氧化—还原条件对有机质的生烃能力及热稳定性的影响

在南华北石炭、二叠纪含煤岩系中发现了沉积—成岩阶段氧化程度逐渐加深的陆生高等植物来源的有机质系列,对该系列有机质的综合研究表明:随氧化程度加深,高等植物的类脂组分基本保持不变,而木质纤维组分可形成由镜质体到惰性体的连续系列,镜质体反射率逐渐增大,有机质的生烃能力逐渐减小,但经过高度氧化的有机质(Ⅳ型干酪根)仍具有一定的生油能力;有机质的热稳定性逐渐减弱;干酪根的碳同位素组成逐渐加重。     

沉积有机质中稳定碳同位素逆转现象初探

本文研究了沉积有机质的可溶部分（抽提物）和不溶部分（干酪根）及抽提物的族组分（饱和烃、芳烃、非烃、沥青质）的碳同位素组成特征。通过其δ13C的分布为:干酪根>抽提物;沥青质 >非烃 >芳烃 >饱和烃。研究表明由于生源物质的不同,沉积环境的差异可构沉积有机质碳同位素组成异常。如非烃 >沥青质 >芳烃 >非烃、本文称为沉积有机质碳同位素局部逆转。当沉积有机质可溶部分>干酪根时,称之为总体逆转。湖沼相或河间湖相高等植物来源常为正常组或型;经细菌强烈改造生源以高等植物为主有低等生物为类脂组分加入常形成局部逆转的碳同位素组成。总体逆转则常现于有机质演化程度很高的海相沉积岩中。     

泥页岩热模拟实验及成岩演化模式

随着泥页岩油气勘探开发的不断推进,对泥页岩的成岩作用研究越来越受到重视。通过对三种不同干酪根类型的泥页岩样品的热模拟实验发现,随着有机质成熟度的增加,干酪根热解生烃产生的有机质孔及不稳定矿物溶蚀孔增加,是泥页岩储集空间增加的主要原因;泥页岩成岩作用类型主要有黏土矿物转化、不稳定矿物溶蚀作用和重结晶作用;结合镜质体反射率,建立了基于热模拟实验的泥页岩综合成岩演化模式。研究表明:不同类型的干酪根在生烃过程中演化特征不同,Ⅰ型干酪根以"解聚型"的途径生烃,以产生有机质边缘孔为主;Ⅲ型干酪根以"平行脱官能团型"的途径生烃,以产生有机质内部孔为主;Ⅱ型干酪根介于两者之间,既可以产生有机质内部孔,也可以产生有机质边缘孔。     

如何判别干酪根裂解气与原油裂解气

<正> 过去的天然气成因研究只是指出天然气是属于腐泥型、腐殖型还是混合型。但是天然气既可来源于干酪根裂解气,也可来源于原油(包括胶质和沥青质)的裂解气,而对于腐泥型有机质,天然气绝大部分是来自于干酪根先期生成的原油的裂解气,只有少部分天然气来自于干酪根的裂解。因此,对于母质类型好的有机质,干酪根在成熟阶段生成的油能否     

可可西里卓乃湖地区五道梁群油页岩石油地质意义

对可可西里中新统五道梁群油页岩研究表明：油页岩有机质丰度中等一高;有机质类型以腐泥型（Ⅰ）-腐殖腐泥型（Ⅱ,）为主。有机质的热演化以低成熟为主;总体上为较好的烃源岩,中新世时可可西里盆地为封闭、干热的以碳酸盐岩沉积为主的盐湖盆地。封闭与还原性静水环境为有机质的堆积和转化形成油页岩提供了条件。     

干酪根的类型及其分类参数的有效性、局限性和相关性

众所周知,不同类型干酪根的成烃潜力有很大差别,且产物性质也有所不同。因此,在油气资源的评价中,正确判别干酪根的类型有着十分重要的意义。1982年,我们曾在“干酪根类型划分的X图解”一文中,在法国石油研究院分类的基础上,利用岩石热分析（ROCK-EVAL）资料把干酪根划分为三类五型,即标准腐泥型（Ⅰ₁）,含腐殖的腐泥型（Ⅰ₂）,中间型或混合型（Ⅱ）,含腐泥的腐殖型（Ⅲ₁）和标准腐殖型（Ⅲ₂）。与此相应,我国陆相沉积盆地的油源区,按主力油源层的干酪根类型,基本上可以分为五大类     

