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Using photometric and image analysis methods, a reasonable technique and procedure have been developed for the determination of maceral group composition and the reflectance of vitrinite. This procedure is introduced by an optimum method for seeking the interval values of each maceral group, i.e., from the “fingerprint” reflectance histogram, it seeks reasonable interval values and distribution values for vitrinite and other maceral groups. After checking and correction, these values can be put into a program and computerized. This method had advantages such as increased speed of analysis and reproducibility of the results. 相似文献
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Since the mid-1980s, Texaco has used the transmittance color index (TCI) of amorphous kerogen as an indicator of kerogen thermal maturation. The technique simply involves the direct measurement of a white-light spectrum as it is transmitted through a particle of amorphous organic matter (AOM). In brief, TCI values are obtained by the analysis of white light originating from a 100-W 6-V tungsten lamp attached to a photometric microscope. The assignment of particular TCI values is based on the increasing curvature of spectra with increasing maturity. TCI curves shift from an average wavelength around 580 nm for samples of immature, amorphous kerogen (i.e., material with a mean, random vitrinite reflectance of about 0.20%) to about 660 nm for samples containing very dark brown to some black particulate material (i.e., kerogen with a mean, random vitrinite reflectance of about 2.15%). The range of TCI values covers all zones of petroleum generation and preservation. In our opinion, TCI can provide as accurate a basis for maturation interpretations as is available from vitrinite reflectance (or from the mean random reflectance of some zooclasts, such as graptolites and chitinozoans), or the widely used visual estimate the thermal alteration index (TAI) or the similarly determined conodont color index (CAI). TCI is probably most useful, however, in those situations where the rocks to be examined have not yet reached the semianthricite coalification stage (≈2.0% vitrinite reflectance). 相似文献
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根据实测的压力和镜质组反射率数据讨论了沉积盆地中镜质组反射率异常的物理化学环境.认为异常压力并不是导致镜质组反射率受到抑制的唯一原因;沉积盆地中有机质镜质组反射率异常的原因除与有机质本身的性质有关外,还与其所处的温度、压力等物理环境及其周围的流体性质、无机元素(矿物)的组成等化学因素密切相关.通过对钻井异常高压带和正常压力带剖面密集取样进行的微量元素与镜质组反射率分析表明,偏酸性、低盐度的流体介质有利于有机质镜质组反射率的增加;通过分析泥岩中的某些元素丰度与镜质组反射率的对应关系,初步确定钙、锰、锶、硼、钡、磷等元素对镜质组反射率的演化有抑制作用,而铁、钴、锌、镍、铷等元素对有机质的热演化具有催化作用.本研究对于有机质成熟校正、油气资源评价和利用成熟度古温标恢复盆地热历史都具有意义. 相似文献
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镜质体反射率的演化并不是人们传统意义上认为的随着温度（深度）的增加成指数增加,而是分阶段演化的。通过对有机质热模拟实验数据和自然演化数据进行分析后发现镜质体反射率的演化可以分为明显的3段：1）缓慢变化阶段,随着温度的增加镜质体反射率缓慢地变化,2）中等快速阶段,随着温度的增加镜质体反射率相比较前一阶段增加速率有明显的加大,3）快速增加阶段,随着温度的增加镜质体反射率呈指数快速增加。这种分阶段的演化是由镜质体本身的化学组成和化学结构所决定的。镜质体反射率演化阶段的划分对于热历史的恢复以及认识镜质体的热演化机制和规律具有重要的意义。 相似文献
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This paper describes an approach for verifying thermal maturity data in a large historical dataset from the Canadian Arctic Islands. A compilation of more than 6000 maturity measurements (vitrinite reflectance and Rock-Eval Tmax) collected over the span of three decades involved a rigorous assessment of data quality. Some common anomalies in interpreting thermal maturity dataset include: (i) elevated thermal maturity due to Cretaceous igneous intrusion in the region, (ii) reworking of refractory material from older rocks into younger strata during the Triassic period, (iii) suppression of vitrinite reflectance and Tmax in hydrogen-rich samples, (iv) low maturity values due to cross-contamination by the younger sediments during drilling process (caving), and (v) offset maturity values obtained from different maturity measurements. The study discusses various independent checks to verify the obtained maturity parameters. The comparison between thermal maturity data with the sonic velocity of shale resulted in a satisfactory correlation. While such a correlation may vary in different sedimentary basins, it produces a useful independent assessment of thermal maturity. The results indicate that increased heat flow during the Jurassic–Early Cretaceous rifting of the Canada Basin may have caused the elevated maturity beyond the expected burial level as suggested by the discrepancy between thermal maturity and sonic velocity data. Given the fact that vitrinite reflectance records only the maximum temperature to which the enclosing rocks were exposed, deviation of the collected reflectance values from the current depth of burial serves as an indicator for the amount of geological uplift. 相似文献
