采用热重分析(TGA)和热解-气相色谱/质谱(Py-GC/MS)联用技术对 6个不同成熟度煤的热解过程及热解产物进行表征.TGA 结果表明,不同成熟度煤的失重(TG)曲线具有相似性且在失重速率(DTG)曲线中有3 个明显的失重速率峰;随着成熟度的增加,煤在最高热解温度时的总失重率(wt)减小,最大失重速率(-(dw/dt)max)降低,但最大失重速率峰温度(Tmax)升高,说明低成熟度煤中热不稳定结构的含量较高.Py-GC/MS结果表明,不同成熟度煤的热解产物均以芳香类化合物为主(47.4%～94.7%),且芳香类热解产物的含量随成熟度的增加逐渐升高,说明高成熟度煤热解过程中产生的芳香类化合物较多,而热解产物中酚类、呋喃类和脂肪烃类化合物的占比随煤样成熟度的增加逐渐降低,表明低成熟度煤在热解过程中释放出高含量的极性含氧化合物.研究结果对进一步了解煤炭资源的规模化开发和合理利用具有重要意义.

Biomass burning (BB) and coal combustion (CC) are important sources of brown carbon (BrC) in ambient aerosols. In this study, six biomass materials and five types of coal were combusted to generate fine smoke particles. The BrC fractions, including water-soluble organic carbon (WSOC), humic-like substance carbon (HULIS-C), and methanol-soluble organic carbon (MSOC), were subsequently fractionated, and their optical properties and chemical structures were then comprehensively investigated using UV–visible spectroscopy, proton nuclear magnetic resonance spectroscopy (1H NMR), and fluorescence excitation–emission matrix (EEM) spectroscopy combined with parallel factor (PARAFAC) analysis. In addition, the oxidative potential (OP) of BB and CC BrC was measured with the dithiothreitol (DTT) method. The results showed that WSOC, HULIS-C, and MSOC accounted for 2.3 %–22 %, 0.5 %–10 %, and 6.4 %–73 % of the total mass of combustion-derived smoke PM2.5, respectively, with MSOC extracting the highest concentrations of organic compounds. The MSOC fractions had the highest light absorption capacity (mass absorption efficiency at 365 nm (MAE365): 1.0–2.7 m2/gC) for both BB and CC smoke, indicating that MSOC contained more of the strong light-absorbing components. Therefore, MSOC may represent the total BrC better than the water-soluble fractions. Some significant differences were observed between the BrC fractions emitted from BB and CC with more water-soluble BrC fractions with higher MAE365 and lower absorption Ångström exponent values detected in smoke emitted from BB than from CC. EEM-PARAFAC identified four fluorophores: two protein-like, one humic-like, and one polyphenol-like fluorophores. The protein-like substances were the dominant components of WSOC (47 %–80 %), HULIS-C (44 %–87 %), and MSOC (42 %–70 %). The 1H-NMR results suggested that BB BrC contained more oxygenated aliphatic functional groups (H-C-O), whereas CC BrC contained more unsaturated fractions (H-C-C= and Ar−H). The DTT assays indicated that BB BrC generally had a stronger oxidative potential (DTTm, 2.6–85 pmol/min/µg) than CC BrC (DTTm, 0.4–11 pmol/min/µg), with MSOC having a stronger OP than WSOC and HULIS-C. In addition, HULIS-C contributed more than half of the DTT activity of WSOC (63.1 % ± 15.5 %), highlighting that HULIS was a major contributor of reactive oxygen species (ROS) production in WSOC. Furthermore, the principal component analysis and Pearson correlation coefficients indicated that highly oxygenated humic-like fluorophore C4 may be the important DTT active substances in BrC.

