Abstract The porosity system in shale, which is a combination of organic-hosted pore and inorganic pore, plays a pivotal role in adsorbing methane for gas shale reservoir. In order to identify the porosity system with different properties and to give a quantitative characterization of pore structure for each individual porosity system, the dual liquid NMR method was conducted on six shale samples from the Lower Silurian Longmaxi Formation in the Southern Sichuan Basin. In shale reservoir, hydrophilic pore and oleophilic pore are respectively related to hydrophilic minerals and oleophilic organic matter. The NMR method detected the signal of water penetrating the water-wetting porosity system when saturated with water, which can reflect the pore size distribution (PSD) of hydrophilic porosity. The PSD of oleophilic pore can also be reflected when saturated with kerosene, vice versa. Generally, the NMR T2 spectra of sample saturated with DI water and kerosene, T2_water and T2_kerosene exhibit bimodal pattern, a dominant peak with a relaxation time range of 0.1-10 ms and a minor peak with a relaxation time ranging 10-100 ms. Generally, higher TOC content corresponds to large amounts of cumulative organic nanoscale pore. The organic-rich shale shows high content of organic-hosted pores and large amounts of inorganic pores which are validated by plane porosity statistics from the observation of SEM photographs. By correlating the two pore structure characterizing methods, the relaxivity of shale can be calculated to be 0.055-0.092 μm/ms when saturated with water. The quantitative estimation of organic-hosted porosity system and inorganic porosity system in the shale will provide a pivotal basis for elucidating gas occurrence states in shale.

中文翻译：

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四川盆地南部志留系高成熟海相页岩孔隙系统研究

摘要 页岩孔隙系统是有机赋存孔隙和无机孔隙的结合体，在页岩气藏吸附甲烷方面起着举足轻重的作用。为了识别具有不同性质的孔隙系统并定量表征每个孔隙系统的孔隙结构，对四川盆地南部下志留统龙马溪组的 6 个页岩样品进行了双液相核磁共振方法。在页岩储层中，亲水孔隙和亲油孔隙分别与亲水矿物和亲油有机质有关。核磁共振法检测到水饱和时水渗入润湿孔隙系统的信号，可以反映亲水孔隙的孔径分布（PSD）。当用煤油饱和时，也可以反映亲油孔的 PSD，反之亦然。一般来说，用去离子水和煤油、T2_水和T2_煤油饱和的样品的NMR T2谱表现出双峰模式，主峰的弛豫时间范围为0.1-10 ms，次峰的弛豫时间范围为10-100 ms。通常，较高的 TOC 含量对应于大量累积的有机纳米级孔。富有机质页岩显示出高含量的有机质孔隙和大量无机孔隙，通过扫描电镜照片观察得到的平面孔隙度统计数据证实了这一点。将两种孔隙结构表征方法相关联，计算出含水饱和时页岩的弛豫度为0.055-0.092 μm/ms。