裂谷盆地生油层中火山岩及其矿物与有机质的相互作用——油气生成的催化和加氢作用研究进展及展望

HYDROCARBON GENERATION IN RIFT BASINS, EASTERN CHINA:CATALYSIS AND HYDROGENATION — INTERACTION BETWEEN VOLCANIC MINERALS AND ORGANIC MATTER

我国裂谷盆地生油层中常有火山岩发育。在研究它们共生模式的基础上，利用地球化学和模拟实验等手段探索埋藏成岩期火山矿物与有机质的相互作用。初步成果表明，一些火山矿物对有机质生烃具有催化和加氢作用，可以使生油岩在较低温度和压力条件下生成较多的油气。但是不同火山矿物对油气生成的催化加氢效果及其动力学特征、这种成因类型的油气识别方法、成藏模式等，还需深入研究。因此，本研究对于丰富油气成因理论、提供新的找油领域具有重要意义。

Major oil reserves in rift basins in eastern China are correlated with high quality source rocks. The high quality source rocks and their hydrocarbon generation are often related to volcanic activity in the basins. Three kinds of volcanic rocks in source rocks have been defined in the Songliao, Bohaiwan and North Jiangsu basins. Some of the volcanic rocks were formed in lacustrine environments during the deposition of source rocks. It is remarkable that a part of volcanic-derived materials serves as a source of nutrients for lacustrine organisms which resulted in the formation of the organic matter in source rocks with high organic carbon contents. Besides hydrothermal alteration, the volcanic minerals contributed catalysis and hydrogen to thermal degradation of organic matter into hydrocarbons during burial and diagenesis of source rocks and volcanics. A series of thermal simulations are performed with various combinations of immature source rocks and natural mineral assemblages. Results indicate that a significant volume of hydrogen was produced from the source rock mixed with olivine and zeolite; moreover, this combination provided a 3-fold increase in hydrocarbons. It is proposed that catalysis and hydrogenation by the volcanic minerals promote hydrocarbon generation, although organic matter type is significant variables. Hydrocarbons are generated at a lower degree of thermal stress when the reaction mixture contains volcanic minerals, plus have a heavier carbon isotopic composition, compared to the control set of experiments.