松辽盆地农安地区上白垩统油页岩含油率影响因素

农安油页岩含矿区地处松辽盆地东南隆起区,主要发育于上白垩统青山口组一段、嫩江组一、二段。油页岩有机质的干酪根类型为Ⅰ-Ⅱ₁型,质量较好,处于成岩的未成熟阶段。油页岩含油率与有机碳和氢元素含量间存在明显的线性正相关关系,当有机碳质量分数＞6％或氢质量分数＞1％时构成油页岩。此外,有机质干酪根的显微组分可以反映有机质的类型,与含油率之间也存在一定的相关性。青山口-嫩江组沉积时期,该区温暖湿润的古气候条件、大规模的海侵和缺氧事件影响了油页岩中有机质的丰度和类型,从而影响了油页岩的含油率。     

三水盆地古近系(土布)心组黑色页岩中黄铁矿的形成及其控制因素

黄铁矿是富有机质沉积的特征矿物。根据TOC/S、TOC/DOP、S/Fe关系以及S TOC Fe多重线性回归分析结果对三水盆地古近系〖HT5”,6”〗土〖KG-*3〗布〖HT5”SS〗心组红岗段黑色页岩中沉积黄铁矿的形成及其控制因素进行了分析。土布心组红岗段黑色页岩的黄铁矿有成岩黄铁矿和同生黄铁矿两种成因组分。红岗段下部（亚段A）有机碳含量普遍较低,底部水体以弱氧化条件为主,硫酸盐还原作用发生于沉积物/水界面以下,黄铁矿为成岩成因,其形成主要受有机质的限制。红岗段中上部（亚段B和C）的沉积条件变化频繁,其有机碳含量变化幅度大。富有机质（TOC>4%）岩层形成于缺氧的底部水体条件下。水体中可含H2S,碎屑铁矿物在埋藏之前即与之在水体中反应形成同生黄铁矿。这一过程不受有机质的限制,而是受活性铁与H2S接触时间的限制。同时,由于大量淡水输入导致硫酸盐浓度的降低,从而对硫化物形成有一定的限制作用。对于低有机质（TOC<4%）样品,黄铁矿由同生和成岩组分组成。其中以成岩黄铁矿为主,其形成过程主要受有机质限制,而同生黄铁矿受铁矿物与H2S接触时间的限制。     

石油及相关有机物的氢碳同位素研究

天然气和石油生成于堆积在沉积盆地中的有机质。这种物质在未固结的沉积物中受到细菌的分解而转化成含N、O和S的腐植络合物。在成岩作用过程中,这些络合物转化成干酪根——石油和天然气的母源物质。埋藏较浅的有机质一般都不成熟,仅产出细菌成因的甲烷。随着埋藏深度不断增大,通     

沉积盆地深部流体的地球化学特征及油气成藏效应初探

以济阳坳陷东营凹陷和塔里木盆地塔中地区为例，在前人深部流体研究的基础上，应用同位素地球化学、有机地球化学及热力学定量模型，对沉积盆地深部流体的活动特征及其油气成藏效应进行了初步的探讨。研究表明，在东营凹陷不仅存在着幔源富二氧化碳流体（H2O＋CO2）的活动，而且还存在着幔源富氢流体（H2O＋CH4＋H2）的活动。塔里木盆地塔中地区也发现了幔源富二氧化碳的活动。深部流体上升过程中热能传递的定量研究表明，幔源流体是良好的热能载体。东营凹陷和塔中地区的有机质异常热变现象证实了深部流体的热效应。有机质热演化生烃不仅需要热，而且是个缺氢的过程，富氢流体注入沉积盆地势必对油气的生成产生影响。加氢热模拟实验结果表明，加氢可大幅度提高烃源岩的产烃率；对腐泥型干酪根而言，加氢生烃效应最显著的阶段是在生烃高峰之后，产率可增加147％以上；腐植型干酪根的加氢生烃效应在各个阶段都较显著。在东营凹陷和塔中地区分别发现了深部流体促进烃源岩生烃的现象。因此，深部流体在能量上和物质上对油气的生成均可构成重要的影响。     