The pyrobitumen in conventional petroleum reservoirs is a thermally altered product of ancient oil pools, which may provide valuable source information using its molecular and isotopic signatures. Pyrobitumen formation is often associated with thermal alteration of asphaltene or polar-rich components rather than that of oil as a whole. Although asphaltenes are useful in source correlation of altered oils, the geochemical characteristics of asphaltene-derived pyrobitumen are poorly understood. In this study, artificial pyrobitumen formation through oil asphaltene cracking was performed at different thermal simulation (i.e., pyrolysis) temperatures. Systematic variations in the amounts and distributions of extractable and bound hydrocarbons, released by catalytic hydropyrolysis of the artificially produced pyrobitumen were studied. Pyrobitumen production yield was high at pyrolysis temperatures corresponding to post oil peak maturities, with a maximum yield of similar to 70 wt% of asphaltene being reached in the early condensate-wetgas stage. The molecular structure of pyrobitumen varied only slightly over the high maturity range (EasyRo 1.64-2.51%). Compared with the parent asphaltene, the pyrobitumen had a low biomarker (e.g., regular steranes and terpanes) content, and even the carbon isotopic values of the more stable bound n-alkanes were strongly altered. Thermal cracking of asphaltene alone, rather than whole oil, accelerates cross-linking of aromatic units, and cleavage or condensation of molecules bound in the pyrobitumen. These molecular changes suggest that care is needed when using the geochemical characteristics of bound hydrocarbons in natural pyrobitumen for source determinations. Nevertheless, the carbon isotopic ratios of bulk pyrobitumen hydropyrolysate were similar to those of bulk oil or pyrobitumen, even at very high maturities, suggesting these may be reliable indices for source tracing. A comparison of carbon isotopic compositions between pyrobitumen-bound and solvent-extractable n-alkanes could be useful in determining whether they have the same origin. Furthermore, the compositional and isotopic characteristics of bound hydrocarbons in pyrobitumen may provide information on the stage of maturity under geological conditions. The investigation of free and bound molecules may thus elucidate pyrobitumen genesis as related to its source, thermal maturity, and possible later hydrocarbon charging. (C) 2020 Elsevier Ltd. All rights reserved.

Organic matter (OM) compositions greatly affect hydrocarbon generation and expulsion processes, which are critical for the organic porosity development in shale. Lacustrine shale samples of low thermal maturity were pyrolyzed using two pyrolysis systems (closed and semi-closed systems). Pore development was measured by low-pressure gas adsorption and field emission-scanning electron microscopy (FE-SEM), and bulk porosity was modeled utilizing organic geochemical data. The gas adsorption analysis indicated that shale samples of different OM compositions differed in pore volume evolution with thermal maturity, mainly related to the different amounts of hydrocarbon generated and expelled. Residual bitumen significantly reduced the pore volume of OM-rich oil generative shale samples, and restricted the micro-, meso-, and macro-pore volumes to different extents. Calculations and experiments both showed that OM-rich and oil generative shale experienced a greater increase in pore volume after the oil peak. In addition, it was observed that variations in the main pore types were associated both with shale compositions and with exerted overburden pressure. Increase in overburden pressure were found to greatly facilitate the development of nanometer-size spongy and complex OM pores in shales containing type Ⅱ/Ⅲ kerogens, possibly as a result of the expulsion of gaseous hydrocarbons. By contrast, the shale with abundant type Ⅰ kerogen tended mainly to develop relatively large pores following oil expulsion regardless of overburden pressure. The modeled organic porosity of pyrolyzed samples of type III OM was similar to the porosity of geological shale, but the porosity of OM-rich oil generative shale samples with high expulsion efficiency at the oil generation stage was two to three times the measured porosity of the geological shale. In some cases, the higher modeled shale porosity might be related to the higher expulsion efficiency. For geological shales of expulsion efficiency comparable to the pyrolyzed samples, geological processes (e.g., compaction and cementation) may have greatly reduced the OM-associated pore volume.

