粘土矿物对有机质生烃的催化作用

Catalysis of Clay Mineral to Organic Matter in Hydrocarbon Genesis

烃源岩的有机质主要以有机粘土复合体的形式存在。有机质生烃是一种有机粘土化学反应。反应过程中,有机质与粘土之间存在质子和电子迁移,粘土通过对水分子的吸附和离解为有机质加氢裂解提供H+,而有机质生成的有机酸激活了粘土的催化活性,也为蒙皂石伊利石化反应创造了条件。烃源岩不同粘土矿物的选择性催化特征是影响油气组成的最重要因素。粘土的催化活性大小和发育时间是决定烃源岩生烃潜力大小的因素。由于烃源岩在蒙皂石伊利石化阶段具有最大的催化活性,而且与有机质生烃反应同步,因此富含伊$蒙混合层的烃源岩是世界含油气盆地的最有利烃源岩。不同地质时期的烃类地质储量与烃源岩膨胀性粘土的丰度有密切关系。

Organic matter in source rock exits mostly as clay-polymer complexes. Hydrocarbon generation from organic matter is a process of chemical reaction of organic clay, during which, migration of proton and electron occurs between organic matter and clay mineral. By adsorbing and dissociating water molecule on clay faces, clay provides H^＋ for hydrogenating pyrolysis of organic matter while organic acid yielded from organic matter activates catalytic activity of clay and creates condition to the smectite illitization, Selective catalysis of different clay minerals within source rock is the most important factor of affecting hydrocarbon composition. Extent and developing time of clay catalytic activity determine the hydrocarbon-generating potential. Due to source rock has the most active catalysis during smectite illitization with synchronous reaction of orgarlic matter in hydrocarbon generation, the rocks with abundant I/S mixed layers are the most favorable source rock to generate hydrocarbon in oil and gas basins in the world. The quantities of hydrocarbon reserves in-place during different geologic stages have a close relation with the abundance of expansive clays in source rocks.