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Ten samples from the Upper Jurassic Naokelekan and Barsarin Formations in an outcrop section near Sargelu Village were studied to evaluate their thermal maturity using vitrinite reflectance method. The studied beds appeared to be mature and within the oil generation window (0.79–1.25 % vitrinite reflectance in immersion oil (Ro)). Some of the reflectance histograms showed bimodal distribution indicating existence of nonindigenous populations which were all ignored during the measurements of the mean value of Ro. Comparison between the results obtained from vitrinite reflectance method and some other methods like pyrolysis and gas chromatography showed variations which finally more reality believed to be for the vitrinite reflectance method. 相似文献
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A.G. Borrego C.V. Araujo A. Balke B. Cardott A.C. Cook P. David D. Flores M. Hmor-Vid W. Hiltmann W. Kalkreuth J. Koch C.J. Kommeren J. Kus B. Ligouis M. Marques J.G. Mendona Filho M. Misz L. Oliveira W. Pickel K. Reimer P. Ranasinghe I. Surez-Ruiz A. Vieth 《International Journal of Coal Geology》2006,68(3-4):151-170
The development of a qualifying system for reflectance analysis has been the scope of a working group within the International Committee for Coal and Organic Petrology (ICCP) since 1999, when J. Koch presented a system to qualify vitrinite particles according to their size, proximity to bright components and homogeneity of the surface. After some years of work aimed at improving the classification system using photomicrographs, it was decided to run a round robin exercise on microscopy samples. The classification system tested consists of three qualifiers ranging from excellent to low quality vitrinites with an additional option for unsuitable vitrinites. This paper reports on the results obtained by 22 analysts who were asked to measure random reflectance readings on vitrinite particles assigning to each reading a qualifier. Four samples containing different organic matter types and a variety of vitrinite occurrences have been analysed. Results indicated that the reflectance of particles classified as excellent, good or poor compared to the total average reflectance did not show trends to be systematically lower or higher for the four samples analysed. The differences in reflectance between the qualifiers for any given sample were lower than the scatter of vitrinite reflectance among participants. Overall, satisfactory results were obtained in determining the reflectance of vitrinite in the four samples analysed. This was so for samples having abundant and easy to identify vitrinites (higher plant-derived organic matter) as well as for samples with scarce and difficult to identify particles (samples with dominant marine-derived organic matter). The highest discrepancies were found for the organic-rich oil shales where the selection of the vitrinite population to measure proved to be particularly difficult. Special instructions should be provided for the analysis of this sort of samples. The certainty of identification of the vitrinite associated with the vitrinite reflectance values reported has been assessed through a reliability index which takes into account the number of readings and the coefficient of variation. The same statistical approach as that followed in the ICCP vitrinite reflectance accreditation program for single seam coals has been used for data evaluation. The results indicated low to medium dispersion for 17 out of 22 participants. This, combined with data from other sets of comparative analyses over a long period, is considered an encouraging result for the establishment of an accreditation program on vitrinite reflectance measurements in dispersed organic matter. 相似文献
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镜质体是一种由高等植物木质素经过生物化学降解作用和凝胶化作用形成的胶状体,在煤和炭质泥页岩中含量高,仅出现在志留纪及其以后的地层中。此外,还有一种海相镜质体,主要由海洋低等生物(藻类、菌类及某些海洋低等动物)经腐殖化作用而形成,主要存在于早古生代及晚古生代页岩和碳酸盐岩地层中。研究表明,海相镜质体反射率(R~o_m)可作为成熟度指标加以应用。海相镜质体成熟作用轨迹不同于镜质体,二者存在一定的相关关系,使用时需把海相镜质体反射率换算为镜质体反射率(R_o)。镜质体反射率是一个寻找隐伏岩体的好方法,作者采用镜质体反射率方法对铜陵地区开展了研究,初步结果表明,铜陵地区全部数值均超过地热增温率理论曲线,说明铜陵地区深部可能有较大的隐伏岩体,深度大约在4~5 km左右。此外,在ZK113号钻孔深度200~260 m处R_o很高(2%~3%),可能预示钻孔旁侧有规模较小的隐伏侵入体,推测距钻孔距离不超过100 m,但具体方位不详。上述研究表明采用镜质体反射率方法寻找隐伏岩体是可行的,它的最大优点是解释的唯一性,R_o数值仅与温度有关,不受其他因素的干扰。 相似文献
