中国海相碳酸盐岩的生烃研究

碳酸盐岩成烃有机质丰度下限值的确定,涉及到盆地实际资料的统计,以及源岩有机质类型、热成熟度、矿物组成、古地温、生储配置关系等诸多因素。提出了一种具有实验依据的高、过成熟碳酸盐岩原始有机质丰度及生烃潜力恢复法,经在我国一些盆地下古生界海相源岩中使用,效果良好。海相镜质体形成机制的研究揭示,同一生源前生物(菌、藻),因其沉积环境和演化途径不同,可形成地化性质完全不同的地质聚合物。首次提出了利用固体~(13)C 核磁共振波谱获得的干酪根中的芳核平均结构尺寸 X_b 作为前泥盆纪碳酸盐岩有机质热成熟度的新衡量标尺。自然演化与热压模拟两个系列的对比研究表明:脂族碳是干酪根热降解成烃的主要贡献者,油潜力碳在热演化过程中呈“三段式”的阶段变化特征。利用固体~(13)C 核磁共振波谱所提供的不同母质类型和不同演化阶段干酪根中各类结构组成的碳分数变化特征,不仅可揭示油气生成机制及过程,还可对各类源岩生成油气的定量研究提供新的途径。     

核磁共振芳碳率作为成熟度指标的有效性讨论

石油地质学中,寻找油窗范围内较为有效的成熟度指标一直是油气地球化学家致力研究的科学问题之一。随着固体核磁共振技术在干酪根地球化学上的应用及发展,芳碳率被认为是具有潜力的有效成熟度指标。为对该问题进行深入探讨,对茂名盆地油柑窝组油页岩干酪根进行了高温高压黄金管热解实验,对生烃后的干酪根残渣进行了~(13)C DP/MAS核磁共振定量分析,并与美国绿河油页岩干酪根芳碳率的热演化特征进行对比;还调研了Ⅱ型及Ⅲ型干酪根芳碳率的热演化特征。结果显示,干酪根芳碳率均随成熟度的增加而增大,但不同类型干酪根的芳碳率的增长模式不同。未成熟阶段,芳碳率可以用来区分干酪根类型;生烃高峰之前,芳碳率随热成熟度增加而显著增加,可以用来指示成熟度,但与Ro关系要因类型而异;生烃高峰之后,不同干酪根的芳碳率演化趋于一致,若用来指示成熟度对NMR测试精度要求较高。若要得到精确的成熟度数据,最好建立研究区相关类型干酪根的芳碳率热演化曲线。     

干酪根的X射线衍射研究

本文讨论了干酪根X射线衍射（XRD）数据的处理方法,XRD的002峰参数t₀₀₂与化学结构参数芳碳率f_芳的关系及其计算;根据XRD谱图,研究了抚顺、茂名油页岩未成熟干酪根的化学结构。在干酪根的人工热模拟过程中,发现XRD参数t₀₀₂与芳核C轴高度L_c均随干酪根的类型和成熟度不同而变化,据此提出了不同类型干酪根的XRD(f₀₀₂-L_c)演化途经图。该图可以帮助我们判别干酪根的类型与成熟度。     

干酪根结构中碳分布特征及其与生烃潜力的关系──~（13）C NMR CP／MAS 与DD技术的应用

用常规的固体~（１３）ＣＮＭＲ谱与偶极相移谱（ＤＤ）分析研究了大庆地区不同类型低成熟干酪根的结构特征。Ｉ型干酪根ＤＤ谱的主要特征为脂碳中有明显的柔性可动的链亚甲基与次甲基峰，而Ⅲ型干酪很则以甲基信号为主。将不同结构的脂碳与干酪根的生烃潜力（由岩石评价仪测定的Ｓ值）相关联，发现亚甲基与次甲基的相关系数最高，甲基次之，ａ位亚甲基与季碳又次之，氧接脂碳对生烃的贡献不大。     

煤系源岩倾油倾气性研究

利用固体13C核磁共振波谱检测源岩干酪根中油、气潜力碳的相对含量,并利用该参数直接判别各类源岩在"液态窗"阶段的倾油、倾气性.有些煤系源岩虽然其地球化学特征属腐植型母质,但由于其干酪根的脂碳中油潜力碳>气潜力碳,故仍以生油为主.该方法从生烃机理出发进一步揭示了新疆焉耆盆地中、下侏罗统煤系源岩以生油为主的根本原因.     

