摘要
为研究四川盆地泸州地区龙马溪组深层页岩储层微观孔隙发育特征，利用扫描电镜、低温N2吸附、低温CO2吸附、核磁共振测试以及X射线衍射、总有机碳质量分数（TOC）和岩石物性测试等手段，对孔隙结构进行全孔径表征。研究结果表明：1）研究区页岩孔隙分为有机质孔、粒间孔、粒内孔和微裂缝，龙马溪组上段和下段的页岩孔隙特征明显不同，孔隙结构更加复杂；2）TOC控制孔隙形态，随着TOC增加，龙马溪组上段的平行板状孔逐渐过渡为下段的狭缝状孔和墨水瓶状孔；3）核磁共振测试的孔径偏大，在表征较大孔隙上效果较好；4）总孔体积主要受介孔控制，孔体积的主要贡献孔径分布在0..5~0.6，2.0~4.0，10.0~30.0 nm，比表面积主要由微孔和介孔贡献，孔径主要分布在0.5~0.7，2.0~4.0 nm，且龙马溪组下段页岩中广泛发育的有机质孔是导致其孔隙总体积和比表面积明显大于上段的主要原因。
Abstract
To investigate the micro pore structure characterization of deep shale reservoir in Luzhou area, Sichuan Basin, the scanning electron microscope, low-temperature N2 adsorption, low-temperature CO2 adsorption, nuclear magnetic resonance (NMR) test, X-ray diffraction, organic carbon content (TOC) and rock physical properties test were employed to describe the full-scale pore size distribution. The results are shown as follows. (1) Shale pores are divided into organic matter pores, intergranular pores, intragranular pores and microfractures. The pore characteristics in upper Longmaxi Formation is distinctly different from the lower part, and the pore structure is more complex. (2) TOC controls the pore morphology. As the TOC increases, the parallel plate-like pores of the upper Longmaxi Formation are gradually transformed into slit-like and inkbottle-like pores of the lower Longmaxi Formation. (3) The pore sizes depicted by NMR are relatively large, indicating a better description effect on larger pores. (4) The total pore volume is mainly controlled by mesopores, the dominated pore sizes are distributed in range of 0.5￣0.6 nm, 2.0￣4.0 nm, and 10.0￣30.0 nm, while the specific surface area is primarily dominated by micropores and mesopores in range of 0.5￣0.7 nm and 2.0￣4.0 nm. Meanwhile, the total pore volume and specific surface area in lower Longmaxi Formation shale are significantly larger than that of upper shale, which are mainly ascribed to the widely developed organic matter pores.
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