排烃门限存在的地质地球化学证据及其应用  

Geochemical Evidences of Hydrocarbon Expulsion Threshold and Its Application

作　　者：庞雄奇[1] 李素梅[1] 金之钧[1] 黎茂稳[1] 

机构地区：[1]石油大学石油与天然气成藏机理教育部重点实验室

出　　处：《地球科学（中国地质大学学报）》2004年第4期384-390,共7页Earth Science-Journal of China University of Geosciences

基　　金：国家重点基础研究发展规划项目 (G199943 3 10 ) ;国家"十五"攻关课题 ( 2 0 0 1BA60 5A0 9) .

摘　　要：排烃门限概念的提出为有效源岩的判识奠定了理论基础 ,它在油气勘探与资源评价中具有重要意义 .采用地球化学的方法论证了排烃门限的客观存在 .研究表明 ,源岩进入排烃门限后 ,其反映生烃潜能的指标 (S1+S2 ) /TOC、氢指数以及反映烃源岩残留烃量的指标氯仿沥青“A”都开始明显降低 ;烃源岩中可溶有机质的化学成分、生物标志物的含量与分布特征也都发生明显的变化 ,没有进入排烃门限的源岩可溶有机质与原油差别大 ,进入门限后的源岩可溶有机质开始与原油组分较为一致 .渤海湾盆地东营凹陷沙四段泥岩和页岩的排烃门限分别为 2 2 0 0m和 2 0 0 0m左右 ,排烃强度分别为 0～110 0kg/m2 和 0～ 15 0kg/m2 ,累积排出烃量为 7.36 5× 10 8t和 1.4 35× 10 8t.The concept of hydrocarbon expulsion threshold is taken as an important theoretical base in the identification of effective source rock, and therefore, plays a significant role in petroleum exploration and resource assessment. Occurrence of hydrocarbon expulsion threshold is discussed by means of geochemical approaches. The results show that the parameters of (S1+S2)/TOC, HI showing source rock potential and the abundance of resident hydrocarbons-A decrease obviously with increasing depth once source rocks reach the expulsion threshold, and obvious variation of chemical composition as well as abundance and relative distribution of biomarkers can also be observed. Similar chemical compositions between crude oils and soluble organic matters are observed after the source rocks entered the expulsion threshold, however, the discrepancies are present within the source rocks below the expulsion threshold. Taking as an example of the Dongying depression of the Bohaiwan basin, the expulsion thresholds of Es4 mudstone and shale in Bamianhe area are about 2200 and 2000 m respectively, with expulsion intensity of 0 - 1100 and 0 - 150 kg/m2 and expulsed accumulative hydrocarbons of 7.365 × 108 and 1.435 × 108 t.

关 键 词：排烃门限 资源评价 生烃潜力 烃类组分 生物标志物 

分 类 号：P618.130[天文地球—矿床学]