Humic-like substances (HULIS) constitute a significant fraction of the water-soluble organic compounds in the environment and influence many properties of atmospheric aerosols. In this study, three solid phase extraction (SPE) methods that involve the use of hydrophilic/lipophilic balanced (HLB) resin with pure methanol (HLB-M), HLB resin with 2% (v/v) ammonia/methanol (HLB-N), and Bond Elut PPL (Priority PolLutant) resin with methanol (PPL), were compared for the isolation of HULIS from atmospheric aerosols. The HLB-N and PPL methods efficiently recovered Suwannee River fulvic acid (SRFA) and were excellent for quantifying HULIS at low levels in aerosols. All three SPE methods were favorable for the elution of aromatic and strongly UV-absorbing compounds. However, the chemical structures and molecular compositions of the HULIS isolated by the three methods showed some differences. The HULISHLB-N and HULISPPL fractions contained higher concentrations of aliphatic and aromatic C–H groups than did the HULISHLB-M fraction, indicating that relative higher content of weak polar organic species in HULIS fractions isolated by the HLB-N and PPL methods than those isolated by the HLB-M method. Moreover, the HULISHLB-N and HULISPPL were both characterized by having lower relative abundance-weighted modified aromaticity index values and higher concentrations of S-containing compounds than the HULISHLB-M, as indicated by Fourier transform ion cyclotron resonance mass spectrometry. Some N-containing structures were identified only in the HULISHLB-N, suggesting that some of HULIS molecules were changed during the HLB-N treatment. Based on these comparisons of the three methods, we found that the PPL method serves equally good as compared to other two methods, and therefore, one can utilize PPL method also for HULIS isolation and characterization.

Light and condensable oils derived from mature kerogen and residual oil in deep source rocks have contributed strongly to a rapid increase in oil production. In this study, oil expulsion from kerogen and shale was simulated by selective solvent extraction (hexane/toluene, 9:1 v/v, instead of the commonly used dichloromethane) and by returning the extracts (so-called "oil a") back into a controlled mass of mature kerogen. The maturity intervals and potential of the light oil and condensates were investigated by analyzing the yields of different hydrocarbons from the subsequent pyrolysis of mature kerogen-"oil a" mixtures. The gas-to-oil ratio was used to constrain the maturity range for the light oil, condensate, and gas stages. The lowest equivalent vitrinite reflectance (EVRo, 1.9-2.1%) for the gas stage was compatible with commonly accepted models. The EVRo cutoff of 1.55-1.75% between light oil and condensate was higher than that in traditional models, although this depended primarily on the generality of the "condensate" definition. An EVRo ranging between 1.35 and 1.55-1.75% was defined in this work as the "light oil/gas" substage within the commonly accepted condensate/wet gas stage. Moreover, yields of hydrocarbons from the cracking of "oil a" were distinctly affected by mature kerogen. This effect showed little difference on the yield of C6-14 hydrocarbons and C15+ hydrocarbons but notable difference for the gases between types I and II kerogens. The release of C6-14 hydrocarbons was promoted when the release of C15+ hydrocarbons was notably inhibited. Approximately linear relationships were established between maximum yields of liquid hydrocarbons and the carbon content of "oil a" (selective solvent extraction products) in the mixtures. This relationship was helpful in estimating both oil and total petroleum potential of deep source rocks that have undergone oil generation and expulsion, but it was dependent on the composition of the solvents used in extraction.

