Morphological complexity and azimuthal disorder of evolving pore space in low-maturity oil shale during in-situ thermal upgrading and impacts on permeability
(
), Abstract
In-situ thermal upgrading is used to tune the pore system in low-maturity oil shales. We introduce fractal dimension (D), form factor (ff) and stochastic entropy (H) to quantify the heating-induced evolution of pore morphological complexity and azimuthal disorder and develop a model to estimate the impact on seepage capacity via permeability. Experiments are conducted under recreated in-situ temperatures and consider anisotropic properties—both parallel and perpendicular to bedding. Results indicate that azimuthal distribution of pores in the bedding-parallel direction are dispersed, while those in the bedding-perpendicular direction are concentrated. D values indicate that higher temperatures reduce the uniformity of the pore size distribution (PSD) in the bedding-parallel direction but narrow the PSD in the bedding-perpendicular direction. The greater ff (> 0.7) values in the bedding-parallel direction account for a large proportion, while the dominated in the bedding-perpendicular direction locates within 0.2–0.7, for all temperatures. The H value of the bedding-parallel sample remains stable at ~0.925 during heating, but gradually increases from 0.808 at 25 ℃ to 0.879 at 500 ℃ for the bedding-perpendicular sample. Congruent with a mechanistic model, the permeability at 500 ℃ is elevated ~1.83 times (bedding-parallel) and ~6.08 times (bedding-perpendicular) relative to that at 25 ℃—confirming the effectiveness of thermal treatment in potentially enhancing production from low-maturity oil shales.
References
Arganda-Carreras, I., Kaynig, V., Rueden, C., Eliceiri, K.W., Schindelin, J., Cardona, A., Sebastian Seung, H., 2017. Trainable Weka Segmentation: a machine learning tool for microscopy pixel classification. Bioimage informatics 33, 2424–2426. https://doi.org/10.1093/bioinformatics/btx180.
Bahadur, J., Chandra, D., Das, A., Vishal, V., Agrawal, A.K., Sen, D., 2023. Pore anisotropy in shale and its dependence on thermal maturity and organic carbon content: a scanning SAXS study. Int. J. Coal Geol. 273. https://doi.org/10.1016/j.coal.2023.104268.
Bai, F.T., Sun, Y.H., Liu, Y.M., Guo, M.Y., 2017. Evaluation of the porous structure of Huadian oil shale during pyrolysis using multiple approaches. Fuel 187, 1–8. https://doi.org/10.1016/j.fuel.2016.09.012.
Bolotov, A.V., Yuan, C.D., Varfolomeev, M.A., Taura, U.H., Al-Wahaibi, Y.M., Minkhanov, I.F., Derevyanko, V.K., Al-Bahry, S., Joshi, S., Tazeev, A.R., Kadyrov, R.I., Emelianov, D.A., Pu, W.F., Naabi, A., Hasani, M., Al Busaidi, R.S., 2023. In-situ combustion technique for developing fractured low permeable oil shale: Experimental evidence for synthetic oil generation and successful propagation of combustion front. Fuel 344, 127995. https://doi.org/10.1016/j.fuel.2023.127995.
Caniego, F.J., Martín, M.A., San José, F., 2000. Singularity features of pore-size soil distribution: Singularity strength analysis and entropy spectrum. Fractals 9, 305–316. https://doi.org/10.1142/S0218348X0100066X.
Chandra, D., Bakshi, T., Bahadur, J., Hazra, B., Vishal, V., Kumar, S., Sen, D., Singh, T.N., 2023. Pore morphology in thermally-treated shales and its implication on CO2 storage applications: a gas sorption, SEM, and small-angle scattering study. Fuel 331, 125877. https://doi.org/10.1016/j.fuel.2022.125877.
Cox, M.R., Budhu, M., 2008. A practical approach to grain shape quantification. Eng. Geol. 96, 1–16. https://doi.org/10.1016/j.enggeo.2007.05.005.
