四川盆地侏罗系凉高山组不同岩性组合页岩油赋存状态及可动性

Occurrence states and mobility of shale oil in different lithologic assemblages in the Jurassic Lianggaoshan Formation， Sichuan Basin

方锐 蒋裕强 杨长城 邓海波 蒋婵 洪海涛 唐松 谷一凡 朱讯 孙莎莎 蔡光银

Rui FANG Yuqiang JIANG Changcheng YANG Haibo DENG Chan JIANG Haitao HONG Song TANG Yifan GU Xun ZHU Shasha SUN Guangyin CAI

通过系统分析钻井取心资料，将四川盆地侏罗系凉高山组页岩细分为纯页岩型组合、介壳型页岩组合和粉砂型页岩组合等3类5种岩性组合，在此基础上，总结不同岩性组合页岩储层宏观、微观特征差异，识别并评价不同岩性组合页岩油储层流体赋存状态特征及可动性，优选有利岩性组合类型。研究表明：①凉高山组页岩油分为游离油和吸附油，游离油具有易流动油和束缚油2种赋存状态，页岩孔隙中，小孔主要赋存吸附油和束缚油，中孔主要赋存束缚油和易流动油，大孔主要为易流动油；二维核磁共振≥0.2 ms，1≤/<10的区域为易流动油以及束缚油信号，<0.2 ms，10≤/<100的区域则为吸附油信号，并建立了凉高山组不同赋存状态流体二维核磁共振-识别图版；核磁共振孔径转换揭示了凉高山组页岩油游离油孔径下限为60 nm，建立了基于孔径大小和流体赋存状态的页岩油储层孔隙划分方案。②有机质含量、流体流动能力、矿物组成及孔隙结构是凉高山组页岩油赋存及可动性的直接影响因素。③粉砂型页岩组合大孔及微裂缝发育，易流动孔隙占比高，可动油更容易富集；粉砂纹层构造发育不仅能够提供丰富的储集空间，也会提高孔隙连通性，有利于页岩油聚集、赋存及流动，指示了粉砂型页岩组合为凉高山组有利岩性组合类型，其发育层段即为四川盆地凉高山组页岩油勘探开发有利层段。明确粉砂型页岩组合孔-缝配置关系是未来凉高山组页岩油勘探开发取得突破的主要攻关研究方向。

Based on a systematic analysis of the data from well cores， we divide the lithologic assemblages of shales in the Jurassic Lianggaoshan Formation in the Sichuan Basin into pure， shelly， and silty categories， which are further categorized into five types. A summary of differences in the macroscopic and microscopic characteristics of shale reservoirs of different lithologic assemblages is then deduced to identify and evaluate the occurrence states and mobility of fluids in these reservoirs， and determine the optimal lithologic assemblage types. The results indicate that the shale oil in the Lianggaoshan Formation is of free and adsorbed types， with the former occurring as movable and/or irreducible oil. Among shale pores， small pores primarily contain adsorbed and irreducible oil， mesopores largely hold irreducible and movable oil， and macropores mainly contain movable oil. The 2D nuclear magnetic resonance （NMR） analysis reveals that zones with ≥ 0.2 ms and 1 ≤ / < 10 represent the signals of movable and irreducible oil and those with < 0.2 ms and 10 ≤ / < 100 denote the signals of adsorbed oil. This enables the establishment of an identification chart of 2D NMR - spectra for fluids of different occurrence states in the Lianggaoshan Formation. The pore size conversion based on the NMR analysis reveals that pores containing free oil in shales of the formation have a minimum pore size of 60 nm. Accordingly， a classification scheme for pores in the shale oil reservoirs is developed based on pore size and the occurrence state of fluids. Factors directly affecting the occurrence and mobility of shale oil in the Lianggaoshan Formation are identified as organic matter content， fluid flowability， mineral composition， and pore structure. The silty shale assemblage， characterized by well-developed macropores and microfractures and a high proportion of pores containing movable oil， is favorable for the enrichment of movable oil. Besides， its silty laminae provide both substantial reservoir spaces and enhance pore connectivity， which create favorable conditions for the accumulation， occurrence， and flow of shale oil. Therefore， the silty shale assemblage stands as a favorable lithologic assemblage category in the Lianggaoshan Formation， with intervals where this assemblage occurs serving as play fairways for shale oil exploration and exploitation in the Lianggaoshan Formation， Sichuan Basin. Therefore， determining the pore-fracture configuration in the silty shale assemblage is of primary significance in research to achieving breakthroughs in shale oil exploration and exploitation of the Lianggaoshan Formation.

10.11743/ogg20240313