山东济宁许厂煤矿下组煤瓦斯与二氧化碳开发利用前景及存在的问题

许厂煤矿下组煤中蕴藏着较为丰富的瓦斯、二氧化碳资源。下组煤位于瓦斯风化带内,含瓦斯、二氧化碳和氮气等气体,瓦斯含量与埋藏深度呈正相关关系,主要存在低含量瓦斯、二氧化碳抽采率、二氧化碳资源化转换等技术方面的问题。从国家相关优惠政策、资源优势、煤与煤层气一体化开发技术、近水平长钻孔定向钻进技术、煤层压裂造缝技术、煤层注气增产技术和瓦斯、二氧化碳气体提纯技术等关键技术的发展程度,结合煤矿的下组煤层的开采方案,认为许厂煤矿有着较好的煤炭与瓦斯、二氧化碳一体化开发利用前景。     

Comparative Study of Hydrogen and Carbon Isotopic Composition of Gases Generated from the Pyrolysis of a Peat under Saltwater and Freshwater Conditions

To understand the influence of the diagenetic water medium on the isotopic compositions of thermogenic coalbed gas, both hydrous and anhydrous closed-system pyrolyses were performed at temperatures of 250°C to 650°C on an herbaceous marsh peat. Compared to the results of anhydrous pyrolysis, the hydrocarbon gases generated from hydrous pyrolyses have very different hydrogen isotopic compositions. However, the carbon isotopic compositions of the hydrocarbon gases became only slightly heavier in hydrous pyrolysis, compared to that from anhydrous pyrolysis. With the progress of thermal evolution from peat to a more advanced thermal maturity of vitrinite reflectance values (Ro) of 5.5% during the pyrolysis, the difference in the average δD value increased from 52‰ to 64‰ between the hydrous pyrolysis with saltwater and anhydrous pyrolysis and increased from 18‰ to 29‰ between the hydrous pyrolysis with freshwater and anhydrous pyrolysis, respectively. The difference in the average δ13C value was only 1‰–2‰ between the hydrous and anhydrous pyrolysis. The relationships between the δD values of the generated hydrocarbon gases and Ro values as well as among δD values of the hydrocarbon gas species are established. The close relationships among these parameters suggest that the water medium had a significant effect on the hydrogen isotopic composition and a minimal effect on the carbon isotopic composition of the hydrocarbon gases. The results of these pyrolyses may provide information for the understanding of the genesis of coalbed gas from herbaceous marsh material with the participation of different diagenetic water media.     

发射光谱法测定区域化探样品中的Pb、Sn、Mo、V元素

采用发射光谱法测定区域化探样品中Pb、Sn、Mo、V元素,以焦硫酸钾、氟化钠、三氧化二铝和碳粉的混合物为固体缓冲剂,采用外加内标法以锗（Ge）作为内标元素,选择合适的分析线对,选取国家一级地球化学标准物质（GBW水系沉积物、土壤）平行测定（n=12次）.测试结果准确度达到规范要求,满足区域化探样品的检测要求.     

The source of sulfur in sulfide deposits in the Siberian Platform traps (from isotope data)

The source of sulfur in giant Norilsk-type sulfide deposits is discussed. A review of the state of the problem and a critical analysis of existing hypotheses are made. The distribution of δ³⁴S in sulfides of ore occurrences and small and large deposits and in normal sedimentary, metamorphogenic, and hypogene sulfates is considered. A large number of new δ³⁴S data for sulfides and sulfates in various deposits, volcanic and terrigenous rocks, coals, graphites, and metasomatites are presented. The main attention is focused on the objects of the Norilsk and Kureika ore districts. The δ³⁴S value varies from -14 to + 22.5‰ in sulfides of rocks and ores and from 15.3 to 33‰ in anhydrites. In sulfide-sulfate intergrowths and assemblages, δ³⁴S is within 4.2-14.6‰ in sulfides and within 15.3-21.3‰ in anhydrites. The most isotopically heavy sulfur was found in pyrrhotite veins in basalts (δ³⁴S = 21.6‰), in sulfate veins cutting dolomites (δ³⁴S = 33‰), and in subsidence caldera sulfates in basalts (δ³⁴S = 23.2-25.2‰). Sulfide ores of the Tsentral’naya Shilki intrusion have a heavy sulfur isotope composition (δ³⁴S = + 17.7‰ (n = 15)). Thermobarogeochemical studies of anhydrites have revealed inclusions of different types with homogenization temperatures ranging from 685 °C to 80 °C. Metamorphogenic and hypogene anhydrites are associated with a carbonaceous substance, and hypogene anhydrites have inclusions of chloride-containing salt melts. We assume that sulfur in the trap sulfide deposits was introduced with sulfates of sedimentary rocks (δ³⁴S = 22-24‰). No assimilation of sulfates by basaltic melt took place. The sedimentary anhydrites were “steamed” by hydrocarbons, which led to sulfate reduction and δ³⁴S fractionation. As a result, isotopically light sulfur accumulated in sulfides and hydrogen sulfide, isotopically heavy sulfur was removed by aqueous calcium sulfate solution, and “residual” metamorphogenic anhydrite acquired a lighter sulfur isotope composition as compared with the sedimentary one. The wide variations in δ³⁴S in sulfides and sulfates are due to changes in the physicochemical parameters of the ore-forming system (first of all, temperature and P_ch4) during the sulfate reduction. The regional hydrocarbon resources were sufficient for large-scale ore formation.     

