http://www.sciencedirect.com/science/article/pii/S1674987111000879

Multiple sets of thick coal beds characterized by simple structure and shallow burial depth were developed in the Early and Middle Jurassic strata of the Ordos Basin,northwestern China.The huge reserves of this high quality coal have a high commercial value.We studied the coal’s petrologic characteristics and its maceral distribution to determine the maceral’s contribution to generation of oil and gas.The results show that the Jurassic coals in the Ordos Basin have special penological features because of the Basin’s unique depositional environment which was mainly a series of high-stand swamps in the upper fluvial system.These petrographic features are a result of the development of typical inland lakes where some sand bodies were formed by migrating rivers.After burial,the peat continued to undergo oxidizing conditions,this process generated extensive higher inertinile contents in the coals and the vitrinite components were altered to semi-vitrinite.The macroscopic petrographic types of these Jurassic coals are mainly semi-dull coal,dull coal,semilustrous and lustrous coal.The proportions of semi-dull coal and dull coal are higher in the basin margins,especially in the area near the northern margin.The numbers of semilustrous and lustrous coals increase southwards and towards the central basin.This situation indicates that different coal-forming swamp environments have major controlling effects on the coal components.Another observation is that in the Ordos" coal sequences,especially in the lower part,some sandstone beds are thick,up to 20 m with a coarse grain size.The higher fusinite content in the macerals accompanies a higher semi-vitrinite content with more complete and regular plant cell structure.The fusinite structure is clear and well preserved.After burial,the lithology of the roof and floor rocks can continue to affect the evolution of coal petrology.The sand bodies in the roof and floor exhibit good physical conditions so that pore water can maintain a long-term state of oxidation,circulation and connection to the coal.So coal components remain in an oxidation environment for a long time.Conversely,in the basin center,lacustrine facies developed and peat was rapidly covered by mudstone after burial and subsequent coal beds rapidly entered a reducing environment.As a result,abundant gelatification occurred and the vitrinite content increased.Exinite often accumulated in a specific position in the coal bed.Although the average exinite content is not high on the whole,it does significantly contribute to the total hydrocarbon generation. The exinite content has been underestimated,especially the amorphous bituminous fluid and its importance is emphasized here.The reason is that the fluid flows easily into fusinite which has strong rigidity,or flows into some fissures,where it is commonly neglected.     

黄陵矿区2^#煤层煤岩及煤相特征分析

应用煤岩学与地球化学相结合的研究方法,探讨了黄陵矿区2#煤层的煤岩学特征及煤相类型。研究表明：2#煤层显微煤岩组分以镜质组为主,煤层从底部到顶部煤相由潮湿森林沼泽向开放沼泽过渡,包含五个次级演化层序,潮湿森林泥炭沼泽相是煤层煤相类型的主体,水动力条件较弱,成煤植物以木本植物为主,形成环境整体上为潮湿—覆水环境。     

煤及显微组分在超高温开放体系实验中动力学参数确立与天然气形成过程预测

通过对塔里木盆地煤及其显微组分以1K/min升温速率在开放体系下进行热模拟实验(Tmax=1200℃),确定了CH4与N2生成动力学参数。根据化学反应动力学原理,当煤岩生成CH4和N2为25个一级平行反应且具有相同频率因子(Ao=1.0×1013s-1)时,生成CH4与N2每个反应对应的活化能可以通过实验数据与理论计算拟合,获得Gaussian型活化能分布特征为:CH4在活化能为42～90kcal/mol内,煤、镜质组、壳质组、丝质组和半丝质组生成CH4的主频活化能分别为60、52、50、70和66kcal/mol;N2在活化能为60～108kcal/mol内,其主频活化能分别为74、108、100、108和102kcal/mol。根据这些实验动力学参数,推测了煤岩在地质升温速率为5.3K/Ma时CH4的转化率:CH4在地质温度为20℃时开始形成;当地质温度为160℃时,煤岩中CH4已生成总量的80%。镜质组和壳质组CH4转化率要高于煤岩。     