Dang, W., Nie, H.K., Zhang, J.C., Tang, X., Jiang, S., Wei, X.L., Liu, Y., Wang, F.Q., Li, P., Chen, Z.P., 2022. Pore-scale mechanisms and characterization of light oil storage in shale nanopores: new method and insights. Geosci. Front. 13, 101424. https://doi.org/10.1016/j.gsf.2022.101424.
Dathe, A., Thullner, M., 2005. The relationship between fractal properties of solid matrix and pore space in porous media. Geoderma 129, 279–290. https://doi.org/10.1016/j.geoderma.2005.01.003.
Drouven, M.G., Cafaro, D.C., Grossmann, I.E., 2023. Mathematical programming models for shale oil & gas development: a review and perspective. Comput. Chem. Eng. 177, 108317. https://doi.org/10.1016/j.compchemeng.2023.108317.
Feng, Q.H., Xu, S.Q., Xing, X.D., Zhang, W., Wang, S., 2020. Advances and challenges in shale oil development: a critical review. Advances in Geo-Energy Research 4, 406–418. https://doi.org/10.46690/ager.2020.04.06.
Gou, Q.Y., Xu, S., 2023. The controls of laminae on lacustrine shale oil content in China: a review from generation, retention, and storage. Energies 16, 1987. https://doi.org/10.3390/en16041987.
Han, X., Liu, Q., Jiang, X., 2015. Heat transfer characteristic of oil shale particle during the retorting. Int. J. Heat Mass Tran. 84, 578–583. https://doi.org/10.1016/j.ijheatmasstransfer.2015.01.058.
He, W.Y., Meng, Q.A., Lin, T.F., Wang, R., Liu, X., Ma, S.M., Li, X., Yang, F., Sun, G.X., 2022. Evolution features of in-situ permeability of low-maturity shale with the increasing temperature, Cretaceous Nenjiang Formation, northern Songliao Basin, NE China. Petrol. Explor. Dev. 49, 516–529. https://doi.org/10.1016/S1876-3804(22)60043-0.
Huang, X.D., Yang, D., Kang, Z.Q., 2021. Three-phase segmentation method for organic matter recognition in source rocks via CT images: a case study on oil shale pyrolyzed by steam. Energy & Fuels 35, 10075–10085. https://doi.org/10.1021/acs.energyfuels.1c00917.
Jin, Z.J., Zhu, R.K., Liang, X.P., Shen, Y.Q., 2021. Several issues worthy of attention in current lacustrine shale oil exploration and development. Petrol. Explor. Dev. 48, 1471–1484. https://doi.org/10.1016/S1876-3804(21)60303-8.
Lei, J., Pan, B.Z., Guo, Y.H., Fan, Y.F., Xue, L.F., Deng, S.H., Zhang, L.H., Ruhan, A., 2021. A comprehensive analysis of the pyrolysis effects on oil shale pore structures at multiscale using different measurement methods. Energy 227, 120359. https://doi.org/10.1016/j.energy.2021.120359.
Li, Z.L., Duan, Y.G., Peng, Y., Wei, M.Q., Wang, R., 2020. A laboratory study of microcracks variations in shale induced by temperature change. Fuel 280, 118636. https://doi.org/10.1016/j.fuel.2020.118636.
Lin, M.R., Xi, K.L., Cao, Y.C., Zhu, R.K., Niu, X.B., Xin, H.G., Ma, W.J., 2023. Cyclicity related to solar activity in lacustrine organic-rich shales and their significance to shale-oil reservoir formation. Geosci. Front. 14, 101586. https://doi.org/10.1016/j.gsf.2023.101586.
Lin, T., Liu, X., Zhang, J., Bai, Y., Liu, J., Zhang, Y., Zhao, Y., Cheng, X., Lv, J., Yang, H., 2021. Characterization of multi-component and multi-phase fluids in the Upper Cretaceous oil shale from the Songliao Basin (NE China) using T1–T2 NMR correlation maps. Petrol. Sci. Technol. 39, 1060–1070. https://doi.org/10.1080/10916466.2021.1990318.
