Abstract: The evolution of mechanic characteristics of Shahejie source rocks and its effects to hydrocarbon expulsion in Shahejie Formation of Jiyang Depression were analyzed by using diagenism.X-ray diffraction and petrography analysis showed that the burial depth from 2500 meters to 3000 meters was favorable to diagenetic evolution of clay and carbonate minerals in source rock.The rapid conversion of the illite-montmorillonite interlayer minerals occurred in the depth from 2000 meters to 3000 meters,and the strong recrystallization of carbonate minerals happened in the burial depth from 2500 meters to 3100 meters.The conversions of interlayer and carbonate minerals had a clear influence on the mechanic characteristics of source rocks,which resulted in the source rocks changing from relatively more plastic to relatively more brittle with the burial depth increasing.The changes of mechanic characteristics of source rocks improved the development of micro-fractures in the deep source rocks and also had a great influence on hydrocarbon expulsion and expulsion process of source rocks.

Key words: Jiyang Depression, evolution of source rocks, clay minerals, carbonate minerals, micro fracture

摘要： 从成岩作用角度,分析了济阳断陷盆地沙河街组烃源岩力学性质的演化及其对排烃过程的影响。X-衍射和岩石微观特征分析表明,埋藏深度为2 500~3 000m是烃源岩中两类重要矿物成岩演化的重要阶段。其中:粘土矿物中伊蒙混层矿物迅速转化发生在2 000~3 000m;原生碳酸盐大量重结晶发生在2 500~3 100m。粘土矿物和碳酸盐矿物的转化对烃源岩力学性质产生了影响,导致随埋藏深度的增加岩石由相对塑性向相对脆性转变。烃源岩力学性质的这种变化促进了深层烃源岩中微裂隙的发育,并对烃源岩的排烃方式和排烃过程产生了重要影响。

关键词: 济阳坳陷, 烃源岩演化, 粘土矿物, 碳酸盐矿物, 微裂隙