Dichlorodiphenyltrichloroethane (DDT) is well known for its harmful effects and has been banned around the world. However, DDT is still frequently detected in natural environments, particularly in aquaculture and harbor sediments. In this study, 15 surface sediment samples were collected from a typical tropical bay (Zhanjiang Bay) in the South China Sea, and the levels of DDT and its metabolites in sediment and porewater samples were investigated. The results showed that concentrations of DDXs (i.e., DDT and its metabolites) in bulk sediments were 1.58-51.0 ng g(-1) (mean, 11.5 ng g(-1)). DDTs (DDT and its primary metabolites, dichlorodiphenyldichloroethane (DDD) and dichlorodiphenyldichloroethylene (DDE)) were the most prominent, accounting for 73.2%-98.3% (86.1% +/- 12.8%) of the DDXs. Additionally, high-order metabolites (i.e., 1-chloro-2,2-bis(4'-chlorophenyl)ethylene (p,p'-DDMU), 2,2-bis(p-chlorophenyl)ethylene (p,p'-DDNU), 2,2-bis(p-chlorophenyl)ethanol (p,p'-DDOH), 2,2-bis(p-chlorophenyl) methane (p,p'-DDM), and 4,4'-dichlorobenzophenone (p,p'-DBP)) were also detected in most of the sediment and porewater samples, with DDMU and DBP being predominant. The DDTs concentration differed among the sampling sites, with relatively high DDTs concentrations in the samples from the aquaculture zone and an area near the shipping channel and the Haibin shipyard. The DDD/DDE ratios indicated a reductive dichlorination of DDT to DDD under anaerobic conditions at most of the sampling sites of Zhanjiang Bay. The possible DDT degradation pathway in the surface sediments of Zhanjiang Bay was p,p'-DDT/p,p'-DDD(p,p'-DDE)/p,p'-DDMU/p,p'-DDNU/. /p,p'-DBP. The DDXs in the sediments of Zhanjiang Bay were mainly introduced via mixed sources of industrial DDT and dicofol, including fresh input and historical residue. The concentrations of DDXs in porewater samples varied from 66.3 to 250 ng L--1,L- exhibiting a distribution similar to that in the accompanying sediments. However, the content of high-order metabolites was relatively lower in porewater than in sediment, indicating that high-order degradation mainly occurs in particles. Overall, this study helps in understanding the distribution, source, and degradation of DDT in a typical tropical bay. (c) 2020 Elsevier Ltd. All rights reserved.

近年来塔里木盆地的深层油气勘探取得突破,有必要对寒武系高-过成熟烃源岩的有机质碳同位素组成进行深入研究,已有工作对干酪根催化热解产物中正构烷烃碳同位素组成的关注不多.本文对来自塔里木盆地内钻井和西缘露头的8个寒武系烃源岩干酪根进行了催化加氢热解实验.结果表明,氢解产物无论碳数分布还是分子碳同位素组成特征都表现出较大的变化.盆地内钻井烃源岩干酪根催化加氢热解产物中低碳数正构烷烃(C14～C20)具有明显的偶碳优势,部分样品C22正构烷烃优势明显;而柯坪地区露头样品干酪根催化加氢热解产物中正构烷烃不具有或具有微弱的偶碳数优势.钻井和柯坪露头烃源岩干酪根催化加氢热解产物中正构烷烃的碳同位素组成均随碳数增加逐渐变轻,低碳数正构烷烃(C14～C20)碳同位素组成没有明显偶碳数偏重的分布特征.此外,柯坪露头烃源岩正构烷烃的碳同位素组成(-34.5‰ ～-31.5‰)明显比盆地内钻井烃源岩中的正构烷烃(-32.3‰ ～-26.4‰)偏轻,这一变化与干酪根总碳同位素组成的变化一致.正构烷烃及其碳同位素分布特征的差异可能主要反映了烃源岩沉积时期,分层水体导致有机质母源或沉积环境的变化.除了寒武、奥陶系烃源岩有机质碳同位素组成上的差异,如何利用同位素手段对中-下寒武统烃源岩自身变化进行油源判识,也是亟需考虑的问题.

本文主要利用热解-气相色谱质谱联用技术(Py-GC/MS)对珠三角典型区域的大气颗粒物的化学特征进行研究,讨论了不同地区样品的化学和来源组成.结果 显示,不同样品热解产物的组成具有一定的类似性.这些化合物均以脂肪烃(24.6％ ～ 52.2％)、脂肪酸(5.0％～43.6％)、芳香化合物(14.7％ ～ 36.3％)为主,另外还包括苯酚类化合物(0.68％～11.5％)、呋喃类化合物(0.26％ ～ 5.86％)、含N化合物(4.80％～ 10.2％)和含S化合物(NA～0.67％)等,表明这些样品主要由芳香碳和脂肪链结构组成,连接有含氧、氮等杂原子基团.同时不同地区的气溶胶样品的热解产物也具有一定的差异性,反映了气溶胶中有机质的组成、来源是有差异的,如从化样品中植物来源贡献是最多的,其次是珠海,广州最少.另外不同季节采集的气溶胶样品的热解产物也表现出一定的差异性,一般情况下夏季样品中生物质来源贡献更多,而冬季样品中则是老化的气溶胶更多.

