超临界二氧化碳萃取泥页岩中可动油实验研究

Movable oil extraction from shale with supercritical carbon dioxide

  • 摘要: 针对泥页岩基质型页岩油有效开发面临的问题,以渤海湾盆地济阳坳陷沾化凹陷古近系沙河街组沙三下亚段典型含油泥页岩样品为例,开展了地层温度下密闭压裂改造后一定负压和超临界二氧化碳流体在不同压力条件下吞吐萃取可动油实验研究。实验结果揭示:地层温度与一定负压下仅微量轻质组分(< C15)可流动;在相同地层温度与流体压力下,随着超临界二氧化碳流体吞吐作用时间增长,可动油主要组分的碳数呈现增高趋势;随着流体压力的增大,超临界二氧化碳吞吐萃取可动油量显著提高,不仅以游离态赋存的轻质油组分和中质油组分被有效萃取出来,而且部分以束缚态(吸附—互溶态)赋存的重质组分也被萃取出来。超临界二氧化碳技术在提高泥页岩基质型页岩油采收率领域具有广阔的应用前景。

     

    Abstract: Movable oil extraction experiments from the lower part of third member of Paleogene Shahejie Formation (Es3L) in the Zhanhua Sag of Jiyang Depression of Bohai Bay Basin were made to address problems on matrix shale oil exploitation. Various negative pressure and different supercritical carbon dioxide fluid pressures at strata temperature were used after fracturing in a closed system. Only traces of light hydrocarbons (< C15) can flow at strata temperature and negative pressure. The carbon number of the main components of movable oil increases with extraction time with supercritical carbon dioxide under the same strata temperature and fluid pressure, and the contents of movable oil increase with fluid pressure increase. The light and medium weight hydrocarbon components in the free state are extracted effectively and some heavy hydrocarbon components in the bound-state (adsorption and miscible state) are also extracted. It suggests that the technology of supercritical carbon dioxide has a good prospect for improving recovery efficiency of matrix shale oil.

     

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