Nanopore structure comparison between shale oil and shale gas: examples from the Bakken and Longmaxi Formations

Petroleum Science

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[1] 0000 0004 0375 4078, grid.1032.0, Department of Petroleum Engineering, Curtin University, 6151, Perth, Australia;0000 0004 0644 5828, grid.437806.e, State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Southwest Petroleum University, 610500, Chengdu, China;0000 0004 1936 8163, grid.266862.e, Department of Petroleum Engineering, University of North Dakota, 58202, Grand Forks, ND, USA;

关键词: Shale gas;    Shale oil;    Pore structure;    Gas adsorption;    Pore family;    Multifractal analysis;   

DOI  :  10.1007/s12182-018-0277-3

来源: publisher

【 摘 要 】

In order to analyze and compare the differences in pore structures between shale gas and shale oil formations, a few samples from the Longmaxi and Bakken Formations were collected and studied using X-ray diffraction, LECO TOC measurement, gas adsorption and field-emission scanning electron microscope. The results show that samples from the Bakken Formation have a higher TOC than those from the Longmaxi Formation. The Longmaxi Formation has higher micropore volume and larger micropore surface area and exhibited a smaller average distribution of microsize pores compared to the Bakken Formation. Both formations have similar meso-macropore volume. The Longmaxi Formation has a much larger meso-macropore surface area, which is corresponding to a smaller average meso-macropore size. CO2 adsorption data processing shows that the pore size of the majority of the micropores in the samples from the Longmaxi Formation is less than 1 nm, while the pore size of the most of the micropores in the samples from the Bakken Formation is larger than 1 nm. Both formations have the same number of pore clusters in the 2–20 nm range, but the Bakken Formation has two additional pore size groups with mean pore size diameters larger than 20 nm. Multifractal analysis of pore size distribution curves that was derived from gas adsorption indicates that the samples from the Longmaxi Formation have more significant micropore heterogeneity and less meso-macropore heterogeneity. Abundant micropores as well as meso-macropores exist in the organic matter in the Longmaxi Formation, while the organic matter of the Bakken Formation hosts mainly micropores.

【 授权许可】

CC BY