Release of organic nitrogen compounds from Kerogen via catalytic hydropyrolysis

High hydrogen pressure pyrolysis (hydropyrolysis) was performed on samples of solvent extracted Kimmeridge Clay Formation source rock with a maturity equivalent to ca. 0.35% vitrinite reflectance. We describe the types and distributions of organic nitrogen compounds in the pyrolysis products (hydropyrolysates) using GC-MS. Compounds identified included alkyl-substituted indoles, carbazoles, benzocarbazoles, quinolines and benzoquinolines. The distributions of the isomers of methylcarbazoles, C₂-alkylcarbazoles and benzocarbazoles in the hydropyrolysates were compared to a typical North Sea oil. The hydropyrolysates compared to the North Sea oil, showed increased contributions from alkylcarbazole isomers where the nitrogen group is "exposed" (no alkyl substituents adjacent to the nitrogen functionality) and appreciable levels of benzo[b]carbazole relative to benzo[a]- and benzo[c]carbazoles. Hydropyrolysis is found to be an ideal technique for liberating appreciable quantities of heterocyclic organic nitrogen compounds from geomacromolecules. The products released from the immature Kimmeridge Clay are thought to represent a potential source of nitrogen compounds in the bound phase (kerogen) able to contribute to the free bitumen phase during catagenesis.     

Geochemical characteristics and microbial populations of Neogene brown coal from Zhaotong Basin, China

For the first time in China, a preliminary survey of geochemical characteristics and microbial populations of Neogene brown coal from Zhaotong Basin in Yunnan province, China was conducted to provide a basis for an understanding of the generation of biogenic coal-bed methane in this basin. Coals in this region consist of soft brown coal with lower maturity and good bioactivity, as determined by coal petrologic measurements. Soluble organic matter in coal exhibits the characteristics of unsaturated humic hydrocarbon source rock. Organics in coal were generally associated with higher plants and lower grade aquatic organisms. The bacterial community was dominated by fermentation bacteria, and sulfate-reducing bacteria were relatively rare.     

煤成烃研究现状及应用——以三江盆地绥滨坳陷为例

阐述了煤系陆源有机质烃源岩特征和研究方法，对三江盆地绥滨坳陷白垩系穆棱－城子河组的煤系陆源有机质丰度，岩石热解参数和显微组分成烃性能进行了初步探讨，确定了该坳陷煤源岩的生烃级别。同时强调将煤系有机质源岩岩石学显微组分研究和建立东北地区煤成烃划分标准作为未来煤成烃研究的主攻方向。     

全岩热模拟新方法及其在气源岩评价中的应用

由中国石油勘探开发研究院廊坊分院建立的全岩热模拟仪器分析方法是采用岩心样品(岩石颗粒0.5～2 mm)来模拟烃类生成的一项实验新技术.该方法模拟结果表明:(1)不同类型样品单位质量岩石的产气率与传统的加水温压模拟法结果具有可比性;(2)能够反映源岩在不同演化阶段的产气量;(3)比常规的有机碳评价方法能更准确地反映源岩在不同演化阶段的产气潜力.(4)全岩热模拟新方法经济、简便、分析周期短,可以用于大量常规样品分析,是判识有效气源岩及定量评价的一种快速、可靠的方法,在油气勘探过程中,将对烃源岩的评价发挥重要作用。     

弱氧化气氛下烟煤热解特性及热解产物组成

为提高轻质焦油和煤气产率,选取陕西红柳林烟煤为研究对象,采用固定床反应器对比分析N₂气氛和弱氧气氛下（N₂+O₂）煤的热解产物产率分布及组成特性。结果表明:随着O₂的加入,半焦和焦油产率显著降低,CO和CO₂气体产率显著增大,导致总气体产率增大;由于发生氧化燃烧反应,随着热解气氛中氧含量的增大,H₂、CH₄和C₂—C₃产率逐渐降低,在此过程中水产率变化幅度较小;弱氧气氛下焦油分解温度大于N₂气氛,酚类物、脂肪烃及苯系物在弱氧气氛下热解焦油中的相对含量较低,且多环芳烃相对含量明显大于N₂气氛下热解焦油。当热解温度为800℃,过量空气系数ER=0.14时,焦油产率为6.22%,H₂产率14.01 mg/L,焦油和H₂产率达到最佳值。由于弱氧气氛下热解得到半焦的石墨化程度低于N₂气氛下的热解半焦,导致弱氧气氛下半焦反应活性大于N₂气氛。研究结果为固定床热解烟煤制备高值燃料提供基础数据。      