Early Cretaceous anoxic basin of the Russian Plate: Organic geochemistry

Compositions of organic matter in the bituminous shale accumulated under anoxic conditions and in the underlying clay deposited in aerated basin are noticeably different. Organic matter (OM) of the clay is depleted in hydrogen and kerogen of the clay during pyrolysis produces 2.5 times less aliphatic hydrocarbons than kerogen, which is separated from the bituminous shale, and dozens of times less sulfurous compounds, such as thiophenes and benzothiophenes. Accumulation of OM in the clay was primarily related to the direct inheritance of polymeric lipid biochemical components of the initial OM and lignin included in the higher plants. Changes of gas regime in the basin and sediments, expressed in the origin of anoxic conditions during the accumulation of bituminous shales, intensified the early diagenetic sulfuration and the consequent formation of sulfur- and hydrogen-rich kerogen in the shales. At the same time, less stable lipids and, possibly, carbohydrates were also conserved.Translated from Litologiya i Poleznye Iskopaemye, No. 1, 2005, pp. 25–34.Original Russian Text Copyright 2005 by Bushnev.     

Improvement of kerogen structural interpretations based on oxidation products isolated from aqueous solutions

A detailed investigation of kerogen oxidation products remaining in aqueous solutions after the usual isolation of degradation products by extraction with ether or precipitation, was carried out for the first time in kerogen structural studies. Three shale samples were investigated: Green River shale (type I kerogen), Toarcian shale, Paris Basin (type II), and Mannville shale, Canada (type III). The yields of acids from aqueous solutions were noticeable: 12.98, 15.32 and 22.32%, respectively, based on initial kerogens. Qualitative and quantitative capillary GC/MS analysis showed that the ratios of different kinds of identified acids depended much on the type of precursor kerogen. Some of the acids identified in aqueous solutions have not been found earlier among the degradation products of the same kerogen samples, or were obtained in different ranges and yields. Consequently, slight modifications were suggested of the image on the nature of various types of kerogens based on examination of ether-soluble acids only. Namely, slightly higher proportions of aromatic and alkane-polycarboxylic acids in the total oxidation products of both type I and type II kerogens indicated larger participation of aromatic and alicyclic and/or heterocyclic structures in these two kerogens. On the other hand, for type III Mannville shale kerogen, a somewhat larger share of aliphatic type structures was demonstrated.     

Studying of liquid thermolysis products of various types of immature kerogen in sedimentary lacustrine rocks from the valjevo-Mionica basin,Serbia, and the effect of Pt<Superscript>4+</Superscript> and Ru<Superscript>3+</Superscript> ions on their yield and the hydrocarbon composition

Liquid thermolysis products of various types of immature kerogen from sedimentary lacustrine rocks from the Valjevo-Mionica basin in Serbia were studied to evaluate the generation potential of kerogen contained in the organic matter (OM) of the rocks, determine the composition of the biomarkers and alkylaromatics in the liquid thermolysis products, and elucidate the effect of Pt⁴⁺ and Ru³⁺ ions (which were added in the form of inorganic salts) on the yield and hydrocarbon composition of the liquid thermolysis products. For this purpose, representative bitumen-free samples A and B of the sedimentary rocks were subjected to thermolysis under various conditions. Rock A contains high amount of immature organic matter, which is dominated by kerogen type I/II and was generated under strongly reduced sedimentation conditions at a high salinity. Sample B is poorer in immature OM than sample A, and the OM of the former contains kerogen type II/III and was generated predominantly in a reduced environment. The content of the liquid products and the concentrations of hydrocarbons obtained in the course of thermolysis of bitumen-free sample A and the typical oil distribution of the biomarkers and alkylaromatics in the thermolysis products confirm a high generation potential of OM in this rock. In all of our experiments on the thermolysis of bitumen-free sample B, the yield of liquid products and hydrocarbons is low. According to the kerogen type, the thermolysis of this rock generates much gases. The Pt⁴⁺ and Ru³⁺ ions (added in the form of simple inorganic salts) increased the yield of liquid (kerogen type I/II) and gaseous (kerogen type II/III) products. During the thermolysis of various type of immature kerogen in the lacustrine sedimentary rocks at a temperature of 400°C, the OM attained maturation corresponding to the early catagenesis level. Saturated biomarkers and alkylaomatics in the thermolysis products of both samples display typical oil distributions. The type of the source OM most strongly affects the composition of n-alkanes and alkylnaphthalenes. The metal ions used in this research served as catalysts for the methylation process during the thermolysis of immature kerogen, regardless of its type. The effect of the Pt⁴⁺ and Ru³⁺ ions on other transformations of the hydrocarbons, for example, the destruction of high-molecular n-alkanes to low-molecular ones and on isomerization reactions in molecules of polycyclic biomarkers and alkylaromatics to thermodynamically more stable isomers in the thermolysis products is controlled, first of all, by the type of the source OM.     

