南堡凹陷烃源岩有机碳含量恢复研究  

TOC Recovery of Source Rock in Nanpu Sag

作　　者：冯乾乾[1] 韩一哲 李倩文[1,2] 庞雄奇[2,3] 

机构地区：[1]中国石油大学(北京)地球科学学院,北京102249 [2]中国石油大学(北京)盆地与油藏研究中心,北京102249 [3]中国石油大学(北京)油气资源与探测国家重点实验室,北京102249

出　　处：《非常规油气》2016年第2期33-39,共7页Unconventional Oil & Gas

摘　　要：烃源岩进入成熟阶段后随着大规模生排烃作用的进行,TOC含量逐渐减少,将烃源岩内残余TOC恢复至生排烃前的原始状态有助于正确评价一个地区的烃源岩。南堡凹陷发育沙河街组和东营组两套烃源岩,有机质类型主要为Ⅱ型,R_o主要为0.5%~1.4%,处于成熟—高成熟阶段;根据烃源岩演化过程中残余生烃母质变化原理,利用烃源岩TOC演化与各种主控因素之间的定量关系模型,对模型中烃源岩密度、孔隙度、油气发生率、生成烃类的含碳系数、排烃系数等因素在自然条件下变化的特征进行取值,计算得到了南堡凹陷烃源岩不同成熟度下的TOC恢复系数,并制作了恢复图版,研究证实,烃源岩残余有机碳恢复系数可达1.67。说明进入了排烃门限的低有机质丰度（TOC〈0.5%）烃源岩不应被排除在有效烃源岩之外,其可能对南堡凹陷油气藏的形成和分布具有重要贡献。In the process of geologic history, the amount of TOC gradually decreases with the mass hydrocarbon expulsion after the source rock enters mature stage. Therefore, it may contribute to evaluate the source rock in an area accurately if the residual amount of TOC in present source rock is restored to the condition where the source rock hasn＇ t expelled hy- drocarbon. Study showed that there were two sets of source rocks in Nanpu sag, namely, the Shahejie Formation and the Dongying Formation. The organic matter type of them was mainly type II and the Ro of them ranged from 0. 5% to 1.4%, which indicated that the source rocks were at the mature and highly mature stage. Based on the principle of the changes that the residual organic matter in the source rocks made in the evolution process of the source rock, a quantitative model about the amount of TOC and various main controlling factors was proposed. By given a proper value of each factor like source rock density, porosity, oil and gas incidence, carbon coefficient and expulsion coefficient of generated hydrocarbons in nat- ural conditions, the value of TOC recovery coefficient at different thermal maturity degree in source rocks of Nanpu Sag could be calculated and the result of which was 1.67. Based on this, the evolution chart of TOC in the source rocks was also established. It was revealed that the source rocks of low organic matter abundance （ TOC〈0. 5% ） that have entered expulsion threshold should not be excluded from effective source rocks. They might contribute a lot to formation and distribution of hydrocarbon reservoirs in Nanpu sag.

关 键 词：南堡凹陷 TOC恢复 烃源岩 烃源岩评价 

分 类 号：P618.13[天文地球—矿床学]