Organic shale micropore and mesopore structure characterization by ultra-low pressure N2 physisorption: Experimental procedure and interpretation model

  • 邓春林
  • Created: 2016-04-21

Characterizing the micropore and mesopore structure of organic shale is critical for understanding the storage state and flow mechanism of shale gas. In comparison with microscopic observation and radiation detection methods, up to now, N2 physisorption has been widely used for quantitatively analyzing the mesopores in organic shale. Use of this method is rare for micropores. It is well known that the effectiveness of N2 physisorption in pore structure analysis is mostly influenced by both its experimental procedure and the interpretation models. This paper explores the effect of experimental preparation process, including sample size, outgassing temperature, vacuum pump, and equilibrium time threshold, on N2 physisorption. Within, a standard experimental procedure for organic shale sample preparation was recommended. Moreover, a comprehensive validation was performed on the most available interpretation models for characterizing and comparing micropore and mesopore structures. According to the CO2 adsorption results, the HorvatheKawazoe (HK) model worked best for organic shale micropore analysis, especially when carbon and aluminosilicate oxide ion were used as the adsorbents to represent organic matter and inorganic minerals, respectively. The BrunauereEmmetteTeller (BET) and BarretteJoynereHalenda (BJH) models worked well for characterizing mesopores in organic shale, but methods based on density functional theory lost their effectiveness for organic shale due to the lack of a suitable kernel.