Characteristics of amorphous kerogens fractionated from terrigenous sedimentary rocks

A preliminary attempt to fractionate amorphous kerogens from terrigenous bulk kerogen by a benzene-water two phase partition method under acidic condition was made. Microscopic observation revealed that amorphous kerogens and structured kerogens were fractionated effectively by this method. Characteristics of the amorphous and structured kerogens fractionated by this method were examined by some chemical analyses and compared with those of the bulk kerogen and humic acid isolated from the same rock sample (Haizume Formation, Pleistocene, Japan). The elemental and infrared (IR) analyses showed that the amorphous kerogen fraction had the highest atomic$\text{H}\text{C}$ ratio and the lowest atomic $\text{N}\text{C}$ ratio and was the richest in aliphatic structures and carbonyl and carboxyl functional groups. Quantities of fatty acids from the saponification products of each geopolymer were in agreement with the results of elemental and IR analyses. Distribution of the fatty acids was suggestive that more animal lipids participate in the formation of amorphous kerogens because of the abundance of relatively lower molecular weight fatty acids (such as C₁₆ and C₁₈ acids) in saponification products of amorphous kerogens. On the other hand, although the amorphous kerogen fraction tends to be rich in aliphatic structures compared with bulk kerogen of the same rock samples, van Krevelen plots of elemental compositions of kerogens from the core samples (Nishiyama Oil Field, Tertiary, Japan) reveal that the amorphous kerogen fraction is not necessarily characterized by markedly high atomic $\text{H}\text{C}$ ratio. This was attributed to the oxic environment of deposition and the abundance of biodegraded terrestrial amorphous organic matter in the amorphous kerogen fraction used in this work.     

Kinetic studies of asphaltene pyrolyses and their geochemical applications

Pyrolysis kinetics are determined for a series of asphaltene samples associated with different types of kerogens. The activation energy distributions obtained for asphaltenes related to type I kerogens cover a wide range, with significant hydrocarbon generation with activation energies above 350 kJ/mol. The ranges of activation energy distributions are relatively narrow for asphaltenes associated with type II and III kerogens, with little hydrocarbons generated with activation energies above 350 kJ/mol. If the type of associated kerogen can be reasonably constrained, the pyrolysis kinetics of the asphaltenes is potentially a very useful tool for assessing the maturity levels of reservoired oils. The results of pyrolysis kinetics indicate that there is still significant potential for asphaltenes to regenerate hydrocarbons.     

珠江口盆地番禺低隆起-白云凹陷北坡干酪根热演化模拟与生烃

通过密封金管-高压釜体系对珠江口盆地番禺低隆起-白云凹陷北坡恩平组炭质泥岩的干酪根(PY),在24.1 MPa压力、20℃/hr(373.5~526℃)和2℃/h(343~489.2℃)两个升温速率条件下进行热模拟生烃实验,分析气态烃(C1 5)和液态烃(C6 14和C14+)的产率,以及沥青质和残余有机质碳同位素组成。同时与Green River页岩(GR)和Woodford泥岩(WF)的干酪根,分别代表典型的I型和II型干酪根进行对比研究。结果显示PY热演化产物中总油气量明显低于GR和WF干酪根,且气态烃(C1 5)最高产率是液态烃的1.5倍,揭示恩平组炭质泥岩主要以形成气态烃为主。在热演化过程中,有机质成熟度和母质类型是控制油气比的主要因素,气态烃和轻烃的产率比值主要受热演化成熟度的影响。干酪根残余有机质碳同位素和沥青质碳同位素在热演化过程中受有机质成熟度的影响较小,δ13C残余和δ13C沥青质可以间接反映原始母质的特征,为高演化烃源岩油气生成提供依据。     