干酪根分子结构在低熟阶段的演化特征：基于红外光谱分析

为研究低熟气形成过程中大分子结构的变化情况,对吐哈盆地侏罗系八道湾组的煤与碳质泥岩干酪根在不同升温速率下进行了热解实验,借助于红外光谱分析,研究了不同热模拟温度下干酪根结构的特征与变化。结果表明,随热演化的进行,煤与碳质泥岩干酪根的芳香结构不断缩合,含氧官能团不断脱落,碳质泥岩干酪根中的脂肪族类有所降低。吐哈盆地低熟气主要来源于煤与碳质泥岩干酪根中的含氧官能团--羧基与甲氧基,以及碳质泥岩干酪根上的脂肪族。从干酪根结构上揭示了低熟气主要来源于Ⅲ型有机质的原因。     

碱溶性干酪根的成分结构及其对菲的吸附的影响

选取一个含II型干酪根的页岩样品,使用一系列化学分级提取方法对其进行分级,得到原始干酪根(BK)、溶剂处理干酪根(SEK)级分、分别在20°C、40°C和60°C温度条件下连续提取碱溶性干酪根(EKs)级分和碱难溶性干酪根(RK)级分。应用一系列表征手段包括元素分析、稳定碳同位素组成分析、X射线光电子光谱、表面积和孔径分析以及先进的固态核磁共振技术对这些不同干酪根级分进行了系统地表征,着重探讨不同干酪根级分的化学结构组成的差异,以及其结构组成与它们对菲的吸附行为的关系。研究表明20、40和60°C下连续43次提取的EKs级分占原始干酪根的比例(总产量)分别为10.47%、20.60%和27.9%,表明有相当比例的干酪根是碱性可溶解的,且温度是影响干酪根溶解的一个重要因素。本研究发现了干酪根在碱性条件下是可以逐步溶解的新现象。EKs中干酪根芳香基团含量(芳香C-C、C-H和C-O)占主导地位,其占总碳的60%以上。EKs的结构组成明显与原始干酪根(BK)、碱难溶性干酪根(RK60)和溶剂处理干酪根(SEK)不同,后者以脂肪碳占主导。EKs中的芳香基团较脂肪基团更容易溶解在碱性溶液中,因而芳香碳含量高的EKs级分易于被提取,脂肪碳含量相对较难溶解在碱性溶液中难于被提取。相对于BK,碱性提取后的RK60中芳香碳含量降低,溶剂提取后的SEK中非极性脂肪碳含量稍微降低。本研究提供新的证据证明了干酪根的超分子结构的观点,表明它主要是依靠弱相互作用(包括范德华力、π-π、δ-π键和氢键)稳定地存在。二氧化碳气体吸附数据表明EKs的比表面积和微孔体积明显大于其BK和RK60。后被提取出来的EKs比先被提取的EKs对菲的吸附非线性更强,且具有更强的吸附能力,说明BK中相对极性、吸附能力相对较弱的EKs级分先被提取。EKs对菲的吸附行为明显与BK、RK60和SEK不同。相对于BK而言,碱提取后的RK60的吸附能力降低;而溶剂提取后,SEK的吸附能力增强。EKs的吸附能力与其H/C比值以及与非极性脂肪碳含量呈正比,但是与总芳香碳含量和O/C比值呈反比;吸附非线性因子(n)与非极性脂肪碳含量呈反比,而与非质子芳香碳含量呈正比。这表明非极性脂肪碳含量越高,非质子芳香碳含量越低,吸附能力越强,吸附非线性也越强。EKs对菲的吸附能力与比表面积以及微孔体积呈正相关关系,说明微孔吸附的潜在重要性。     

TiO2/浮石复合材料降解有机污染物亚甲基蓝的实验研究

利用天然浮石的孔隙结构和小比重等特点,以浮石为原料、TiOSO4为TiO2前驱体,采用水热合成法,在200℃、15 h条件下,制备出可漂浮的TiO2/浮石复合材料.采用10×10-5mol/L亚甲基蓝水溶液,在紫外光下进行光催化实验.并用紫外可见分光光度计检测亚甲基蓝浓度变化.实验结果表明,TiO2/浮石复合材料能够降解亚甲基蓝.该材料的孔隙结构对亚甲基蓝有聚集作用,促进了负载的TiO2的光催化性能的发挥.因为成本低廉,性能优越,TiO2/浮石复合材料在有机污染物治理方面具有很大的应用潜力.     

