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泥页岩中的孔隙以纳米级孔隙为主,其孔径分布特征对页岩气的保存与开发具有重要影响。以渝东南地区渝参7井下志留统及上奥陶统页岩为例,开展了77.4K下N2和273.15K下CO2吸附实验,利用修正的BET方程、DFT方法、Stoeckli方法等分析手段,探讨了泥页岩孔结构的组成特征及孔径分布的表征方法,初步评价了页岩中微孔、介孔和宏孔的分布特征。结果表明:1渝参7井下志留统和上奥陶统页岩中的微孔、介孔、宏孔均较发育,其相对比例大致相同;2页岩中微孔孔径的均值主要集中在1.26nm处;3基于CO2吸附的Stoeckli方法得到的微孔分布曲线与基于N2吸附的DFT介孔及部分微孔孔径分布曲线在2nm处可较好地衔接,说明联合利用N2和CO2吸附数据可获取页岩中微孔、介孔和部分大孔的连续孔径分布模式。
The pores in shale are dominated by nano-scale pores, and their pore size distribution has an important influence on the preservation and development of shale gas. Taking the Silurian and Upper Ordovician shale in Yushen 7 well in southeastern Chongqing as an example, the CO2 adsorption experiments at 77.4K under N2 and 273.15K were carried out. By means of the modified BET equation, DFT method and Stoeckli method, The compositional characteristics of pore structure and the characterization of pore size distribution are discussed. The distribution characteristics of micropores, mesopores and macropores in shale are preliminarily evaluated. The results show that the micropores, mesopores and macropores in the Silurian and Upper Ordovician shales in the Yuzhen-7 well are relatively developed and their relative proportions are approximately the same. The mean values of the micropores in the shale are mainly in the 1.26 nm. 3 The pore distribution curves obtained by Stoeckli method based on CO2 adsorption and DFT mesopores and some micropore pore size distribution curves based on N2 adsorption can be well connected at 2 nm, indicating that the combined use of N2 and CO2 adsorption data Obtain the continuous pore size distribution pattern of micropores, mesopores and some macropores in shale.