Gaseous hydrocarbons generated during pyrolysis of petroleum source rocks using unconventional grain-size: implications for natural gas composition

Open-system pyrolysis experiments were performed on a suite of immature to marginally mature source rocks to investigate the influence of kerogen type on primary gas composition and the effect of grain size on gas expulsion characteristics. The pyrolysis of rock powders confirmed that hydrogen-rich kerogens yielded wetter gases than did hydrogen-poor kerogens. Gases detected from the pyrolysis of rock chips were drier than those from powders of equivalent samples. This was due to two processes: the retention and secondary cracking of higher molecular weight pyrolysis products and the preferential expulsion of methane from the rock matrix. These two effects, one chemical the other physical, could be distinguished using a novel approach involving multi-step pyrolysis of rock chips followed by on-line crushing of the residues. The enrichment of methane in natural gas attributed, by earlier workers, to be a consequence of fractionation during secondary migration (post-expulsion) has been proven to be real also during expulsion from source rocks at least for pyrolysis conditions.     

Catabolic and anabolic energy for chemolithoautotrophs in deep-sea hydrothermal systems hosted in different rock types

Active deep-sea hydrothermal vents are hosted by a range of different rock types, including basalt, peridotite, and felsic rocks. The associated hydrothermal fluids exhibit substantial chemical variability, which is largely attributable to compositional differences among the underlying host rocks. Numerical models were used to evaluate the energetics of seven inorganic redox reactions (potential catabolisms of chemolithoautotrophs) and numerous biomolecule synthesis reactions (anabolism) in a representative sampling of these systems, where chemical gradients are established by mixing hydrothermal fluid with seawater. The wide ranging fluid compositions dictate demonstrable differences in Gibbs energies (ΔG_r) of these catabolic and anabolic reactions in three peridotite-hosted, six basalt-hosted, one troctolite-basalt hybrid, and two felsic rock-hosted systems. In peridotite-hosted systems at low to moderate temperatures (<∼45 °C) and high seawater:hydrothermal fluid (SW:HF) mixing ratios (>10), hydrogen oxidation yields the most catabolic energy, but the oxidation of methane, ferrous iron, and sulfide can also be moderately exergonic. At higher temperatures, and consequent SW:HF mixing ratios <10, anaerobic processes dominate the energy landscape; sulfate reduction and methanogenesis are more exergonic than any of the aerobic respiration reactions. By comparison, in the basalt-hosted and felsic rock-hosted systems, sulfide oxidation was the predominant catabolic energy source at all temperatures (and SW:HF ratios) considered. The energetics of catabolism at the troctolite-basalt hybrid system were intermediate to these extremes. Reaction energetics for anabolism in chemolithoautotrophs—represented here by the synthesis of amino acids, nucleotides, fatty acids, saccharides, and amines—were generally most favorable at moderate temperatures (22-32 °C) and corresponding SW:HF mixing ratios (∼15). In peridotite-hosted and the troctolite-basalt hybrid systems, ΔG_r for primary biomass synthesis yielded up to ∼900 J per g dry cell mass. The energetics of anabolism in basalt- and felsic rock-hosted systems were far less favorable. The results suggest that in peridotite-hosted (and troctolite-basalt hybrid) systems, compared with their basalt (and felsic rock) counterparts, microbial catabolic strategies—and consequently variations in microbial phylotypes—may be far more diverse and some biomass synthesis may yield energy rather than imposing a high energetic cost.     

