近日，南京大学曹剑团队研究了碱性盐湖源岩独特的双峰生油：有机-无机相互作用的证据、模型和机制。该研究于2025年4月21日发表在《中国科学：地球科学》杂志上。

准噶尔盆地凤城组碱性盐湖烃源岩是一种新型优质陆相烃源岩。这些烃源岩的生烃模型仍有待开发，这是陆相生烃理论研究中的一个关键科学问题。为了填补知识空白，研究组基于生物环境协同进化和有机-无机相互作用的研究思路进行了全面的研究。他们研究了碱性盐湖源岩生烃的各个方面，包括自然剖面、人工剖面、动力学、储层油气特征标定、流体包裹体分析以及相关的地质和地球化学分析。从证据、机制、内涵和意义等方面对生烃模型进行了深入探索和建立。

结果表明，这种烃源岩表现出独特的两个生烃峰，以石油而非天然气为主，石油生烃峰在成熟和高成熟阶段，这与经典的天梭生烃模型不同。这是由于碱性湖泊独特的沉积环境及其生物群和无机矿物，导致了生物环境和有机无机相互作用。两种主要的有机物前体，即杜氏藻和蓝藻，为两个生烃高峰提供了物质。碱性矿物通过皂化反应影响生烃过程，导致更长的生油窗口和更高的生油收率。盐度和pH值影响了有机物的热演化，从而延缓了碳氢化合物的演化。

烃源岩埋藏过程中的两个抬升阶段进一步促进了生烃的两个高峰。碱性盐湖烃源岩能有效生成烃类，形成独特的环烷油，为整个石油系统提供了资源基础。碱性盐湖烃源岩独特的双峰生油模式推进和补充了陆相生油理论，为新疆北部晚古生代超盆地大规模油气勘探、重新评估世界各地盐湖盆地的油气资源潜力提供了理论依据，揭示了整个油气系统在源岩层序内的主要油气勘探领域。

附：英文原文

Title: Unique bimodal oil generation of alkaline-saline lacustrine source rock: Evidences, model and mechanism of organic-inorganic interactions

Author: Jian CAO, Ruijie ZHANG, Dongming ZHI, Yong TANG, Liuwen XIA, Wenjun HE

Issue&Volume: 2025/04/21

Abstract: The alkaline-saline lacustrine hydrocarbon source rocks of the Fengcheng Formation in the Junggar Basin, China, represent a new end-member type of high-quality terrestrial source rocks. The hydrocarbon generation model for these source rocks remains to be developed, which is a critical scientific issue in the study of terrestrial hydrocarbon generation theory. To fill the knowledge gap, this paper conducts a comprehensive study based on the research idea of biotic-environmental co-evolution and organic-inorganic interactions. We investigate all aspects of hydrocarbon generation by alkaline-saline lacustrine source rocks, including natural profiles, artificial profiles, kinetics, calibration of reservoir oil and gas characteristics, fluid inclusion analysis, as well as relevant geological and geochemical analyses. The hydrocarbon generation model was deeply explored and established in terms of evidences, mechanisms, connotations, and significance. Results show that such source rocks exhibit unique two peaks of hydrocarbon generation, which is dominated by oil rather than gas, with peaks of oil generation in the mature and high-mature stages, which differs from the classical Tissot hydrocarbon-generation model. This is due to the unique sedimentary environment of alkaline lakes, and their biota and inorganic minerals, which result in biotic-environmental and organic-inorganic interactions. The two main organic matter precursors, which are Dunaliella-like algae and cyanobacteria, provided the material for the two peaks of hydrocarbon generation. Alkali minerals affected the hydrocarbon generation process via a saponification reaction, resulting in a more protracted oil-generation window and higher oil-generation yield. The salinity and pH affected the thermal evolution of the organic matter, which retarded the evolution of hydrocarbons. The two stages of uplift during the burial of the source rocks further promoted the two peaks of hydrocarbon generation. Alkaline-saline lacustrine source rocks efficiently generate hydrocarbons, forming unique naphthenic oils and providing a resource foundation for the whole petroleum system. The unique bimodal oil generation of alkaline-saline lacustrine source rock has advanced and supplemented the theory of terrestrial oil generation, and it is the theoretical basis for large-scale oil and gas exploration in the Late Paleozoic super basin of northern Xinjiang, for reevaluating the hydrocarbon resource potential of saline lake basins across the world, and reveals the major hydrocarbon exploration field of the whole petroleum system within source rock sequences.

DOI: 10.1007/s11430-024-1525-0

Source: https://www.sciengine.com/10.1007/s11430-024-1525-0