Recognition of a hydrothermally linked oil accumulation process in the Tahe oil field, northwestern China, with organic geochemistry, Re-Os, and U-Pb geochronology

IF 2.7 3区地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY

AAPG Bulletin Pub Date : 2024-08-01 DOI:10.1306/02132422124

Shaojie Li, Xiaowen Guo, Bin Wang, Zicheng Cao, Hao Xu, Jiaxu Chen

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引用次数: 0

Abstract

The Tahe oil field is one of the largest deeply buried, multistage-charged Paleozoic oil fields in the Tarim Basin, northwestern China. Understanding the temporal evolution of Paleozoic oils is crucial for petroleum prospecting in this region. In this study, a combination of biomarker analysis, stable/radiogenic isotopic analysis, and Re-Os and U-Pb isotope geochronology is used to constrain the timing of oil accumulation in the Tahe oil field. Coexistence of unresolved complex mixture and intact n-alkane series in oil chromatograms suggests the presence of multistage oil accumulation processes in the studied area, and paleo-biodegradation occurred prior to the latest oil charge. Biomarker data show that the source rock for the latest accumulated oils was deposited in a marine reducing–weakly oxidizing environment. An early Permian oil generation event (276 ± 35 Ma) was suggested by Re-Os geochronology. This oil generation event is responsible for the late Permian–Late Triassic charge event (259.9–224.1 Ma), which is identified with in situ U-Pb isotopic analysis of calcites containing primary oil inclusions. These age data provide direct temporal constraints for the latest oil accumulation in the Tahe oil field. Furthermore, C-O-Sr-Os isotopic results show that hydrothermal fluid flowed during this oil accumulation event. Outcomes of this study unravel the Re-Os isotopic analysis of cogenetic crude oils and have the potential of direct dating the latest, hydrothermally linked oil accumulation in multistage-charged deep oil reservoirs.

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利用有机地球化学、Re-Os 和 U-Pb 地球年代学识别中国西北塔河油田的热液关联石油积累过程

塔河油田是中国西北部塔里木盆地最大的深埋多级充注古生代油田之一。了解古生代石油的时间演化对该地区的石油勘探至关重要。本研究结合生物标志物分析、稳定/放射同位素分析以及Re-Os和U-Pb同位素地质年代学，对塔河油田的石油累积时间进行了约束。石油色谱中未解决的复合混合物和完整的正烷烃系列并存，表明研究区域存在多级石油积累过程，古生物降解发生在最近一次石油充注之前。生物标志物数据表明，最近一次石油累积的源岩是在海洋还原-弱氧化环境中沉积的。Re-Os地质年代学表明，二叠纪早期（276 ± 35 Ma）发生过一次石油生成事件。这一石油生成事件是晚二叠世-晚三叠世充填事件（259.9-224.1 Ma）的原因，通过对含有原生石油包裹体的方解石进行原位 U-Pb 同位素分析，确定了这一充填事件。这些年龄数据为塔河油田最近的石油积累提供了直接的时间约束。此外，C-O-Sr-Os 同位素分析结果表明，热液曾在这一石油积累过程中流动。这项研究的结果揭示了同生原油的 Re-Os 同位素分析，有可能直接确定多级充注深层油藏中热液关联的最新石油积累的年代。

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来源期刊

AAPG Bulletin 工程技术-地球科学综合

CiteScore

6.60

自引率

11.40%

发文量

审稿时长

4.8 months

期刊介绍： While the 21st-century AAPG Bulletin has undergone some changes since 1917, enlarging to 8 ½ x 11” size to incorporate more material and being published digitally as well as in print, it continues to adhere to the primary purpose of the organization, which is to advance the science of geology especially as it relates to petroleum, natural gas, other subsurface fluids, and mineral resources. Delivered digitally or in print monthly to each AAPG Member as a part of membership dues, the AAPG Bulletin is one of the most respected, peer-reviewed technical journals in existence, with recent issues containing papers focused on such topics as the Middle East, channel detection, China, permeability, subseismic fault prediction, the U.S., and Africa.