Liu, C., Shi, B., Zhou, J., Tang, C.S., 2011. Quantification and characterization of microporosity by image processing, geometric measurement and statistical methods: Application on SEM images of clay materials. Appl. Clay Sci. 54, 97–106. https://doi.org/10.1016/j.clay.2011.07.022.
Liu, F., Zhong, X., Liu, Z., Liang, S., Gao, Y., Wang, S., 2021. Experimental study on dynamic elastic modulus and damping ratio of undisturbed loess based on microstructure. J. Seismol. Res. 44, 105–112 (in Chinese with English abstract).
Liu, J., Yao, Y., Liu, D., Cai, Y., Cai, J., 2018. Comparison of pore fractal characteristics between marine and continental shales. Fractals 26, 1840016. https://doi.org/10.1142/s0218348x18400169.
Liu, J., Bai, X., Elsworth, D., 2024. Evolution of pore systems in low-maturity oil shales during thermal upgrading –Quantified by dynamic SEM and machine learning. Petrol. Sci. https://doi.org/10.1016/j.petsci.2023.1012.1021.
Lormand, C., Zellmer, G.F., Németh, K., Kilgour, G., Mead, S., Palmer, A.S., Sakamoto, N., Yurimoto, H., Moebis, A., 2018. Weka trainable segmentation plugin in ImageJ: a semi-automatic tool applied to crystal size distributions of microlites in volcanic rocks. Microsc. Microanal. 24, 667–675. https://doi.org/10.1017/S1431927618015428.
Luo, Q.Y., Zhang, L., Zhong, N.N., Wu, J., Goodarzi, F., Sanei, H., Skovsted, C.B., Suchy, V., Li, M.J., Ye, X.Z., Cao, W.X., Liu, A.J., Min, X., Pan, Y.Y., Yao, L.P., Wu, J., 2021. Thermal evolution behavior of the organic matter and a ray of light on the origin of vitrinite-like maceral in the Mesoproterozoic and Lower Cambrian black shales: insights from artificial maturation. Int. J. Coal Geol. 244, 103813. https://doi.org/10.1016/j.coal.2021.103813.
Luo, Z.K., Lin, T.F., Liu, X., Ma, S.M., Li, X., Yang, F., He, B., Liu, J., Zhang, Y., Xie, L.Z., 2023. High-temperature-induced pore system evolution of immature shale with different total organic carbon contents. ACS Omega 8, 12773–12786. https://doi.org/10.1021/acsomega.2c07990.
Qi, J.F., Sui, W.H., Zhang, C.L., Xu, J.S., 2014. Calculation and analysis of the porosity and fractal dimension of red stratum sandstone based on SEM images processing. J. Eng. Geol. 22, 339–345 (In Chinese with English abstract).
Sezer, G.I., Kambiz, R., Bekir, K., Goktepe, A.B., Sezer, A., 2008. Image analysis of sulfate attack on hardened cement paste. Mater. Des. 29, 224–231. https://doi.org/10.1016/j.matdes.2006.12.006.
Shi, B., Wang, B.J., Jiang, H.T., 1996. Quantitative assessment of changes of microstructure for clayey soil in the process of compaction. Chin. J. Geotech. Eng. 18, 57–62 (In Chinese with English abstract).
Soroushian, P., Elzafraney, M., 2005. Morphological operations, planar mathematical formulations, and stereological interpretations for automated image analysis of concrete microstructure. Cement Concr. Compos. 27, 823–833. https://doi.org/10.1016/j.cemconcomp.2004.07.008.
Su, P.H., Xia, Z.H., Qu, L.C., Yu, W., Wang, P., Li, D.W., Kong, X.W., 2018. Fractal characteristics of low-permeability gas sandstones based on a new model for mercury intrusion porosimetry. J. Nat. Gas Sci. Eng. 60, 246–255. https://doi.org/10.1016/j.jngse.2018.10.008.
Syed, F.I., Dahaghi, A.K., Muther, T., 2022. Laboratory to field scale assessment for EOR applicability in tight oil reservoirs. Petrol. Sci. 19, 2131–2149. https://doi.org/10.1016/j.petsci.2022.04.014.
