不同赋存状态页岩油定量表征技术与应用研究

摘要

页岩中滞留油存在着多种赋存形式，其中只有游离油才是天然弹性能量开采方式下页岩油产能的有效贡献者。但是，如何对页岩中游离油与吸附油含量进行定量表征以及如何明确它们与周缘介质的相互关系，目前并没有现成的研究方法。该文通过对现有Rock⁃Eval热解和热解色谱方法进行改进，结合样品溶剂抽提前后热解对比实验和不同类型样品的综合分析，建立了不同赋存状态页岩油热释法定量表征方法。利用新建立的方法对济阳坳陷页岩油专探井岩心样品进行了实验分析，发现页岩吸附油含量与有机质丰度成正比，而干酪根吸附—互溶能力随热成熟度增加而降低；同时，页岩体系内游离油／吸附油比值与有机碳含量存在负相关关系，表明干酪根不是液态游离烃赋存的主要场所。因此，建立的方法可以作为页岩油赋存机理研究和页岩含油性快速评价的实用手段。%Crude oils in shale systems exist in different modes, where only free oil could be a potential contributor to shale oil production. However, there is a general lack of analytical methods for quantitative characterization of free and adsorbed oils in organic⁃rich shale, and little is known of the interrelationships among different states of oils and porous media in shale. A modified Rock⁃Eval and pyrolysis⁃gas chromatographic method was established to quantify different modes of shale oil occurrence in various geological samples. In combination with solvent extraction, this tech⁃nique was applied to analyze continuous shale core samples collected from exploration wells in the Jiyang Depression, Bohai Bay Basin, East China. The results showed a positive correlation between adsorbed oil content and total organic carbon abundance, and a pronounced decrease in the kerogen miscible oil content with increasing thermal maturity. On the other hand, the free/adsorbed oil ratio decreases with increasing TOC in a shale system, suggesting that free oil is associated mainly with inorganic mineral matrix and/or fractures. The study provides a rapid technique for the characterization of shale oil occurrence and the quantitative evaluation of shale oil resources.