西湖凹陷平湖组不同煤系烃源岩热解生烃差异及其在油气勘探中的应用

本文以西湖凹陷平湖组不同煤系烃源岩（煤、炭质泥岩和暗色泥岩）为研究对象,通过封闭体系黄金管-高压釜生烃动力热模拟实验,查明了3种煤系烃源岩生烃产物、产率特征及生烃演化规律的差异。研究结果表明：在西湖凹陷平湖组煤系烃源岩中,煤、炭质泥岩和暗色泥岩均具有很高的产气态烃能力和较高的产液态烃能力,但不同岩性样品的生烃演化模式存在一定差异。炭质泥岩生烃最早,生烃强度最大;煤居次,生烃稍晚,生烃强度稍低;暗色泥岩生烃最晚,生烃强度最低。根据热解生烃特征,指出西湖凹陷具有煤成油的勘探潜力,西部斜坡带是找油的有利区域。     

Geochemical Characteristics and Sedimentary Control of Pinghu Formation (Eocene) Coal‐bearing Source Rocks in Xihu Depression,East China Sea Basin

Coal-bearing source rocks of the Pinghu Formation in the Xihu Depression comprise an important material basis of oil and gas resources in the East China Sea Basin.Based on drilling core observation results combined with the analysis and test results of macerals,trace/rare earth elements,and rock pyrolysis,the geochemical characteristics and sedimentary control of coal-bearing source rocks formation are discussed in a high-frequency sequence framework.The results indicate that the macerals composition of the coal-bearing source rocks of the Eocene Pinghu Formation in the Xihu Depression is dominated by vitrinite,with low-medium abundance of exinite and almost no inertinite.The coals and carbonaceous mudstones display higher amounts of total organic carbon(TOC)(14.90%-65.10%),S1+S2(39.24-136.52 mg/g),and IH(191-310 HC/g TOC)respectively,as compared to the mudstones.Organic matter is plotted in typeⅢkerogens and partially in typeⅡ;it is mainly in the low maturity stage.The trace elements results imply that the samples were deposited in a weakly reducing to weakly oxidizing environment and were occasionally affected by seawater.The coal-bearing source rocks were deposited in a relatively oxygen-containing environment.The coal-bearing source rocks development is jointly controlled by the coal accumulation environment,the water conditions affected by ocean currents in offshore basins in China,oxidation-reduction cycles of aqueous media and paleoclimate evolution in a high-frequency sequence framework.     

煤成烃生成及排驱加水热模拟实验

用加水热模拟实验对采于我国胜利油田附近的石炭系太原组亮褐煤（R0＝0．56%）生烃潜力进行研究。煤样富含镜质组（74．5%）,壳质组少（8．8%）,惰性组占16．7%,其中镜质组以富氢的基质镜质体为主。煤样裂隙发育,形成于滨海沼泽相沉积环境。实验设200℃、230℃、260℃、290℃、320℃和350℃六个温度点,每个温度点加热72小时。实验结果表明该煤具有较高的生烃潜力和排油效率。其液态烃大量生成和排出始于R0＝0．76%（290℃）,在R0＝1．18%（320℃）时达高峰。气态产物从R0＝1．18%大量形成,直到R0＝1．53%（350℃）继续增大。实验分析认为煤的生烃能力除了与其有机质类型、有机质丰度等有关外,还与其形成的沉积环境有关,缺氧的还原环境是煤作为烃源岩形成和保存的有利沉积环境。裂隙的发育有助于煤成油的排驱和运移。     

