烃源岩非均质性及其意义——以中国元古界下马岭组页岩为例

摘要

以中国元古界下马岭组页岩为例,基于野外露头、镜下观察和地球化学特征分析,对不同尺度的烃源岩非均质性及烃类的微观赋存特征进行研究.岩石圈板块运动和古纬度位置导致烃源岩宏观旋回性和非均质性,天文轨道力控制的气候变化可能是导致烃源岩微观非均质性的最主要原因.因此,烃源岩非均质性是恒定存在的,不仅体现为有机质含量的差异,还包括碎屑物来源和孔隙度的差异.在油气资源评价,尤其是非常规油气资源评价时需要充分考虑烃源岩的非均质性.烃源岩非均质性特征为油气生成、排驱和储集提供了良好的“源储组合”,为估算非常规油气经济可采储量提供了新的参考指标.因此烃源岩非均质性的定量化研究对非常规油气形成机理及资源量预测具有重要意义.%Taking Mesoproterozoie Xiamaling Formation,Northern China as an example,the heterogeneities of source rock in different scales and hydrocarbon microscopic occurrence are studied based on observation of outcrops and observation with microscopy,and geochemical analysis.The large scale heterogeneities of source rocks are considered to be controlled by the plate movement and paleo-latitude location,while the micro-scale might be controlled by climate changes driven by the astronomical orbit.The constant existence of heterogeneities includes the differences of organic matter,debris sources and porosities.The heterogeneities of source rock should be seriously treated during the evaluation of oil and gas resources,especially the unconventional oil and gas.This kind of heterogeneous source rocks provides excellent source-reservoir assemblage of oil and gas generation,expulsion and accumulation,and new reference indexes for the economic evaluation of unconventional oil and gas.Therefore,quantitative study of the heterogeneity of source rock is of great significance for investigating formation mechanism and resource estimation of unconventional oil and gas.