有机岩石学在油气勘探中的应用

有机岩石学是在煤岩学和孢粉学基础上发展起来的一门学科，在油气勘探和评价中已成为一种重要的研究手段。综述了有机岩石学在显微组分分类、有机质成熟度、有机质丰度、类型、成烃作用和烃类生成、运移和聚集方面的进展，讨论了流体包裹体、储层沥青在油藏地球化学方面确定油气水界面、成藏期方面的应用。提出了有机岩石学在油气勘探中的发展方向。     

黄县煤田第三纪有机岩中树脂体类型及成烃意义

黄县煤田第三纪腐殖煤、藻烛煤、油页岩显微组分富含树脂体。根据产状和光学性质，树脂体划分为３种类型。ＧＣ／ＭＳ检测结果，饱和烃和芳烃馏分中存在大量的树脂生源的生物标志物，树脂体含量与总烃浓度，树脂体类型指数与烃转化率有良好的相关性。光学显微镜下，黄县煤田有机岩中发现有渗出沥青体和油珠。研究认为，树脂体是黄县煤田有机岩早期生烃的一种重要母质。     

乌达矿区煤中显微组分有机硫的赋存分布

应用带能谱的扫描电镜微区测试对乌达矿区煤中不向显微组分的有机硫进行了系统测定，结果表明在不同的显微组分中其有机硫的含量有明显的差异，向一煤样中不同的亚组分中其有机硫的含量不相同，并且同一煤样同一显微亚组分其有机硫的含量亦有不同程度的差异。综合分析发现煤显微组分有机硫含量主要受煤的聚积环境、凝胶化程度、氧化程度等因素的影响。     

13C high resolution solid state NMR spectra of Chinese coals

Several typical exinites in China including alginite, cultinite, suberinite and bituminite are analysed by means of¹³C high solution solid state CP MAS TOSS NMR spectra to determine their chemical structures and hydrocarbon potential. Thermal simulation solid products (TSSP) of hydrogen-rich coals are studied to discuss the generation and expulsion mechanism of coal-generating hydrocarbon. The preliminary results are quite encouraging, wntaining useful information about genesis of coal-generating oil and gases. Project supported by the “85–102” Chinese National Key Science and Technology Project.     

准噶尔盆地侏罗纪煤成油研究

本文以有机岩石学和有机地球化学研究为基础，结合模拟实验，对中国西北地区准噶尔盆地侏罗纪煤成油问题进行了详细讨论，结果表明，准噶尔盆地侏罗纪煤含有丰富的类脂成分，壳质组特别是角质体含量高可能导致了本区高蜡石油的生成，壳质组和基质镜质体的含量决定了煤的氢指数和热解烃产值，它们共同构成了盆地内煤成油的母质。模拟排油实验证明了煤孔隙的吸附能力是有限的，在一定的压力条件下，煤中液态烃达到一定数量后就可以较好地排出。为了便于生产勘探，文中还讨论了煤系地层的沉积有机相，依据沉积相，有机地球化学和有机岩石学特征将煤系划分成四种沉积有机相:分别是高位沼泽有机相，森林沼泽有机相，流水沼泽有机相和开阔水体有机相，其中，流水沼泽有机相生成液态烃的潜力最大，以含有大量的角质体为特征；森林沼泽有机相的生烃潜力次之，以基质镜质体为主要成分；高位沼泽有机相生烃潜力最差，以惰性组和镜质组为主要的有机组分；而开阔水体有机相不是煤成烃研究的理想场所     

渝东南地区下古生界富有机质页岩有机岩石学特征

渝东南下古生界主要发育牛蹄塘组和五峰-龙马溪组两套富有机质页岩:五峰-龙马溪组岩心样品显微组分总含量TMC值为0.6%~1.2%,牛蹄塘组岩样TMC值为0.7%~2.2%。页岩富氢显微组分主要为腐泥组和壳质组,其中矿物沥青基质、藻类体和壳屑体是下古生界页岩主要生烃组分,对油气生成贡献最大渝东南下古生界富有机质页岩热演化程度处于过成熟—极高过成熟阶段,等效镜质体反射率(VR_O)为2.25%~5.18%。本文应用全岩有机岩石学分析技术,系统研究了2套页岩的显微组分组成、分布特征、主要组分对生烃的贡献以及有机质热演化程度,希望为该区页岩气的勘探与开发提供进一步的证据支持。