8 Pore Size Distribution and Morphology in the Horn River Shale, Middle and Upper Devonian, Northeastern British Columbia, Canada
8 Pore Size Distribution and Morphology in the Horn River Shale, Middle and Upper Devonian, Northeastern British Columbia, Canada
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发表时间：
2013
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通讯作者：
T. Dong;N. Harris
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作者：
T. Dong;N. Harris
摘要孔隙度和孔径分布是表征页岩气储集能力和流动性的关键属性。在这项研究中的页岩样品从霍恩河形成，场发射扫描电子显微镜（SEM）的氩离子研磨样品，氮吸附和解吸实验，和压汞毛细管压力的图像分析应用到表征孔隙体积，孔隙形态和孔径。氦气孔隙度测量值范围为2.3%至6.6%。从SEM图像分析估计的孔隙率显著较低，表明该方法未能解析由小孔表示的显著孔体积。基于SEM图像分析，大多数观察到的孔是有机物质内的颗粒内孔，无机基质内的孔较少。在黄铁矿framboids，颗粒之间，和周围的颗粒边缘观察到颗粒间孔隙。在一些图像中注意到的微裂缝可能影响气体储存和运输。孔径分布的估计也取决于分析方法。二次电子SEM图像的图像分析表明主要孔径范围为10至40 nm，而氮吸附/脱附等温线（BET）分析表明3至5 nm的小得多的主要孔径范围。汞注射毛细管压力的结果表明，占主导地位的孔喉尺寸范围从3到8 nm，与氮吸附/解吸等温线分析一致。SEM和氮吸附/脱附结果之间的差异也表明，用场发射SEM获得的SEM图像未能解决一类重要的孔。
Abstract Porosity and pore size distributions are key attributes for characterizing shale gas storage capacity and flow in shale. In this study of shale samples from the Horn River Formation, analysis of field emission scanning electron microscopic (SEM) images of argon-ion-milled samples, nitrogen adsorption and desorption experiments, and mercury injection capillary pressure were applied to characterize pore volumes, pore morphology, and pore sizes. Helium porosity measurements range from 2.3 to 6.6%. Porosity estimated from analysis of SEM images was significantly lower, suggesting that this approach fails to resolve a significant pore volume represented by small pores. Based on SEM image analysis, most observed pores were intraparticle pores within organic matter and less commonly within inorganic matrix. Interparticle pores were observed in pyrite framboids, between grains, and surrounding grain rims. Microfractures noted in some images may influence both gas storage and transport. Estimates of pore size distributions also depend on the analytical method. Image analysis of secondary electron SEM images indicated the dominant pore size range is 10 to 40 nm, whereas nitrogen adsorption/desorption isotherm (BET) analysis indicated a much smaller dominant pore size range of 3 to 5 nm. Mercury injection capillary pressure results demonstrated a dominant pore throat size ranging from 3 to 8 nm, consistent with the nitrogen adsorption/desorption isotherm analysis. The discrepancy between SEM and nitrogen adsorption/desorption results also suggests that SEM images obtained with field emission SEM failed to resolve an important class of pores.