主要利用热解-气相色谱/质谱联用技术(Py-GC/MS)对不同成熟度的家用蜂窝煤燃烧排放烟炱(soot)颗粒的化学特征进行研究,并探讨了成熟度对燃煤排放soot颗粒热解产物的影响.结果显示:不同成熟度的燃煤排放soot颗粒热解产生类似的产物.这些化合物均以芳香化合物(58.1％～92.0％)为主,另外还含有酚类化合物(0.66％～32.3％)、脂肪烃(0.21％～9.57％)、呋喃类化合物(1.42％～2.57％)、含硫化合物(NA～4.12％)和含氮化合物(NA～3.91％)等,表明不同成熟度蜂窝煤燃烧排放的soot颗粒都是以高度芳香性的结构为核心,连接有含氧、氮等杂原子基团组成.研究结果还显示,原煤成熟度对soot颗粒的热解特征具有一定的影响.总体上,soot颗粒热解产物中芳香化合物的百分含量随着煤样成熟度的增加呈现递增趋势,而酚类化合物的百分含量则随着煤样成熟度的增加逐渐降低,另外含氮化合物主要存在于低成熟度煤样燃烧排放的soot颗粒样品中.本文研究结果表明了随着煤成熟度的升高,燃烧排放的soot颗粒的芳香性逐渐增强,含O、N等不稳定结构逐渐减少.含硫化合物是燃煤排放soot颗粒的特征化合物,主要存在于高成熟度燃煤排放的soot颗粒中.这些结果对于了解不同成熟度的燃煤排放soot颗粒样品中分子结构和组成具有重要的意义.

Sixteen surface sediment samples were collected from the estuary of the Suixi river to the mouth of Zhanjiang Bay and then analyzed for organochlorine pesticides (OCPs) by GC-MS to investigate their distribution and ecological risk. The results showed that the concentrations of OCPs in the sediments ranged from nd to 189.52 ng·g-1 (mean 32.17 ng·g-1), including HCHs (mean 5.81 ng·g-1) and DDTs (mean 26.90 ng·g-1). The distribution characteristics showed that the highest OCPs concentrations were found in the estuary and the main shipping lane areas, and the concentration in the nearshore area was higher than that offshore. Source analysis indicated that the HCHs mainly originated from agricultural applications, while no industrial input was observed. Some "hot-spots" areas occurred in harbors and shipping channels, likely as a result of the presence of paint flakes. Additionally, the concentrations of DDTs were found to be higher than the limits of Chinese Marine sediment quality criteria, and p,p'-DDT was the main type of DDT, presenting inevitable adverse biological effects and high ecological risk. Compared with other bays in China, the concentrations of OCPs in this study were in the upper-median pollution level, especially in harbors and boat maintenance facility areas. High OCPs inputs may occur, and thereby represent a certain ecological risk in Zhanjiang Bay.