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Due to the contrast in thermal conductivity between salt and typical sedimentary formations the presence of salt in various shapes in the sub-surface can have a significant impact on the sub-surface temperature distribution and thermal maturation of source rocks. Using a thermal indicator tomography 1-D modelling system, which deals with salt insertion, the thermal and excess maturity anomalies caused solely by the presence of a salt layer are investigated. Two cases, salt ‘plug’ and ‘lens’, illuminate the different patterns of vitrinite reflectance variation with depth that would be recorded by borehole sampling. Salt can be inserted either as a primary depositional layer or by secondary intrusion at depth. The effects of salt are more dominant on the subsalt layers because: 1 salt insertion changes the burial paths of subsalt sediments. Thus the compaction-driven fluid flow of subsalt sediments, and also basement subsidence, are altered; 2 iso-temperature lines are modified by the presence of the salt and the variation depends on the thickness of the salt layer. The model was also designed to estimate the time of salt insertion and the variation of salt thickness in an inverse sense using present day data on temperature with depth and measured thermal indicators. An investigation is given of the degree to which inverse procedures resolve parameters associated with salt insertion. The sensitivity of those parameters is also discussed. 相似文献
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Roger Sassen 《Organic Geochemistry》1984,5(4):183-186
Study of fossil wood samples with varying contents of uranium suggests that radiation exposure over geologic time results in alteration of vitrinite. The alteration is shown by increased reflectance of vitrinite, increased values of Thermal Alteration Index, decreased atomic H/C ratios, and by loss of fluorescence. Each of these parameters is used to estimate the thermal maturity of kerogen. Unless recognized during interpretation of analytical results, radiation damage of vitrinite results in over-estimation of thermal maturity. 相似文献
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Czechoslovak bituminous coals rich in inertinite contain a considerable amount of inertinite with a reflectance range displaced towards and partly overlapping that of the vitrinite reflectance. Together with the existence of the transitional maceral group of semivitrinite, this causes difficulties in maceral analysis as well as in the technological evaluation of these coals. The relationship between the volatile matter of vitrinite and its reflectance is very close for both vitrinite- and inertinite-rich coals. The analogous relationship between the vitrinite reflectance and the volatile matter of inertinite displays a considerable scatter due to the effects of some higher values of the volatile matter of inertinite — related to the presence of inertinite with relatively low reflectance. The results of investigations into the coking properties of coals rich in inertinite, however, do not supply any proof of a higher fusibility of these coals. 相似文献
14.
Based on the tested data of pressure and vitrinite reflectance of some wells in sedimentary basins, abnormal high pressure
is regarded as not the only factor to retard the increase of vitrinite reflectance (R
o). Apart from the types of the organic matter, the physical environment (temperature and pressure) and chemical environment
(fluid composition and inorganic elements) will result in the abnormal vitrinite reflectance values in the sedimentary basins.
This paper tested trace elements and vitrinite reflectance data from the the abnormal high pressure and normal pressure strata
profiles, respectively, and found that the acidic and lower salinity starta are favorable for the increase of R
o. By discussing the corresponding relationship between the contents of some trace elements in the mudstone and the vitrinite
reflectance values, the typical trace elements were found to suppress and/or catalyze the vitrinite reflectance of organic
matter, while the elements of Ca, Mn, Sr, B, Ba and P may result in the retardation of R
o. However, elements of Fe, Co, Zn, Ni and Rb may catalyze the organic matter maturation. This study is conductive to the organic
maturation correction, oil and gas assessment and thermal history reconstruction by the paleothermometry.