Thilagashanthi, T., Gunasekaran, K., Satyanarayanan, K.S., Klemes, J.J., 2021. Microstructural pore analysis using SEM and ImageJ on the absorption of treated coconut shell aggregate. J. Clean. Prod. 324, 129217. https://doi.org/10.1016/j.jclepro.2021.129217.
Tietz, C., Schuler, S., Speck, T., Seifert, U., Wrachtrup, J., 2006. Measurement of stochastic entropy production. Phys. Rev. Lett. 97, 050602. https://doi.org/10.1103/PhysRevLett.97.050602.
Vatter, M.H., Van Vactor, S.A., Coburn, T.C., 2022. Price responsiveness of shale oil: a Bakken case study. Natural Resources Research 31, 713–734. https://doi.org/10.1007/s11053-021-09972-9.
Wang, G.Y., Yang, D., Kang, Z.Q., Zhao, J., Lv, Y.Q., 2019. Numerical investigation of the in situ oil shale pyrolysis process by superheated steam considering the anisotropy of the thermal, hydraulic, and mechanical characteristics of oil shale. Energy & Fuels 33, 12236–12250. https://doi.org/10.1021/acs.energyfuels.9b02883.
Wang, G.P., Jin, Z.J., Liu, G.X., Wang, R.Y., Zhao, G., Tang, X., Liu, K.Q., Zhang, Q., 2023a. Pore system of the multiple lithofacies reservoirs in unconventional lacustrine shale oil formation. Int. J. Coal Geol. 273, 104270. https://doi.org/10.1016/j.coal.2023.104270.
Wang, J., Xie, H.P., Matthai, S.K., Hu, J.J., Li, C.B., 2023b. The role of natural fracture activation in hydraulic fracturing for deep unconventional geo-energy reservoir stimulation. Petrol. Sci. 20, 2141–2164. https://doi.org/10.1016/j.petsci.2023.01.007.
Wang, X.N., Li, J.R., Jiang, W.Q., Zhang, H., Feng, Y.L., Yang, Z., 2022. Characteristics, current exploration practices, and prospects of continental shale oil in China. Advances in Geo-Energy Research 6, 454–459. https://doi.org/10.46690/ager.2022.06.02.
Wang, Z.J., Yao, J., Sun, H., Yan, X., Yang, Y.F., 2021. A multi-continuum model for simulating in-situ conversion process in low-medium maturity shale oil reservoir. Advances in Geo-Energy Research 5, 456–464. https://doi.org/10.46690/ager.2021.04.10.
Wehrl, A., 1978. General properties of entropy. Rev. Mod. Phys. 50, 221–260. https://doi.org/10.1103/RevModPhys.50.221.
Wei, Z.J., Sheng, J.J., 2022. Study of thermally-induced enhancement in nanopores, microcracks, porosity and permeability of rocks from different ultra-low permeability reservoirs. J. Petrol. Sci. Eng. 209, 109896. https://doi.org/10.1016/j.petrol.2021.109896.
Wu, J.S., Yu, B.M., 2007. A fractal resistance model for flow through porous media. Int. J. Heat Mass Tran. 50, 3925–3932. https://doi.org/10.1016/j.ijheatmasstransfer.2007.02.009.
Wu, J.S., Yu, B.M., Yun, M.J., 2008. A resistance model for flow through porous media. Transport Porous Media 71, 331–343. https://doi.org/10.1007/s11242-007-9129-0.
Wu, J.S., Zhang, C.Y., Yu, B.M., Yin, S.X., Xing, M., Chen, X.X., Lian, H.Q., Yi, S.H., 2022. Fractal characteristics of low-permeability sandstone reservoirs. Fractals 30, 2250075. https://doi.org/10.1142/S0218348x2250075x.
Wu, K., Ni, W., Liu, H., Yuan, Z., Zhu, Q., Shi, B., 2016. Research on the relationships between the strength properties of compacted loess and microstructure changes. Hydrogeol. Eng. Geol. 43, 62-69 (In Chinese with English abstract).