海相成熟干酪根生气潜力评价方法研究

高成熟阶段干酪根热解氢指数（HI）非常低,在热成熟度指标镜质组反射率Ro为2.0%以上的Ⅰ或Ⅱ型有机质,一般都在20 mg/gTOC以下,甚至接近0 mg/gTOC,因此,一般认为这种干酪根生烃能力极低。本文通过对不同成熟阶段的干酪根采用元素分析和热解模拟实验相结合的方法,发现HI指数很低的高过成熟阶段干酪根仍然具有一定的生气能力,生气潜力是HI指数的数倍,如HI指数为12 mg/gTOC的样品,H/C原子比为046,生气能力仍然为65 mg/gTOC,占总生烃能力的15%左右,说明成熟—过成熟有机质HI指数不适合衡量生气潜力。同时发现,干酪根生气能力与H/C原子比具有极好相关性,相关系数达到096,通过回归公式所获得有效生气干酪根H/C原子比下限为026。     

干酪根中类脂肪链含量的测定及石油地质意义

选取了红外光谱中2750～3000cm-1C-H振动峰面积作为反映干酪根中脂肪链含量的特征参数,并以完全饱和脂肪链的微晶石蜡为基准,建立了对干酪根中脂肪链含量进行测定的实验方法,同时讨论了实验条件、无机矿物、干酪根样品加入量等因素的影响。并通过对东营地区不同类型干酪根的低熟烃源岩样品进行的高压热模拟实验,研究了干酪根中脂肪链的百分含量与成熟度、沥青转化率及干酪根原素组成之间的关系。结果表明干酪根中脂肪链含量不仅与干酪根的类型有关,而且随成熟作用增加明显降低,其与热模拟生油量的关系和烃源岩的产烃率曲线相似,在脂肪链含量由15%降至5%时出现一个生油高峰。所以,脂肪链百分含量这一参数有可能成为烃源岩的判别及评价的一个新的重要指标。     

Depositional environments of the Senonian chert, phosphorite and oil shale sequence in Israel as deduced from their organic matter composition

In the Upper Cretaceous sequence of the Negev (southern Israel) the organic matter in phosphorites and cherts differs from that associated with oil shales in its higher content of humic substances and lower kerogen content, and in its more intensive microbial alteration. The n-alkane distribution pattern of the oil shales, phosphorites and cherts indicates that marine biota, probably algae, are the main organic precursors of their organic matter. In some of the oil shales, however, some contribution of terrestrial organic matter is also evident. Similar high phytane/pristane ratios indicate that the organic matter in the oil shales as well as in the phosphorites and cherts accumulated under reducing conditions. The main differences in the organic matter composition are attributed to early diagenetic processes rather than to different biotic precursors or to late modifications due to temperature-induced maturation. The depositional model suggested for the sequence involves upwelling conditions at the boundary between the deep Tethys and the shallow shelf, which induced high organic productivity deep into the inner shelf. Bottom water circulation enabled intensive microbial alteration of the organic matter, followed by a winnowing process leading to phosphorite formation. Since humification is considered an oxygen-consuming reaction, these processes favoured the formation of oxygen-enriched humic substances and the oxidation of humic substances already present. These humic substances are relatively resistant to further alteration and their conversion into kerogen is thus retarded. Subsequently, syndepositional tectonic activity resulted in the introduction of less saline water, restriction of bottom-water circulation and the establishment of a density stratification in the water body. Consequently, aeration of the bottom layer and the sediments was inhibited, microbial alteration was reduced and later winnowing processes were prevented. Such conditions favoured the formation of kerogen directly, rather than through humic substances, and also favoured the preservation of most of the organic matter in the form of oil shale deposits instead of phosphorites.