松辽盆地原油的核磁共振(NMR)谱及其有机地球化学特征

松辽盆地原油核磁共振(NMR)谱的分布特征表明,原油可划分为四种类型。原油平均分子结构参数(C_(Ar)、C_N、Cp,H_Ar、H_N、H_p,CH、CH_2、CH_3)反映了松辽盆地原油由腐殖型和腐泥型(或腐殖腐泥型)干酪根生成。随成熟度增加,原油的芳碳(C_(Ar))结构减少;多环烷烃向链烷烃和单环烷烃转化,表现为环烷次甲基碳(CH_(1-2))含量降低;链烷碳(C_P)和链烷次甲基碳(CH_(1-1))含量有增大趋势。 这些结构演化特征为研究原油的成熟度提供了有益的信息。     

利用干酪根固体^13C核磁共振法研究下古生界碳酸盐岩的热演化程度

应用固体＾１３Ｃ－ＮＭＲ技术对下古生界,海相碳酸盐岩干酪根的化学组成和结构特征进行研究,提出应用该技术所测算的干酪结构参数“芳核平均结构尺寸”能较准确地反映碳酸盐岩的热成熟度。首次提出芳核平均结构尺寸与镜质体反射率之间的关系在干酪根的热演化过程中具有“三段式”特征。利用这一成果对华北地区下古生界成熟度进行了测定,与地质背影甚为吻合。     

Comparison of oil shales and kerogen concentrates by 13C nuclear magnetic resonance

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.     

Comparison of oil shales and kerogen concentrates by C nuclear magnetic resonance

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.     

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.     

Chemical characterization of the kerogen from Moroccan Timahdit oil shale by analysis of oxidation products

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.     

Exploitation of relaxation in cross-polarization nuclear magnetic resonance spectroscopy of fossil fuels

The judicious choice of dipolar dephasing times or carbon magnetization holding times has been shown to improve resolution in solid state nuclear magnetic resonance (NMR) spectra of complex materials. Signals from protonated and alkylated aromatic carbons are reduced to enhance resolution of aromatic oxygenated groups. Rapidly rotating methyl groups can be resolved from other aliphatic carbon types. These techniques were used to investigate the structure of a brown coal, xylite fractions of a brown coal, a bituminous coal, an oil shale and a solvent-refined coal. The results allow estimates of the fraction of aromatic carbon that is protonated in coal to be made, and demonstrate that methyl groups in coal rotate rapidly at room temperature.     

Solid state C NMR studies of selected oil shales from Queensland, Australia

Solid state ¹³C NMR techniques of cross polarization with magic-angle spinning, and interrupted decoupling have been employed to examine the nature of the organic matter in eight kerogen concentrates representing five Tertiary deposits in Queensland, Australia. The NMR results show that five of the kerogens have high proportions of aliphatic carbon in their organic matter and correspond to Type I–II algal kerogens. Three of the kerogens, derived from carbonaceous shales, have a high proportion of aromatic carbon in their organic matter and correspond to Type III kerogens. The fractions of aliphatic carbon in all the kerogens, regardless of type, are shown to correlate with the conversion characteristics of the corresponding raw shales during Fischer assay. Interrupted decoupling NMR results show the presence of more oxygen-substituted carbon in the carbonaceous shales, which may account for the greater CO₂ evolution and phenolic materials found in the pyrolysis products of the carbonaceous shales.     

Characterization of Bulgarian oil shale kerogen revealed by oxidative degradation

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.     

Changes in the composition of bitumen extracts and chemical structure of kerogen during hydrous pyrolysis

The paper presents data on the composition of biomarkers from bitumen extracts and the chemical structure of kerogen from C_org-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 PC_2–3 to MC_1–2. The ¹³C NMR data on kerogen indicate that the aromatic structures of geopolymers underwent significant changes.     

Pyrolysis-high resolution gas chromatography and pyrolysis gas chromatography-mass spectrometry of kerogens and kerogen precursors

A series of kerogens and kerogen precursors isolated from DSDP samples, oil shales and Recent algal mats have been examined by Curie point pyrolysis-high resolution gas chromatography and gas chromatography-mass spectrometry. This study has shown that the three main types of kerogens (marine, terrestrial and mixtures of both) can be characterized using these techniques. The marine (algal) kerogens yield principally aliphatic products and the terrestrial kerogens yield more aromatic and phenolic products with some n-alkanes and n-alkenes. The yields of n-alkanes and n-alkenes increase and phenols decrease with increasing geologic age, however, pyrolysis-GC cannot be used to characterize the influence of short term diagenesis on the kerogen structure.     

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。