Translated from Acta Geologica Sinica, 2006, 80(11): 1760–1769 [译自: 地质学报] 相似文献
15.
《International Journal of Coal Geology》2005,61(3-4):223-239
The aim of this study was first to review or even identify reliable diagnostic criteria to distinguish recycled and autochthonous vitrinite particles and, second, to examine and try to explain the impact of weathering and reburial on optical changes (reflectance) of recycled material. The work was based on indigenous and recycled particles of two sample sets from two wells drilled in the Senegalese margin basin and the Ardèche paleomargin (SE France), respectively. In addition to reflectance measurements, the studied samples have also been analysed by Rock-Eval pyrolysis. For both sample sets, hydrogen index (HI) and oxygen index (OI) values suggest a type III organic matter of dominant terrestrial origin.Two main diagnostic criteria appear particularly useful to identify indigenous and recycled vitrinite particles: the first is the clear genetic relationship between telinite and collotelinite; the second is the presence of pyrite framboid inclusions in indigenous vitrinite. The pyrite–vitrinite association illustrates the relationship between sulphate reduction, pyritisation, and in situ organic matter transformation through gelification process. However, application of both diagnostic criteria requires some additional information about depositional conditions (i.e., anoxicity) and thermal maturity of the studied samples. Weathering has no or only very limited effect on vitrinite reflectance. During their new burial history, recycled vitrinites follow a reflectance evolution path close to that of inertinites and thus appear as transitional materials between vitrinite and inertinite macerals. Consistently, this behaviour implies that recycled vitrinite reflectance changes during burial diagenesis do not solely depend on their chemical composition but, most probably too, on combined chemical and structural changes inherited from their past burial history and from the impact of weathering during their recycling stage. 相似文献
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Multiple thermal indicator tomography is a non-linear inversion procedure which permits simultaneous determination of geological, chemical kinetic, and thermal parameters in the burial and thermal histories of sediments. The procedure is based on inverting measurements with depth in a well of multiple thermal indicators, each of which must have experienced the same thermal history. For two wells from diverse geological settings, tomography is used to assess the paleoheat-flux variations with time most consistent with all the thermal indicator data. Resolution and sensitivity of the results are also addressed. For the case history of well X in the North Sea, with both vitrinite reflectance and sterane isomer thermal indicators, a generally decreasing heat flux from past to present is obtained roughly halving every 50 Ma. The activation energy for the sterane isomer is also determined simultaneously to be 42±20 kJ/mole. For the second case history of the Irma Mclean well in the onshore Gulf of Mexico, data from four thermal indicators are available: vitrinite reflectance, sterane and hopane isomers, and sterane aromaticity. A general decrease in paleoheat-flux from amount 2.8 heat flux units (HFU) at 100 MaBP to 1.25 HFU at the present day is obtained, the activation energy for the sterane isomer is simultaneously determined to be around 50±20 kJ/mole, while the corresponding values are around 80±20 kJ/mole for the hopane isomer, and around 65±20 kJ/mole for sterane aromatization. 相似文献
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The objective of the study was to characterize changes of reflectance, reflectance anisotropy and reflectance indicating surface (RIS) shape of vitrinite, sporinite and semifusinite subjected to thermal treatment under inert conditions. Examination was performed on vitrinite, liptinite and inertinite concentrates prepared from channel samples of steam coal (Rr = 0.70%) and coking coal (Rr = 1.25%), collected from seam 405 of the Upper Silesian Coal Basin. The concentrates were heated at temperatures of 400–1200 °C for 1 h time in an argon atmosphere.All components examined in this study: vitrinite, sporinite and semifusinite as well as matrix of vitrinite and liptinite cokes, despite of rank of their parent coal, show, in