呼和湖凹陷中低煤阶煤系烃源岩地球化学特征及生烃潜力评价

GEOCHEMICAL CHARACTERISTICS AND HYDROCARBON-GENERATING POTENTIAL OF COAL-BEARING SOURCE ROCK WITH MIDDLE TO LOW COAL RANK, HUHEHU DEPRESSION

通过有机地球化学和有机岩石学方法并结合热模拟实验,探讨了呼和湖凹陷煤系烃源岩的生烃潜力。研究结果表明:该区煤系烃源岩有机质丰度总体达到中等—好烃源岩标准;有机质类型以腐殖型为主,镜下显微组分以基质镜质体为主;大部分烃源岩处于中低煤阶。煤与煤系泥岩地化特征相似,生物标志化合物显示煤层主要来源于高等植物。热模拟实验总产烃量与热解生烃潜量基本一致,而生烃过程体现了煤系源岩多阶段生烃的特点,展示了该区煤系烃源岩较大的生烃潜力。该区煤层厚度较大分布范围广,油气资源潜力大,应围绕煤层进行煤成气藏、煤成油藏和煤层气勘探。

The hydrocarbon-generating potential of coal-bearing source rock, Huhehu Depression, was analyzed by means of some methods of both organic geochemistry and petrology along with thermal model experiment. Re-sults show that(1) for the source rock, its organic-matter abundance achieves a standard of middle to good one;(2) for the organic matter, its type is mainly humic one, and microscopic maceral is dominantly degradinite; and(3) most of source rock ranges from middle to low coal rank. For both coal and coal-bearing mudstone, their geochemical charac-teristics are similar and their biomarker appears that coal seam was originated mainly from higher plants. From thermal model experiment, it is found that total hydrocarbon-generating content is basically consistent with pyrolysis hydrocar-bon-generating potential. In addition, its generating process reflects a feature of multiple-stage generating hydrocar-bon for coal-bearing source rock, also showing a large hydrocarbon-generating potential. In the study area, there is a huge potential of oil and gas resources because of wide distribution of coal seam with big thickness.