Automated Extraction of a Five‐Year LA‐ICP‐MS Trace Element Data Set of Ten Common Glass and Carbonate Reference Materials: Long‐Term Data Quality,Optimisation and Laser Cell Homogeneity

LA‐ICP‐MS is increasingly applied to obtain quantitative multi‐element data with minimal sample preparation, usually achieved by calibration using reference materials (RMs). However, some ubiquitous RMs, for example the NIST SRM 61× series glasses, suffer from reported value uncertainties for certain elements. Moreover, no long‐term data set of analyses conducted over a range of ablation and tuning conditions exists. Thus, there has been little rigorous examination of the extent to which offsets between measured and reported values are the result of error in these values rather than analytically induced fractionation. We present new software (‘LA‐MINE’), capable of extracting LA‐ICP‐MS data with no user input, and apply this to our system, yielding over 5 years of data (~ 5700 analyses of ten glass and carbonate RMs). We examine the relative importance of systematic analytical bias and possible error in reported values through a mass‐specific breakdown of fourteen of the most commonly determined elements. Furthermore, these data, obtained under a wide range of different ablation conditions, enable specific recommendations of how data quality may be improved, for example the role of diatomic gas, the effect of differential inter‐glass fractionation factors and choice of transport tubing material. Finally, these data demonstrate that the two‐volume Laurin ablation cell is characterised by no discernible spatial heterogeneity in measured trace element ratios.     

Multi-factor sensitivity analysis on the stability of submarine hydrate-bearing slope

There are many factors affecting the instability of the submarine hydrate-bearing slope (SHBS), and the interaction with hydrate is very complicated. In this paper, the mechanical mechanism of the static liquefaction and instability of submarine slope caused by the dissociation of natural gas hydrate (NGH) resulting in the rapid increase of pore pressure of gas hydrate-bearing sediments (GHBS) and the decrease of effective stress are analyzed based on the time series and type of SHBS. Then, taking the typical submarine slope in the northern South China Sea as an example, four important factors affecting the stability of SHBS are selected, such as the degree of hydrate dissociation, the depth of hydrate burial, the thickness of hydrate, and the depth of seawater. According to the principle of orthogonal method, 25 orthogonal test schemes with 4 factors and 5 levels are designed and the safety factors of submarine slope stability of each scheme are calculated by using the strength reduction finite element method. By means of the orthogonal design range analysis and the variance analysis, sensitivity of influential factors on stability of SHBS are obtained. The results show that the degree of hydrate dissociation is the most sensitive, followed by hydrate burial depth, the thickness of hydrate and the depth of seawater. Finally, the concept of gas hydrate critical burial depth is put forward according to the influence law of gas hydrate burial depth, and the numerical simulation for specific submarine slope is carried out, which indicates the existence of critical burial depth.     

Os水吸收液ICP-MS测量信号强度衰减原因研究

蒸馏法能从样品中有效分离出OsO_4,吸收液直接用于ICP-MS测定,是辉钼矿Re-Os定年的关键技术环节。但实验发现,长时间放置的吸收液中Os信号强度显著降低。根据OsO_4化学性质推测原因在于一是挥发使吸收液Os含量减少,二是还原使+8价Os变成低价态,气态比例降低,若雾化效率不变,进入质谱仪的Os减少,两者都会导致信号降低,但具体影响情况不明,需深入研究。本文利用辉钼矿标准物质制备不同放置时间、酸度和温度的吸收液,对比上述条件对ICP-MS信号强度的影响。实验时将残余吸收液与稀释剂、氧化剂封入Carius管加热蒸馏,测定Os含量。结果表明:吸收液放置时间越长,酸度越低,温度越高,信号降幅越大,幅度达到3.2%~68.6%。室温下放置相同时间,低酸度吸收液的Os保存率高于高酸度吸收液,但Os信号强度低于后者,证明了挥发和还原共同导致信号衰减,且还原是主导原因。本文提出,冷冻(-18℃)可抑制OsO_4挥发,提高酸度(约3.5 mol/L)可减弱OsO_4还原,两者结合抑制信号衰减,提高了蒸馏法的灵活性和适用性。     

