Taking into account the almost equally dominant aliphatic (50.2%) and aromatic (43.2%) nature of the acidic oxidation products, the existence of an aliphatic cross-linked nucleus mixed with cross-linked aromatic units in the Timahdit shale kerogen is postulated. Uniform distribution of oxidation products throughout the degradation suggested a similar reactivity of the various kerogen constituents towards alkaline permanganate.  相似文献   

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