To address the controlling factors of nanopore volume in mature shales, Eocene Es3lower shales buried in different depths from the Zhanhua sag with 0.70％-0.93％Ro were collected and treated to remove organic matter (OM), then both the original and treated shales were performed by experiments of pyrolysis, X-ray diffraction (XRD) and low temperature N2 adsorption. Results show that the nanopore volume of mature shale is positively correlated with TOC, and the changing rate of TOC after OM removal is also positively correlated with the changing rate of nanopore volume. The content of removed OM corresponds to the change of nanopore volume. Moreover, the pore volume is positively correlated with the abundance of mixed illite/smetcite, illite and quartz, but is negatively correlated with the abundance calcite. Combined with previous works, it can be concluded that the nanopores in these mature shales are mainly mineral pores and marginal pores between OM and minerals. Mineral pores are present in mixed illite/smetcite, illite and quartz, and their development is hindered by calcite. Nanopores in shale are the primary occurrence sites for shale oil and gas, and pore volume is a quantization parameter for shale pore space and is significant to estimate the content of shale oil and gas and assess the reserves. By understanding the controlling factors of nanopore volume in mature shales in the Zhanhua sag, we can improve our knowledge of the reservoir space of shale oil and gas in oil-window. This provides references for shale oil and gas exploration and exploitation.%选取沾化凹陷始新世沙三下亚段(Es3下)不同埋深的成熟泥页岩(0.70％～0.93％Ro),并进行去有机质处理,通过对原样和处理样进行热解、XRD和低温氮气吸附法检测分析,以探讨成熟泥页岩纳米孔隙体积的影响因素.结果表明,成熟泥页岩纳米孔隙体积与TOC显示正相关性;去有机质后,有机质变化率和孔隙体积变化率呈正相关性,且去除的有机质含量亦与孔隙体积变化值呈现对应性;孔隙体积与伊/蒙间层、伊利石和石英呈正相关,与方解石负相关.结合已有研究成果,文章认为,成熟泥页岩的纳米孔隙主要为矿物基质孔和有机质-矿物边缘孔,矿物孔主要由伊/蒙间层、伊利石和石英贡献,方解石阻滞矿物孔隙的发育.泥页岩纳米孔隙是页岩油气赋存的主要储集空间,孔隙体积是泥页岩孔隙空间的一个量化参数,其对页岩油气含量的计算以及储量评估意义重大,弄清沾化凹陷沙三下亚段成熟泥页岩纳米孔隙体积的影响因素,可进一步认识处于生油窗的页岩油气的储集空间,为页岩油气的勘探和开发提供依据.
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