摘要
柴达木盆地西北区(柴西北)新近系已取得显著勘探成果,资源潜力巨大,但关于烃源岩发育与有机质差异富集机理的研究相对较少,制约了勘探进程。选取研究区新近系4组烃源岩典型样品,分析其地球化学特征,并探讨烃源岩发育及有机质富集与古盐度、古生产力、氧化还原条件和沉积速率的关系。结果表明:研究区新近系烃源岩母质类型以Ⅱ型有机质为主,其次为Ⅲ型有机质,生烃母质主要为褶皱藻和皱球藻等原地水生生物与陆源有机质。新近系烃源岩的发育与有机质富集主要受控于古生产力、古盐度和沉积速率。生产力越大,越利于有机质富集,烃源岩的TOC越大;随着盐度增大和沉积速率升高,烃源岩有机质丰度具有先增大后减小的特征;还原程度越强,烃源岩TOC值越高。只有在高的古生产力、适当的古盐度和适当的沉积速率背景下,才利于有机质富集。在此基础上,建立柴西北新近系烃源岩的发育模式,优质烃源岩主要分布在沉积中心附近的缓坡带。研究为咸化湖盆烃源岩的研究提供了一定的理论指导。
The Neogene of the northwestern Qaidam Basin has made significant exploration achievements and has great resource potential.However,relatively few studies on the development of source rocks and the mechanism of differential enrichment of organic matter restrict the exploration process.This paper selected the typical source rocks of the four Neogene groups,analyzed the geochemical characteristics of the source rocks,and the relationship between the source rock development and organic matter enrichment of the mud source rocks and the paleosalinity,paleo-productivity,redox conditions and deposition rate was discussed.The results show that the hydrocarbon source rock of the Neogene in the study area is mainly composed of type Ⅱ organic matter,followed by type Ⅲ organic matter.The hydrocarbon source rock is mainly composed of indigenous aquatic organisms such as Ruplegia and Chlorella and terrestrial organic matter.The development and organic matter enrichment of Neogene source rocks are mainly controlled by paleoproductivity,paleosalinity and deposition rate.The higher the productivity,the more conducive to the enrichment of organic matter,and the greater the TOC of source rocks.With the increase in salinity and deposition rate,the abundance of organic matter in source rocks increases first and then decreases.The greater the reduction degree,the higher the TOC of the source rock.Only under the background of high paleo-productivity,proper paleo-salinity and proper deposition rate can the sedimentary organic matter be enriched.On this basis,the development model of Neogene source rocks in the northwestern Qaidam basin is established.The high-quality source rocks are mainly distributed in the gentle slope near the sedimentary center,which provides some theoretical guidance for the study of source rocks in saline lacustrine basin.
作者
王波
吴志雄
周飞
李雅楠
张皓
崔海栋
曾旭
徐文君
WANG Bo;WU Zhixiong;ZHOU Fei;LI Yanan;ZHANG Hao;CUI Haidong;ZENG Xu;XU Wenjun(Research Institute of Exploration and Development,PetroChina Qinghai Oilfield Company,Dunhuang 736202,China;Plateau Saline Lacustrine Basin Oil-Gas Geology Key Laboratory of Qinghai Province,Dunhuang 736202,China;Research Institute of PetroChina Exploration and Development,Beijing 100083,China;Production and Operation Division,PetroChina Qinghai Oilfield Company,Dunhuang 736202,China)
出处
《天然气地球科学》
CAS
CSCD
北大核心
2023年第3期496-509,共14页
Natural Gas Geoscience
基金
中国石油“十四五”前瞻性基础性项目“柴达木盆地山前冲断带成藏规律及勘探方向研究”(编号:2021DJ0305)资助.
关键词
烃源岩
咸化湖盆
古环境
盐度
有机质富集
柴西北
Source rock
Salty lacustrine
Paleo environment
Salinity
Development mechanism
Northwestern Qaidam Basin