煤热解气体主产物及热解动力学分析

为了研究不同煤化程度煤的热解气相产物、热解动力参数,采用热重-红外光谱-质谱（TG-IR-MS）联用技术对4种不同热演化程度的煤进行了热解实验。实时记录了4种煤样在30~1 100℃、10/min℃升温速率、氦气气氛下热解过程中释放的各种气体成分及其释放量的变化趋势。研究结果表明,随煤热演化程度升高,煤的失重率和最大失重速率逐渐降低,与煤的干燥无灰基挥发分呈正相关关系;随着热解温度的升高,煤中逐渐释放出水、甲烷、二氧化碳、氢气和二氧化硫等小分子气体,且随着煤化程度的升高,各种气体的释放峰逐渐向高温处偏移,说明煤的热稳定性逐渐升高。不同变质程度煤的热解动力学分析结果表明,随着煤变质程度增高,其活化能逐渐降低,说明其热效应强度和发生热解反应的能力在逐渐降低。      

泥炭的热模拟实验及其在煤层气研究中的应用

采用高温高压多冷阱热解实验装置,在温度和压力分别为336.8~600℃和 50MPa,升温速率为 20℃/h和 2℃/h条件下,对泥炭进行了热解生气的模拟实验,获得了烃类甲烷和C₂-C₅气体以及非烃二氧化碳、氢气和硫化氢气体的产率和体积分数数据,研究了热模拟产物气体的组分特征和热演化过程。结果表明,泥炭高温热解产物气体主要由非烃二氧化碳气体组成,其次为烃类甲烷和C₂-C₅气体。随着实验温度的增高,非烃气体体积分数呈下降趋势,烃类气体体积分数呈上升趋势。不同升温速率实验条件下,泥炭样品热解生气表现出不同的特征,主要体现了时间因素控制着泥炭的生烃过程和生烃量,这符合化学反应动力学时间与温度之间互补的原理。并且与煤岩热解生气特征进行了对比,表明泥炭比煤岩具有更高的产烃气能力。根据热模拟实验研究结果,探讨了煤层气形成方面的地球化学意义。      

Organic matter and deposition conditions of the Kashpir oil shales

The composition of organic matter was investigated in the oil shales and country rocks of the Kashpir deposit. The analysis of the aromatic fraction of bitumen showed the presence of isorenieratene derivatives, which indicates the accumulation of the sequence under anoxic conditions in the bottom waters of a paleobasin. Special attention was given to the composition of organosulfur compounds from the bitumen of rocks and products of kerogen pyrolysis. The concentrations of hydrocarbon structures occurring in the bitumen in a free state and in sulfur-bearing derivatives are comparable. The composition of the pyrolysis products of kerogen depends on the concentration of organic carbon in the rock: carbon-rich rock varieties contain kerogen whose pyrolysis yields relatively high concentrations of organosulfur compounds and low total contents of n-alkanes/n-alkenes-1.     

煤岩显微组份和全煤热解色谱分析

随着石油勘探的深入和发展，煤和含煤沉积的生油问题，已经越来越引起人们的重视。为此，笔者选择了准噶尔盆地侏罗系富氢组份含量高的煤样和富镜质组的煤岩样品，采用快速热解法，对其显微组份和全煤的热解生烃潜势进行了研究。结果表明:（１）Ｒ_０值为０.３７～０.３９％的未成熟煤岩样品中，壳质组和镜质组在３５０～４５０℃温度区间有最大热解峰面积Ｓ_２。（２）富氢组份含量高的样品中，热解产物以正构烷烃＋正构烯烃为主，其次为芳烃化合物。（３）镜质组或富镜质组的煤岩样品中，Ａ１６００/Ｍｇ值较高时，热解产物在Ｃ_６-Ｃ_１５范围内，某些芳烃化合物成为主峰。（４）惰性组生烃能力最差，在较高温度下，形成含量很低的正构烷烃和烯烃，或在气态烃范畴产生少量烃类，或基本不产生热解产物。（５）随着加热时间的延长或原煤样品演化程度的升高，烯烃含量减少或消失，可能是干酪根转化过程中的残余氢为烯烃的氢化作用提供了氢源，使烯烃转化为烷烃的缘故。     

Metamorphic assemblages and the direction of flow of metamorphic fluids in four instances of serpentinization