general, the most important changes of reflectance value and optical anisotropy when heated at 500 °C, 800 °C (with the exception of bireflectance value of sporinite) and 1200 °C.After heating the steam coal at 1200 °C, the vitrinite and the semifusinite reveal similar reflectances, whereas the latter a slightly stronger anisotropy. Sporinite and matrix of liptinite coke have lower reflectances but anisotropy (Rbi and Ram values) similar to those observed for vitrinite and semifusinite. However, at 1000 °C sporinite and matrix of liptinite coke have the highest reflectivity of the studied components. The RIS at 1200 °C is the same for all components.The optical properties of the three macerals in the coking coal become similar after heating at 1000 °C. Coke obtained at 1200 °C did not contain distinguishable vitrinite grains. At 1200 °C semifusinite and vitrinite coke matrix have highest Rr values among the examined components. Maximum reflectance (Rmax) reach similar values for vitrinite and sporinite, slightly lower for semifusinite. Matrix of liptinite coke and matrix of vitrinite coke have considerably stronger anisotropy (Rbi and Ram values) than other components. RIS at 1200 °C is also similar for all components. 相似文献
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The reflectance of vitrinite (collotelinite) particles is a widely used parameter as a geothermometer for the estimation of the thermal maturity of organic matter enclosed in rocks. However, several problems have occurred during the last decades, which can be traced back to basically three causes: human mistakes, technical problems, and problems associated with the structural and compositional inhomogeneity of organic matter. Whilst in most cases the first two types of uncertainties can be handled by standardization, the third can cause significant problems during interpretation due to its generally inestimable character. The suppression of vitrinite reflectance and statistical problems originated from small sample size, and outliers belong to this latter type.International standards, such as the ASTM and the ISO, define the vitrinite reflectance parameter as a statistical average of measured data, disregarding the fact that the average is an unresisting and unrobust statistical parameter. In other words, the average is very sensitive to outliers and distribution.The aim of this research was to find and test a better, more resistant, and robust statistical parameter used by traditional parametric and nonparametric statistics, which can be applied in practice instead of the average. Three categories of statistical problems were studied on coal and disperse organic matter (DOM) samples: the distribution of measured values, the effect of data number, and the effect of outliers on statistical parameters. The statistical experiments carried out on numerous original and generated sample sets show that the median (med) and the most frequent value (Mn), a special weighted average, are better parameters to estimate the thermal maturity of organic matter especially above 1% reflectance value. 相似文献
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Vitrinite reflectance on dispersed sedimentary organic matter is traditionally determined from histograms of vitrinite and inertinite reflectance measured on either whole rock samples or kerogen concentrates, or from particles usually in whole rock preparations chosen by morphology and relative reflectance to be first-cycle vitrinite. This paper discusses an alternative method: discrimination of first-cycle vitrinite using apparent maximum and minimum reflectance data plotted on reflectance crossplots. The use of crossplots increases the confidence that the macerals identified as first-cycle vitrinite are optically similar. The maximum–minimum data, in this study, were collected on a quantitative reflectance microscope outfitted with rotational polarization, a technique that eliminates the usual difficulty in collecting such data on very small macerals by stage rotation. 相似文献
20.
沉积盆地下古生界碳酸盐岩地区热历史恢复方法探索 总被引：5，自引：0，他引：5
古温标是目前恢复沉积盆地热历史最常用方法之一,但在下古生界高过成熟碳酸盐岩由于没有合适的成熟度标定参数(古温标),对其经受的热历史和成烃史的恢复一直是困扰中国海相碳酸盐岩油气勘探的问题。目前常用的沥青反射率、牙形石色变指数、镜状体反射率等各类古温标,在用于早古生代碳酸盐岩地区的热历史恢复时都是借助于它们各自与镜质体反射率之间的关系,再利用现有的镜质体反射率模拟热历史方法来恢复热历史,因而存在不同的缺陷。重点介绍了利用有机质自由基浓度作为碳酸盐岩地区古温标的可能性。通过不同时间和温度下的热模拟得到的有机质自由基浓度数据,初步建立了三种类型有机质的自由基浓度(N)与时间-温度指数(TTI)的定量模型。这种有机质自由基浓度与TTI的关系式为碳酸盐岩地区古地温的恢复提供了新的方法。 相似文献