本论文主要利用热解-气相色谱/质谱联用仪(Py-GC/MS)对不同温度制备生物炭的化学特征进行了研究,并探讨了制备温度对生物炭热解产物的影响.结果显示,不同温度制备的稻秆(RS)、玉米秆(CS)和松木(PW)生物炭的热解产物组成具有一定类似性.这些化合物均以芳烃和苯酚类化合物为主(55％～100％),另外还包含有呋喃类化合物(NA～31％)以及少量含氮化合物(NA～1.7％)等杂原子化合物,表明不同类型的生物炭具有较为类似的化学结构,均以芳香性结构组分以及连接在芳香结构上的烷基或含氧、氮等杂原子基团组成.然而不同温度制备生物炭的热解产物,其相对含量具有明显的差异.低温制备(≤350℃)的生物炭热解产物中检出较高含量的酚类化合物、呋喃类化合物和含氮化合物等,意味着生物炭中还保留了部分半纤维素、纤维素和木质素组织.随着制备温度的升高,热解产物中含氧、氮等杂原子的不稳定结构逐渐减少,相反,芳烃化合物的相对含量逐渐增加,表明生物炭逐步向缩合程度高的芳香化结构转变.此外,在相同制备温度条件下,3类生物炭的热解产物中可鉴定化合物的数量大小顺序为:RS>PW>CS.脂肪烃类化合物仅在RS中检出,而含硫化合物仅在PW中检出.这些结果表明,制备温度和原料均对生物炭的化学特征具有明显的影响,这对于生物炭的制备和应用等具有参考意义.

Shale oil and tight oil are current hot spots of oil and gas exploration,and the shale hydrocarbon-generating simulation experiment can provide important information for the exploration of these oil and gas resources.Taking the shale in 7th Member of Yanchang Formation (Chang-7 Member),Ordos Basin,the gold tube-autoclave hydrocarbon-generating simulator is used to systematically study the Type-Ⅱ organic matter,the gaseous hydrocarbon (C1 5),light hydrocarbon (C6-14),heavy hydrocarbon (C14+),other components of hydrocarbon-generating products in the maturity range (Easy Ro 0.7％-1.6％) corresponding to "oil-generation window",and the geochemical characteristics of hydrocarbon generation residues.It is found that in the shale of Chang-7 Member during oil-generation period,gaseous hydrocarbons of 2.35-103.91 mL/g and light hydrocarbons of 10.83-88.24 mg/g are produced simultaneously.The peak yield of heavy hydrocarbons corresponds to Easy Ro of 1.00％,closely approaching to the maturities corresponding to the peak yield of saturated hydrocarbons,aromatics and non-hydrocarbons.Moreover,theasphaltene yield of heavy hydrocarbons starts to decline after reaching the Easy Ro of 1.35％,reflecting subsequent large scale of asphahene cracking and solidification.However,the light/heavy ratio (gaseous hydrocarbon/light hydrocarbon) and gas/oil ratio (light hydrocarbon/heavy hydrocarbon) vital for physical property of crude oil are continuously increasing as the maturity getting higher,and the increasing rates are evidently accelerated after Easy Ro of 1.05％-1.15％.During oil-generating process,the massive loss of HI and H element of shale residue and the kerogen solid carbon isotope becoming heavier occur prior to Easy Ro of 1.00％;the kerogen solid carbon isotope changes less,and can be taken as an original source index in Ordos Basin.Through comparing six kinds of common biomarker maturity parameters in the hydrocarbon-generating products,it is validated that MPI and F1 among the PAH maturity are linearly correlated to maturity in the whole oil-generating window,and can be used to identify the crude oil maturity in the shale of Chang-7 Member in Ordos Basin.The change nodes of various geochemical characteristics of hydrocarbon-generating products and the maturity indexes can be applied to the exploitability assessment for shale oil or correlative tight oil in 7th Member of Yanchang Formation,Ordos Basin.

Fast pyrolysis is one of the most promising methods to convert lignin into fuels and chemicals. In the present study, pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) was used to evaluate vapor phase product distribution of lignin fast pyrolysis. During the non-catalytic pyrolysis process, lignin was pyrolyzed at 400 degrees C, 500 degrees C and 600 degrees C respectively, finding that the highest yield of aromatic hydrocarbons was obtained at 600 degrees C. Catalytic pyrolysis experiments were also conducted to investigate the effects of catalyst pore structure and acidity on the product distributions. Five different catalysts (HZSM-5, MCM-41, TiO2, ZrO2 and Mg(Al) O) were applied to lignin catalytic pyrolysis, and the catalytic performance was estimated by analyzing the pyrolytic products. The catalysts were characterized by using X-ray diffraction ( XRD), BET, and NH3 (CO2) temperature programmed desorption. Based on these characterizations, discussion was carried out to explain the formation of the produc distributions. Among the five catalysts, HZSM-5 exhibited the best performance on the formation of aromatic hydrocarbons.