Fluids related to Serpentinization are of at least three types. The first reported (Barnes and O'Neil, 1969) is a fluid of local meteoric origin, the chemical and thermodynamic properties of which are entirely controlled by olivine, orthopyroxene, brucite, and serpentine reactions. It is a Ca⁺²-OH^–1 type and is shown experimentally to be capable of reacting with albite to yield calcium hydroxy silicates. Rodingites may form where the Ca⁺²-OH^–1 type waters flow across the ultramafic contact and react with siliceous country rock.The second type of fluid has its chemical composition largely controlled before it enters the ultramafic rocks, but reactions within the ultramafic rocks fix the thermodynamic properties by reactions of orthopyroxene, olivine, calcite, brucite, and serpentine. The precipitation of brucite from this fluid clearly shows that fluid flow allows reaction products to be deposited at a distance from the point of solution. Thus, textural evidence for volume relations during Serpentinization may not be valid.The third type of fluid has its chemical properties fixed in part before the reactions with ultramafic rocks, in part by the reactions of orthopyroxene, olivine, and serpentine and in part by reactions with siliceous country rock at the contact. The reactions of the ultramafic rock and country rock with the fluid must be contemporaneous and require flow to be along the contact. This third type of fluid is grossly supersaturated with talc and tremolite, both found along the contact. The occurrence of magadiite, kenyaite, mountainite, and rhodesite along the contact is probably due to a late stage low-temperature reaction of fluids of the same thermodynamic properties as those that formed the talc and tremolite at higher temperatures. Oxygen isotope analyses of some of these minerals supports this conclusion.Rodingites form from Ca⁺²-rich fluids flowing across the contact; talc and tremolite form from silica-rich fluids flowing along the contact.Isotopic analyses of the fluids indicate varied origins including unaltered local meteoric water and connate water. Complexion Spring water may be a sample of only slightly altered Jurassic or Cretaceous sea water.Publication authorized by the Director, U.S. Geological Survey.     

冀中坳陷东北部石炭-二叠系烃源岩生烃潜力评价

冀中坳陷东北部石炭-二叠系煤系地层生、储、盖组合条件完备,上古生界自生自储煤成气藏勘探潜力巨大。笔者基于该层系"油井少、空井多"的勘探现实,通过烃源岩热解数据分析和热模拟实验工作,评价区内烃源岩的生烃潜力,以期减少勘探风险。数据分析表明,w(TOC)为10%和40%是区内煤系暗色泥岩、炭质泥岩和煤岩的有效划分界限。区内石炭-二叠系煤系烃源岩主要以Ⅲ型干酪根为主,为中等较差的油源岩和较好的气源岩。分别受岩浆热变质和深成变质作用影响,区内存在武清凹陷、苏4-苏8-苏23-文古4和葛8-大参1三个成熟度高值区,即生油气中心。结合热模拟实验结果,采用体积法算得该区石炭-二叠系地层生气总量约为4万亿m3。     

Biomass burning — a review of organic tracers for smoke from incomplete combustion

Biomass combustion is an important primary source of particles with adsorbed biomarker compounds in the global atmosphere. The introduction of natural product organic compounds into smoke occurs primarily by direct volatilization/steam stripping and by thermal alteration based on combustion temperature. Although the molecular compositions of organic matter in smoke particles are highly variable, the molecular tracers are generally still source specific. Dehydroabietic acid is typically the major tracer for conifer smoke in the atmosphere. Degradation products from biopolymers (e.g. levoglucosan from cellulose, methoxyphenols from lignin) are also excellent tracers. Additional markers of thermally-altered and directly-emitted natural products in smoke have been defined which aids the assessment of the organic matter types and input from biomass combustion to aerosols. The precursor to product approach of compound characterization by organic geochemistry has also been applied successfully to provide source specific tracers for studying the chemistry and dispersion of ambient aerosols and the intermingling of natural with anthropogenic emissions and with smoke plumes. A brief review of the organic matter composition in aerosols derived from the major sources is also given, with emphasis on the detection of biomass burning components. These major sources are the natural background from biogenic detritus (e.g. plant wax, microbes, etc.) and anthropogenic particle emissions (e.g. oils, soot, synthetics, compounds, etc.). The emissions of organic constituents in coal smoke particulate matter are also reviewed and depend on combustion temperature, ventilation, burn time, and coal rank (geologic maturity). The components of peat and brown coal and to a lesser degree semi-bituminous coal consist mainly of hydrocarbons, biomarkers, and aromatic components, quite similar to burning of contemporary biomass. Dispersion from the source and long range transport of smoke particulate matter with the associated organic compounds is also discussed.     