俯冲带碳酸盐化对深部碳循环的启示:以中国西南天山碳酸盐化云母片岩为例

俯冲带可将地球表层碳输送至深部地幔,同时也记录着俯冲板片来源碳质流体的迁移沉淀机制,对地球深部碳循环具有重大影响。近年来,俯冲带脱碳机制的研究表明流体溶解脱碳作用是冷的大洋俯冲板片释放COH流体的重要方式,而上覆板块(尤其地幔楔)则被认为是缓冲这些COH流体的重要场所,甚至是俯冲带CO_2的唯一"归宿"。事实上,俯冲带岩石本身的固碳能力却受到了忽视,而对俯冲带岩石捕获和固存CO_2(carbon capture and storage,CCS)能力的评估对全球碳通量的估算尤为重要。本文以中国西南天山高压-超高压变质带中碳酸盐化云母片岩为例,探讨俯冲带岩石的碳酸盐化对深部碳循环的影响。西南天山长阿吾子一带的碳酸盐化云母片岩记录了俯冲板片起源的碳质流体对俯冲带云母片岩的交代作用,地球化学特征表明蛇纹岩释放的富水流体溶解俯冲洋壳中的碳酸盐可能是产生COH流体的重要机制。基于碳质流体对多硅白云母(Si(a.p.f.u.)=3.58～3.73)的交代及相对高压的碳酸盐矿物(主要为白云石和菱镁矿)与金红石的共生,结合区域上碳酸盐化云母片岩与高压碳酸盐化蛇纹岩(HP-ophidolomite)的伴生,我们认为云母片岩的碳酸盐化作用可能发生在俯冲板片峰期稍后的高压折返阶段。俯冲带云母片岩的固碳作用表明除了上覆板块,俯冲带岩石本身对于碳质流体也具有很好的吸收能力。初步估算表明俯冲带云母片岩的碳酸盐化每年可固存至少2.46～6.68Mt/yr,约占俯冲板片每年进碳量的4%～17%。     

Hydrothermal Dolomite: A Review and PerspectiveEI北大核心CSCD

Hydrothermal dolomite commonly closely associates with oil-gas reservoirs and sediment-hosted Pb-Zn deposits, the Mississippi Valley-type (MVT) Pb-Zn deposits in particular. Host rocks of MVT deposits usually experienced extensive dolomitization, and indeed, hydrothermal dolomite is considered as a useful prospective indicator for MVT mineralization. However, genetic link between the hydrothermal dolomitization and MVT Pb-Zn mineralization is a matter of debate. This paper briefly reviewed the nomenclature and research history of hydrothermal dolomite, introduced the major geological, geochemical characteristics, and distribution of hydrothermal dolomite, spatial and possibly genetic relationship between hdyrothermal dolomite and hdyrothermal ore deposits and oil-gas reservoirs based on case studies including the occurrence of hydrothermal dolomites in MVT deposits in Southwest China. The temporal and genetic relationships between dolomitizaiton and thermal sulfate reduction, sulfide precipitation and thus the location of ore mineralization well worthy more attention, and comprehensive geological and isotope geochemical and state of art in situ techniques will contribute to understanding of the genesis of hydrotherml dolomite and the spatially related ore deposits and oil-gas reservoirs. © 2018, Science Press. All right reserved.     

尼泊尔低喜马拉雅推覆带油源对比及油气成藏

尼泊尔低喜马拉雅推覆带油气苗来源不清极大地影响了该区油气勘探.在地质-地球物理综合调查的基础上,利用油气地球化学、碳同位素及生烃史模拟对尼泊尔代莱克地区油源和成藏过程进行了研究.结果表明:①尼泊尔代莱克地区油苗产于Padukasthan断裂,可分两期,第一期呈含油断层泥产出,氯仿沥青"A"为149～231 μg/g,RR.为0.81％,氯仿沥青"A"的δ13C相对较重(-26.24‰～-27.10‰),族组分具有正碳同位素序列,发黄绿色荧光,为典型的低熟煤成油,第二期呈液态油产出并遭受微生物降解,金刚烷IMD指数为0.33～0.45,R.为1.24％～1.53％,3,4-DMD含量46％～47％,全油δ13C为-29.50‰～-29.45‰,族组分碳同位素趋于一致,发蓝色荧光,为海相成因高熟油;②第一期油来源于Surkhet群的Melpani组和Gondwana群煤系烃源岩,为Ⅲ型有机质低熟阶段的产物,第二期来源于Surkhet群的Swat组浅海陆棚相黑色页岩,为Ⅱ1型有机质生油高峰的产物,两期油与Lakharpata群过成熟黑色泥岩和Siwalik群未熟泥岩没有亲缘关系;③尼泊尔低喜马拉雅推覆带具有"多源多期、推覆增熟、砂体控储、披覆控聚"的油气成藏模式,油气成藏过程可划分为沉积浅埋、构造圈闭形成、深埋油藏形成、气藏形成和晚期改造定型5个演化阶段;④尼泊尔低喜马拉雅推覆有利于Gondwana群、Surkhet群深埋增温、持续快速生烃和晚期成藏,对比邻区巴基斯坦的含油气盆地,尼泊尔低喜马拉雅推覆带及相邻类似地区具备良好的油气成藏条件.