Key Laboratory of Coalbed Methane Resources and Accumulation Process, Ministry of Education, China University of Mining and Technology, Jiangsu, Xuzhou 221008, China.
School of Resources and Earth Geosciences, China University of Mining and Technology, Jiangsu, Xuzhou 221116, China.
J Nanosci Nanotechnol. 2021 Jan 1;21(1):343-353. doi: 10.1166/jnn.2021.18721.
Pore structure and fractal dimensions can characterize the adsorption, desorption and seepage characteristics of shale gas reservoirs. In this study, pore structure, fractal characteristics and influencing factors were studied of the Longmaxi formation shale gas reservoir in southeastern Chongqing, China. Scanning electron microscopy was used to describe the characteristics of various reservoirs. High pressure mercury intrusion and low temperature liquid N₂ and CO₂ adsorption experiments were used to obtain pore structure parameters. model, FHH model and Menger sponge model were selected to calculate the micropore, mesopore and macropore fractal dimensions, respectively. The results show that organic matter pores, inter-granular pores, intra-granular pores and micro-fractures are developed within the shale, and the pore morphology is mostly ink pores and parallel plate pores with aperture essentially in the 1-2 nm and 2-50 nm ranges. Moreover, macropores are the most complex in these samples, with mesopores being less complex than macropores, and the micropores being the simplest. (micropore fractal dimension) ranges from 2.31 to 2.50, ₂ (mesopore fractal dimension) ranges from 2.74 to 2.83, ₃ (macropore fractal dimension) ranges from 2.87 to 2.95, and (comprehensive fractal dimension) ranges from 2.69 to 2.83 of fractal characteristics. and ₂ are mainly controlled by TOC content, while ₃ and are mainly controlled by brittle and clay mineral content. These results may be helpful for exploration and the development of shale gas in southeastern Chongqing, China.
孔隙结构和分形维数可以表征页岩气储层的吸附、解吸和渗流特征。本研究以中国重庆东南部龙马溪组页岩气储层为例，对其孔隙结构、分形特征及影响因素进行了研究。采用扫描电镜描述了各种储层的特征。利用高压压汞、低温液体 N₂ 和 CO₂ 吸附实验获得了孔隙结构参数。分别采用 模型、FHH 模型和 Menger 海绵模型计算了微孔、中孔和大孔的分形维数。结果表明，页岩中发育有机质孔、粒间孔、粒内孔和微裂缝，孔隙形态多为墨水瓶状和平行板状，孔径主要在 1-2nm 和 2-50nm 范围内。此外，这些样品中大孔最复杂，中孔比大孔稍简单，微孔最简单。页岩气储层的分形特征参数中， (微孔分形维数)在 2.31-2.50 之间， ₂ (中孔分形维数)在 2.74-2.83 之间， ₃ (大孔分形维数)在 2.87-2.95 之间， (综合分形维数)在 2.69-2.83 之间。 ₂主要受 TOC 含量控制， ₃和 主要受脆性矿物和粘土矿物含量控制。这些结果可能有助于中国重庆东南部地区的页岩气勘探和开发。
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