【作者】 吴艳艳；

【导师】 秦勇；

【作者基本信息】 中国矿业大学 ， 地球化学， 2011， 博士

【摘要】 本文基于黔西-滇东地区上二叠统煤样,采用油气地球化学、煤岩学、矿物学、催化化学等的理论与方法,以原煤及原煤+黄铁矿和（或）过渡金属元素Mo的催化生气热模拟实验为主要手段,探讨了煤中矿物/金属元素催化生气的行为、过程和地球化学机理,取得如下创新性认识:第一,鉴识了黔西-滇东晚二叠世煤中具有潜在催化生气作用的矿物和金属元素的产出特征。煤中含有理论上具有催化作用的矿物和过渡金属元素,矿物以黄铁矿和高岭石最为常见,Ti、V、Cr、Mn、Co、Ni、Y、Z r等的算术平均含量高于中国煤平均值。其中,多数煤样中单一或多种过渡金属元素含量高于全国平均值3倍以上,Mn、Ni、Co的含量存在较大差异。第二,发现煤中矿物/过渡金属元素使原煤有机质具有更大的生烃潜力。黄铁矿对甲烷具有显著的正催化作用;同时加入黄铁矿和Mo时,煤层气含有更多数量的重烃气,并有利于烯烃的产出;Mo对C_7～14具有显著的催化作用,但同时有黄铁矿的参与则会使C7～C14产率降低;黄铁矿/Mo的加入,影响到芳烃的产率高峰;较高的过渡金属单质含量对煤中本身含有的硫元素转化为H₂S气体有抑制作用。在中～高温度范围内,催化剂对有机质生烃具有催化作用,升温条件能明显影响黄铁矿对芳烃、饱和烃和沥青质的催化作用,反映古地温场条件是催化生烃的一个重要影响因素。此外,随着模拟温度的增加,4个样品系列均表现出Pr/nC₁₇、Ph/nC₁₈和Pr/Ph比值降低的共同特征。第三,就催化生烃过程中碳同位素的演化规律取得某些新的认识。研究发现,催化气δ¹³C₁变化范围与华南煤层气δ¹³C₁分布范围一致,黄铁矿与Mo的加入明显使δ¹³C₁偏重。模拟温度增加,甲烷同位素经历了先变轻再变重的过程。同一温阶产生的甲烷及其同系物,具有δ¹³C₁<δ¹³C₂<δ¹³C₃的特征。第四,分析了煤中矿物/金属元素催化生烃的动力学过程,建立了催化成因煤层气判识模式。该模式由矿物/元素地球化学和油气地球化学指标构成。计算了催化生气过程中甲烷及总气态烃生成的动力学参数,发现原煤+矿物/金属元素可降低生气所需要的反应活化能,从而对甲烷生成起到催化作用。结合研究区上二叠统煤层埋藏-受热史,估算了不同地质时期煤的原始催化产气率。在此基础上,综合煤中矿物种类、过渡金属元素含量和煤的热演化程度,初步预测了区内煤层气富集区带分布。更多还原

【Abstract】 The gas formation mechanism catalyzed by mineral/metal elements were discussed and studied based on the coal from late Permian in Eastern Yunnan and Western Guizhou, using gas geochemistry, coal petrology, mineralogy, catalytic chemistry etc., and combining with the thermal simulation experiment of coal alone and the coal in present of pyrite or Mo,. Innovative understanding is as followings:（1） The output characteristics of minerals and metal elements which have potential catalysis during gas generation in coal of late Permian from Eastern Yunnan and Western Guizhou were identified. The coals contain the minerals that are catalytic in theory. Pyrite and kaolinite are the main minerals. The content of Ti, Cr, Mn V, Co, Ni, Y, and Zr and elements are higher than the average level of China coal. Solo or manifold transition metal elements contents in most coal seams are over 3 times higher than national average. The occurrences of Mn, Ni and Co in coal are various.（2） Mineral/elements made the coal organic have greater potential during hydrocarbon generation. Pyrite mainly had a positive and significant catalytic role to the methane. Adding the pyrite and Mo at the same time made the coal samples generate heavier hydrocarbon gases, and pyrite and Mo were helpful to the olefins output. Transition metal Mo had remarkable catalytic effect on the C_7～14 forming, but if there were also pyrite exist at same time, it would make C_7～14 reduce. Pyrite and Mo influenced aromatics hydrocarbon and asphalt qualitative yield peak. High content of transition metal elementals can inhibit the H₂S forming from the sulfur of coal itself. Catalysts had catalysis of hydrocarbon generation in middle to high temperature range. Heating rate affected the pyrite catalysis for saturated hydrocarbons, aromatic hydrocarbon and asphalt, reflecting geological geothermal conditions was an important influence factors for mineral/elements catalysis in the generation of hydrocarbons. Pr/nC17,Ph/nC18 and Pr/Ph were decreased along with the increase of temperature.（3） Some new understanding on evolution law of carbon isotopes during the catalytic hydrocarbon-generating process was obtained. Results show that theδ¹³C₁ changed in theδ¹³C₁ change range of south China coal. Pyrite and Mo made theδ¹³C₁ value heavier.δ¹³C₁ had the same change way which was decreases at first, and then increases along with the increase of temperature. The gas carbon isotope have the same characteristics which isδ¹³C₁<δ¹³C₂<δ¹³C₃. （4） The dynamic process of the hydrocarbon generation by minerals/metal elements catalysis was analyzed and identified mode of coal bed methane generation by minerals/ metal elements catalysis which was composed by minerals/metal elements geochemical characteristics and geochemical index of oil and gas was established. The dynamic parameters of methane and the total gaseous hydrocarbon generation were calculated. The results show that activation energy significantly reduced in presence of mineral/metals, which proved that minerals/metal elements have catalysis during methane formation. Combining with buried evaluation process of Permian coal in studied area, original gas yield from different historical periods were estimated. On this basis, combining with the minerals variety, transition metal elements contents and the evolution stages of coal, coal bed methane favorable exploration areas were forecasted primarily.更多还原