Black carbon (BC) was divided into soot and charcoal based on the formation processes.In this study,four representative feedstocks including masson pine,rice straw,corn straw and coal were collected to produce soot-and charcoal-BC materials.Then,these BC materials were characterized by elemental analysis and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS).The results showed that the elemental compositions of different types of BC materials are very similar,with the highest content of carbon,followed by oxygen,hydrogen and nitrogen.However,each BC sample has its distinct properties.The atomic ratios of H/C,O/C,N/C and (O+N)/C were higher for soot samples than charcoal samples formed from the same feedstock,indicating relatively high contents of polar components in soot samples.Py-GC/MS results revealed that the pyrolysis products derived from different BC samples were generally similar,including aromatic compounds,N-containing compounds,furan compounds,phenolic compounds and S-containing compounds.They were all dominated by aromatic compounds,indicating these BC materials were characterized by having aromatic nuclei and linear or branched aliphatic chains,and/or oxygen-,nitrogen -containing units.However,some differences were also observed among these BC materials.The pyrolysis products revealed that biomass soots contain more useful information on original biomass materials such as proteins,lignins and polysaccharides,while charcoals contain higher contents of condensed aromatic structures.The results may be useful for understanding the compositions and molecular structures of different types of BC materials.

The extraction procedure using solvent mixtures has been used to elute n-alkanes adsorped by 5(A) molecular sieve and subsequent stable carbon isotope ratio analysis of individual n-alkanes.However, a 5(A) molecular sieve may catalyze the hydrogen exchange of organic molecules during long-term heating.Therefore, the usage of this method for hydrogen isotopic analysis needs to be evaluated.Two different types of crude oil saturated hydrocarbon and n-alkanes mixed standard samples were used as the object for this study.The extraction method using cyclohexane and n-heptane solvent mixtures and another method evolving the digestion with hydrofluoric-acid and solvent extraction were both used to elute adsorbed n-alkanes by the 5(A) molecular sieve.The separation efficiency of the two methods was compared, and both carbon and hydrogen isotopes of obtained n-alkanes have been analyzed.Results show that the two methods enable excellent separations of n-alkanes, and yield variations of the hydrogen isotope ratios smaller than 4‰, within uncertainty.The average recovery of n-alkanes obtained by three-time solvent extraction was 58%, whereas that obtained by hydrofluoric acid dissolution and solvent extraction was 68%.Although cyclohexane and n-heptane solvent mixture has lower extraction efficiency and involves multiple heating processes, these two factors do not result in significant fractionation or exchange of hydrogen isotopes, indicating that this method can be applied to the separation and purifying of n-alkanes and subsequent compound-specific hydrogen isotopic analysis.

The Ediacaran period was critical in the evolution of the biosphere and ocean in the history of the Earth. Shales rich in organic matter (OM) are well developed for this period in the Yangtze Block, China, and have recently been related to shale gas exploration in South China. To date, detailed characterisation of the Ediacaran shales is not available. The present work sets out a detailed investigation of the composition and pore characteristics of samples from a shallow drill core in the Ediacaran Lantian Formation in the Lower Yangtze area, and the effects of shale composition on the pore growth are discussed.The 90-m-thick Lantian black shales are highly over-mature (equivalent vitrinite reflectance (EVRo) value approximately 4.0%) with a total organic carbon (TOC) content up to 12%. They are dominated by quartz (33–72%), generally with low clay or feldspar content (<20%) and highly varied carbonate content (up to 60%). The Lantian shales are also notable for their high pyrite content (up to 19%), suggesting a depositional environment of an anoxic water body rich in sulphates; greatly enriched OM is facilitated in deep-water environments.Bulk porosities of the shales range from 1.0% to 7.9%, and are positively correlated with TOC content. High-magnification scanning electron microscopy (SEM) images support the crucial importance of OM content on pore development. Generally, pore volume shows excellent, positive correlation with TOC content for micropores, good correlation for mesopores, and relatively poor correlation for macropores. Two samples with mostly high TOC content showed very low macropore volume and medium mesopore volume. These results suggest a close relationship between OM with relatively small pores, and enhanced compaction effect on large pores in highly OM-enriched shales.