Geochemical constraints on chemolithoautotrophic metabolism by microorganisms in seafloor hydrothermal systems

Mixing of hydrothermal fluids and seawater at the ocean floor, combined with slow reaction kinetics for oxidation/reduction reactions, provides a source of metabolic energy for chemolithotrophic microorganisms which are the primary biomass producers for an extensive submarine ecosystem that is essentially independent of photosynthesis. Thermodynamic models are used to explore geochemical constraints on the amount of metabolic energy potentially available from chemosynthetic reactions involving S, C, Fe, and Mn compounds during mixing of hydrothermal fluids with seawater. For the vent fluid used in the calculations (EPR 21 degrees N OBS), the model indicates that mixing environments are favorable for oxidation of H2S, CH4, Fe2+ and Mn2+ only below approximately 38 degrees C, with methanogenesis and reduction of sulfate or S degrees favored at higher temperatures, suggesting that environments dominated by mixing provide habitats for mesophilic (but not thermophilic) aerobes and thermophilic (but not mesophilic) anaerobes. A maximum of approximately 760 cal per kilogram vent fluid is available from sulfide oxidation while between 8 and 35 cal/kg vent fluid is available from methanotrophy, methanogenesis, oxidation of Fe or Mn, or sulfate reduction. The total potential for chemosynthetic primary production at deep-sea hydrothermal vents globally is estimated to be about 10(13) g biomass per year, which represents approximately 0.02% of the global primary production by photosynthesis in the oceans. Thermophilic methanogens and sulfate- and S degree-reducers are likely to be the predominant organisms in the walls of vent chimneys and in the diffuse mixing zones beneath warm vents, where biological processes may contribute to the high methane concentrations of vent fluids and heavy 34S/32S ratios of vent sulfide minerals. The metabolic processes taking place in these systems may be analogs of the first living systems to evolve on the Earth.     

加热时间对生烃模拟过程的影响

通过 36 0℃、不同模拟时间下生油岩生烃演化过程的分析 ,探讨了加热时间对模拟结果的影响。发现延长加热时间 ,气体产率将不断增加 ,其中总烃气增加幅度大于非烃气体。同时丁烷、戊烷和 C+ 5烃类含量在时间很长时发生裂解生成更小分子的甲烷、乙烷和丙烷。随模拟时间的延长 ,非烃气中除氢气含量随加热时间延长而增加外 ,其余非烃气包括二氧化碳、氮气、氧气和一氧化碳等气体和液态产物产率降低 ,干酪根元素组成中 x( H) /x( C)值和 x( O) /x( C)值不断降低 ,而镜质体反射率变化不明显。     

Chemical structural models for coalified wood (vitrinite) in low rank coal

Examination of a series of coalified gymnospermous woods ranging in rank from brown coal to subbituminous coal by solid-state ¹³C NMR and analytical pyrolysis has provided sufficient information to construct structural models depicting the changes that occur to lignin, the primary precursor of vitrinite, during coalification. Progressive changes in the chemistry of coalified wood suggest the following series of reactions: (1) demethylation to form catechol-like structures that are dominant components of brown coal and lignite A; (2) cleavage of aryl ether linkages to form phenols and reactive carbocations that alkylate the catechol rings; (3) dehydration of the catechol rings; (3) dehydration of the catechol-like structures to form the structures of subbituminous coal dominated by alkylphenols; and (4) reduction of the 3-carbon alkyl side chain derived from lignin to form propyl substituents. The models developed for each stage of coalification are derived from chemical modifications of the structure of lignin.