Pore evolution characteristics of Chinese marine shale in the thermal simulation experiment and the enlightenment for gas shale evaluation in South China
- 6 Downloads
Although there are many similarities between the shale of Cambrian Qiongzhusi Formation and Ordovician Wufeng Formation–Silurian Longmaxi Formation in South China, including total organic carbon content (TOC) and thickness, the drilling results of shale gas exploration are very different. One of the reasons is the difference of the nano-pores number developed in organic matter between them. In order to reveal the causes, the black shale of Upper Proterozoic Xiamaling Formation in North China, which is similar to the marine source rock in Sichuan basin, was selected for the thermal simulation experiment, and the pore size and volume of the samples before and after the experiment were acquired by scanning electron microscopy (SEM) and nitrogen adsorption isotherm measurement. Through the SEM photographs, we found that the sizes of the organic pores in algae, dispersed organic matter and organic matter associated with clay minerals get bigger with the increasing maturity. The total pore volume, micro-pore volume and meso-pore volume of the shale acquired by nitrogen adsorption isotherm measurement increase with the increasing maturity, too. However, under the overburden pressure, micro-pore volume decreases at high maturity stage, indicating the pores in organic matter might be compressed. It is considered that the pore volume in organic matter of the shale of Qiongzhusi Formation might be compacted under greater confining pressure, which may be the reason why the pore structures of the two sets of marine shale in South China are different.
Key wordsmarine shale thermal simulation experiment organic pore evolution South China
Unable to display preview. Download preview PDF.
- Cander, H., 2012, Sweet spots in shale gas and liquids plays: prediction of fluid composition and reservoir pressure. Search and Discovery, 40936, 29 p. https://doi.org/www.searchanddiscovery.com/documents/2012/40936cander/ndx_cander.pdf Google Scholar
- Katsube, T.J., 1992, Statistical analysis of poresize distribution data of tight shales from the Scotian Shelf. Geological Survey of Canada, 365–372.Google Scholar
- Liang, F., Bai, W., Zou, C., Wang, H., Wu, J., Ma, C., Zhang, Q., Guo, W., Sun, S., Zhu, Y., Cui, H., and Liu, D., 2016, Shale gas enrichment pattern and exploration significance of Well WuXi-2 in northeast Chongqing, NE Sichuan Basin. Petroleum Exploration and Development, 43, 386–394.CrossRefGoogle Scholar
- Liang, F., Zhu, Y., Ma, C., Zhou, H., Wang, H., Bai, W., Zhang, Q., and Cui, H., 2015, Sedimentary distribution and reservoir characteristics of shale gas reservoir of Niutitang Formation in Northwestern Hunan. Journal of China Coal Society, 40, 2884–2892.Google Scholar
- Ma, M., Li, W., and Liu, Y., 2005, Pore structure characteristics analysis of the oilfield in north Melut Basin, Sudan. Petroleum Exploration and Development, 32, 121–124.Google Scholar
- Pfeifer, P. and Avnir, D., 1983, Chemistry in noninteger dimensions between two and three. I. Fractal theory of heterogeneous surfaces. The Journal of Chemical Physics, 79, 3558–3565.Google Scholar
- Wang, F., Guan, J., Feng, W., and Bao, L., 2013, Evolution of overmature marine shale porosity and implication to the free gas volume. Petroleum Exploration and Development, 40, 764–768.Google Scholar