Yecheng depression in Tarim Basin developed several layers of source rocks, including Carboniferous Kalawuyi formation, Permian Qipan formation and Pusige formation 2-3 parts, Jurassic Yarkant formation and coal measure strata. These source rocks may be the origin of condensates from Well Kedong 1 and crude oil from Kekeya Tertiary strata. The origin of crude oil in this area has been controversial for a long time. We selected 2 condensate samples from Well Kedong 1,7 Tertiary crude oil samples from Keliyang tectonic belt of Yecheng depression, 17 representative source rock samples, and finished a series of measuring-analysis work on geochemistry parameters of these samples, such as biomarkers and individual hydrocarbon isotopic composition ratio. Oil-oil correlation shows that condensates from Well Kedong 1 and Kekeya Tertiary strata have much in common in n-alkanes component, maturity and stable carbon isotope, indicating their same-origin characteristics. Oil-source correlation shows that source rocks from underpart of 2-3 sections of Pusige formation may be origin of crude oil in the research area. Pusige formation source rock strata and crude oil from Kekeya area have the same maturity and similar characteristic biomarkers, that is high content of C30 rearrangement hopane, Ts, C27-C29 diasteranes, etc, while other source rocks strata don’t have this feature. The crude oil’s high maturity may explain&nbsp;why there is a 2‰-3‰ difference in stable carbon isotope ratio between condensates from Well Kedong 1 and soluble organic matters from Pusige formation 2-3 section’s underpart source rocks.

Formation water is often accompanied with oils and gases in the Lunnan Oilfield,Tarim Basin,while reservoirs with different kinds of caprocks show apparent variations in characters and distributions of formation water.In the study area,reservoirs in the Lungu 7 and 2 Lungu blocks have little Upper Ordovician deposits due to the adjacence to upheaval and severe denudation,while Middle Ordovician reservoirs in the eastern Lungu block are overlain with multiple suites of Upper Ordovician carbonates.Therefore,they are characterized by a weathering-crust reservoir and deeply-buried reservoir,respectively,and have different formation water that varies regularly with the increase of the burial depth and overlying caprock thickness of reservoirs.Comparatively,formation water in the weathering-crust reservoir shows higher salinity,chlorine content,Cl/Br ratio and 87Sr/86Sr ratio,but lighter δ18O and δD values than that in the deeply-buried reservoir.These variations of formation water in different reservoirs are probably attributed to the dissolution,admixture and water-rock interaction of formation water,which result from different kinds of reservoirs,particularly the difference in caprock thickness.

The methods of traditional petroleum geochemical evaluation in accordance with the organic matter abundance,its type and maturity could not meet the demands of chemical and biological causation of early micro-organisms,which was the key element for low maturity biogas exploration.Therefore,it needed to re-establish a biogas source rock evaluation system.Starting from the early headstream of biogas,based on the protein content of biological macromolecules,nitrogen isotopes and C/N ratio,the characteristics of biogas sedimentary organic matter were analyzed in combination with traditional rock pyrolysis data.Through analysis of the production gas wells,the δ15N,protein content and the traditional geochemical indicators are corresponding to the major gas producing intervals,δ15N can reflect the characteristics of biogas maternal environment,the protein content of biological macromolecules can be characterized the abundance of the microbial nutrient and the degree of the intensity of microbial activity.Therefore δ15N and the protein content combined with the traditional geochemical indicators can be used to evaluate the biogas source rocks.