Hu Yanlong, Wang Ruyue, Huang Yahao, Luo Jing, Li Shaojie, Wen Zhigang, Guo Xiaowen, Tao Ze, Liu Yukun, Yi Yan
Key Laboratory of Exploration Technologies for Oil and Gas Resources of Ministry of Education, Yangtze University, Wuhan, 430100, China.
SINOPEC Petroleum Exploration and Production Research Institute, Beijing, 102206, China.
Sci Rep. 2025 Mar 4;15(1):7582. doi: 10.1038/s41598-025-91727-0.
In petroliferous sedimentary basins, the interplay between CO and hydrocarbons exerts a notable influence on hydrocarbon generation and accumulation. This research focuses on the Huangqiao oil and gas reservoir, which is known for hosting the largest CO reserves in China. U-Pb isotopic dating of calcite veins in fractures, carbon and oxygen isotope analyses, along with rare earth element (REE) analysis were applied to elucidate the chronology and origin of inorganic and organic fluids in the studied area. Petrographic observations revealed the presence of various components of fluid inclusions, including gaseous CO, gaseous CH, CH-CO mixtures, and hydrocarbon fluids. Besides, through Raman quantitative measurements and thermodynamic simulations, the density, composition, pressure, and temperature characteristics of CH and CO bearing fluid inclusions were calculated. Based on the entrapment conditions of fluid inclusions and U-Pb dating results, two stages of hydrocarbon charging were identified: an early-Jurassic stage (approximately 200-185 Ma) characterized by mid-maturity oil and CH and an early-Eocene stage (approximately 61-41 Ma) marked by high-maturity oil and CH. CO accumulation events were divided into two stages: high-density CO fluid activity during the early Eocene (approximately 59-39 Ma) and low-density CO fluid activity during the Tertiary-Quaternary (approximately 23-4 Ma). Moreover, deep fluid influx into reservoirs led to hydrothermal alteration, as evidenced by anomalously high homogenization temperatures and vitrinite reflectance. CO has an extraction effect on crude oil, where its late entry primarily results in the removal of lighter components, especially CH. When high-temperature hydrothermal CO fluid enters the oil reservoir, it accelerates the cracking of crude oil and alters the fluid's composition. This thermal event also speeds up the source rock's thermal evolution, leading to extraction, pyrolysis, and gas displacement throughout the reservoir's development process. This study presents a comprehensive approach for quantitatively studying geological fluids in petroliferous basins of this nature.
在含油气沉积盆地中，CO与烃类之间的相互作用对烃类生成和聚集具有显著影响。本研究聚焦于黄桥油气藏，该油气藏以拥有中国最大的CO储量而闻名。通过对裂缝中方解石脉进行U-Pb同位素测年、碳氧同位素分析以及稀土元素（REE）分析，以阐明研究区域内无机和有机流体的年代学及成因。岩相学观察揭示了流体包裹体的各种成分，包括气态CO、气态CH、CH-CO混合物以及烃类流体。此外，通过拉曼定量测量和热力学模拟，计算了含CH和CO流体包裹体的密度、成分、压力和温度特征。基于流体包裹体的捕获条件和U-Pb测年结果，确定了两个阶段的油气充注：早侏罗世阶段（约200 - 185 Ma），以中成熟度的油和CH为特征；早始新世阶段（约61 - 41 Ma），以高成熟度的油和CH为特征。CO聚集事件分为两个阶段：早始新世期间（约59 - 39 Ma）的高密度CO流体活动以及第三纪 - 第四纪期间（约23 - 4 Ma）的低密度CO流体活动。此外，深部流体流入储层导致了热液蚀变，异常高的均一温度和镜质体反射率证明了这一点。CO对原油有萃取作用，其后期进入主要导致较轻成分尤其是CH的去除。当高温热液CO流体进入油藏时，它加速了原油的裂解并改变了流体成分。这一热事件还加速了烃源岩的热演化，在整个油藏开发过程中导致萃取、热解和气驱。本研究提出了一种定量研究此类含油气盆地中地质流体的综合方法。