Xu, Y., Lun, Z.M., Pan, Z.J., Wang, H.T., Zhou, X., Zhao, C.P., Zhang, D.F., 2022. Occurrence space and state of shale oil: a review. J. Petrol. Sci. Eng. 211, 110183. https://doi.org/10.1016/j.petrol.2022.110183.
Yan, G., Xu, Y.H., Xu, W.L., Bai, B., Bai, Y., Fan, Y.P., Li, S.S., Zhong, M., Liu, Y., Xu, Z.Y., 2023. Shale oil resource evaluation with an improved understanding of free hydrocarbons: insights from three-step hydrocarbon thermal desorption. Geosci. Front. 14, 101677. https://doi.org/10.1016/j.gsf.2023.101677.
Yang, L.S., Yang, D., Zhao, J., Liu, Z.H., Kang, Z.Q., 2016. Changes of oil shale pore structure and permeability at different temperatures. Oil Shale 33, 101–110. https://doi.org/10.3176/oil.2016.2.01.
Yao, Y.B., Liu, D.M., Tang, D.Z., Tang, S.H., Huang, W.H., 2008. Fractal characterization of adsorption-pores of coals from North China: an investigation on CH4 adsorption capacity of coals. Int. J. Coal Geol. 73, 27–42. https://doi.org/10.1016/j.coal.2007.07.003.
Zhang, Y., Feng, D., Wan, S., Wang, Z., Yu, R., Zhang, P., Zhang, X., Feng, Y., 2023. Enhancing performance in organic solid structures and heat transfer with single annealing process and variable rates. Int. J. Heat Mass Tran. 213, 124306. https://doi.org/10.1016/j.ijheatmasstransfer.2023.124306.
Zhao, J., Wang, L., Liu, S.M., Kang, Z.Q., Yang, D., Zhao, Y.S., 2022. Numerical simulation and thermo-hydro-mechanical coupling model of in situ mining of low-mature organic-rich shale by convection heating. Advances in Geo-Energy Research 6, 502–514. https://doi.org/10.46690/ager.2022.06.07.
Zhao, J., Yang, D., Kang, Z.Q., Feng, Z.C., 2012. A micro-CT study of changes in the internal structure of Daqing and Yan'an oil shales at high temperatures. Oil Shale 29, 357–367. https://doi.org/10.3176/oil.2012.4.06.
Zheng, S.J., Yao, Y.B., Liu, D.M., Cai, Y.D., Liu, Y., 2018. Characterizations of full-scale pore size distribution, porosity and permeability of coals: a novel methodology by nuclear magnetic resonance and fractal analysis theory. Int. J. Coal Geol. 196, 148–158. https://doi.org/10.1016/j.coal.2018.07.008.
Zhou, H., Zeng, S., Zhan, L., Xu, G., Qian, Y., 2018. Modelling and analysis of oil shale refinery process with the indirectly heated moving bed. Carbon Resources Conversion 1, 260–265. https://doi.org/10.1016/B978-0-444-64241-7.50240-8.
Zhou, J.P., Yang, K., Zhou, L., Jiang, Y.D., Xian, X.F., Zhang, C.P., Tian, S.F., Fan, M.L., Lu, Z.H., 2021. Microstructure and mechanical properties alterations in shale treated via CO2/CO2-water exposure. J. Petrol. Sci. Eng. 196, 108088. https://doi.org/10.1016/j.petrol.2020.108088.
Zhou, J.P., Tian, S.F., Xian, X.F., Zheng, Y., Yang, K., Liu, J.F., 2022. Comprehensive review of property alterations induced by CO2-shale interaction: Implications for CO2 sequestration in shale. Energy & Fuels 36, 8066–8080. https://doi.org/10.1021/acs.energyfuels.2c01542.
Zhu, J.Y., Yang, Z.Z., Li, X.G., Wang, N.L., Jia, M., 2018. Evaluation of different microwave heating parameters on the pore structure of oil shale samples. Energy Sci. Eng. 6, 797–809. https://doi.org/10.1002/ese3.253.
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