鄂尔多斯盆地侏罗纪含煤岩系生烃潜力评价

The assesment of the capacity for producing hadrocarbon in the Jurrasic coal and associate rocks in Ordos basin

采用有机岩石学与显微煤岩学的方法对鄂尔多斯盆地含煤岩系中不同有机质的地球化学特征进行详细研究,进而对不同烃源岩的生烃潜力进行评价。研究结果显示鄂尔多斯盆地中,有机质类型主要是Ⅲ型和Ⅱ2-Ⅲ型干酪根,煤中显微组分中惰质组占绝对优势,壳质组含量少,仅在部分地区镜质组含量较高(如:宁夏汝箕沟、陇东地区等);盆地中除了腐殖型干酪根外,也有部分属于腐泥型有机质,如盆地南部黄陵矿区的烛煤,其中脂类含量丰富。根据对盆地侏罗纪含煤岩系的有机质的丰度、类型和成熟度(热演化程度)的分析和研究得知:煤、炭质泥岩和暗色泥岩的有机质丰富,但煤和泥岩的转化系数均接近或低于生油岩的下限,其族组成中以中高含量的沥青质、中含量的非烃和芳烃、低含量的饱和烃为特征,且煤的有机质丰度远高于泥岩。盆地中侏罗纪延安组有机质只达到低—中成熟阶段的前期,以低成熟阶段为主,反射率Ro=0.37%～0.70%;盆地内的煤系及炭质泥岩均具有良好的生烃潜力,在盆地南部的环庆向斜区形成工业价值油气藏的潜力最大。

Studied the organic geochemical characteristics of different organic matters from Ordos basin by means of organic geochemical method and coal petrological method,and estimated the hydrocarbon-generation potential of different hydrocarbon source rocks.The results show that,in Erdos basin,the organic matters＇ type are kerogen typeⅢ andⅡ2-Ⅲ.The inertinite in coal＇s macerals are predominant,and the content of exinite is low.The exinite is relatively accumulated in parts,for example Rujigou and Longdong Ningxia Province etc.Besides the humic kerogen,there are also some sapropelic kerogens,for example the cannels in Huangling mining area south basin contain lots of lipid.Based on the studying of the abundances,type and maturity of Jurassic coal-buried seam organic matters in Erdos basin,it is found that the coal,carbargilite and dark mudstone contain abundant organic matters,but conversion coefficient of coal and mudstone all are close to or lower than the limit of source rock.The samples contain high level of bitumen,medium level of non-hydrocarbon and low level of saturated hydrocarbon and the organic matters＇ abundances in coal is great higher than mudstones＇.The organic matters in Yanan formation in middle Jurassic of Erdos basin is in the former period of low-middle maturity,and mainly in low maturity（Ro=0.37%~0.70%）.The coal-buried seam and carbargilite in Erdos basin all have great hydrocarbon-generation potential,especially Huanqing syncline area in south basin which has the most potential to form oil and gas accumulation that are of industrial value.