Abstract
The tight sandstones of the Upper Triassic Xujiahe Formation (T3x) constitute important gas reservoirs in western Sichuan. The Xujiahe sandstones are characterized by low to very low porosity (av. 5.22% and 3.62% for the T3x4 and T3x2 sandstones, respectively), extremely low permeability (av. 0.060 mD and 0.058 mD for the T3x4 and T3x2 sandstones, respectively), strong heterogeneity, micronano pore throat, and poor pore throat sorting. As a result of complex pore structure and the occurrence of fractures, weak correlations exist between petrophysical properties and pore throat size, demonstrating that porosity or pore throat size alone does not serve as a good permeability predictor. Much improved correlations can be obtained between permeability and porosity when pore throat radii are incorporated. Correlations between porosity, permeability, and pore throat radii corresponding to different saturations of mercury were established, showing that the pore throat radius at 20% mercury saturation (R20) is the best permeability predictor. Multivariate regression analysis and artificial neural network (ANN) methods were used to establish permeability prediction models and the unique characteristics of neural networks enable them to be more successful in predicting permeability than the multivariate regression model. In addition, four petrophysical rock types can be identified based on the distributions of R20, each exhibiting distinct petrophysical properties and corresponding to different flow units.
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References
Beard D C and Weyl P K. Influence of texture on porosity and permeability of unconsolidated sand. AAPG Bulletin. 1973. 57: 349–369
Bloch S. Empirical prediction of porosity and permeability in sandstones. AAPG Bulletin. 1991. 75: 1145–1160
Christopher M P, Deborah D S and Charles A D. Permeability estimation in tight gas sandstones and shales using NMR—A new interpretive methodology. Search and Discovery Article. 2010
Coskun S B, Wardlaw N C and Haverslew B. Effects of composition, texture and diagenesis on porosity, permeability, and oil recovery in a sandstone reservoir. Journal of Petroleum Science and Engineering. 1993. 8(4): 279–292
Gu X D and Liu X H. Stratigraphy in Sichuan Basin. Wuhan: China University of GeoSciences Press. 1997 (in Chinese)
Katz A J and Thompson A H. Quantitative prediction of permeability in porous rock. Physical Review B. 1986. 34(11): 8179–8181
Katz A J and Thompson A H. Prediction of rock electrical conductivity from mercury injection measurements. Journal of Geophysical Research. 1987. 92(B1): 599–607
Kolodzie S J. Analysis of pore throat size and use of the Waxman-Smits equation to determine OOIP in Spindle Field, Colorado. Society of Petroleum Engineers, 55th Annual Fall Technical Conference. 1980. Paper SPE-9382
Lü Z X. Evolutionary characteristics of the Upper Triassic reservoir in the Xiaoquan structure in West Sichuan, China. Journal of Chengdu University of Technology (Science and Technology Edition). 2005. 32(1): 22–26 (in Chinese)
Lü Z X and Liu S B. Ultra-tight sandstone diagenesis and a mechanism for the formation of the relatively high-quality reservoir of the Xujiahe group in western Sichuan. Acta Petrologica Sinica. 2009. 25(10): 2373–2383 (in Chinese)
Meng Q R, Wang E and Hu J M. Mesozoic sedimentary evolution of the northwest Sichuan Basin: implication for continued clockwise rotation of the south China block. Geological Society of America Bulletin. 2005. 117(3–4): 396–410
Nelson P H. Pore-throat sizes in sandstones, tight sandstones, and shales. AAPG Bulletin. 2009. 93(3): 329–340
Pittman E D. Relationship of porosity and permeability to various parameters derived from mercury injection-capillary pressure curves for sandstone. AAPG Bulletin. 1992. 76: 191–198
Pittman E D. Estimating pore throat size in sandstones from routine core-analysis data. Search and Discovery Article. 2001
Purcell W R. Capillary pressures-their measurements using mercury and the calculation of permeability therefrom. Trans. AIME. 1949. 186: 39–48
Swanson B F. A simple correlation between permeabilities and mercury capillary pressures. Journal of Petroleum Technology. 1981. 33(12): 2488–2504
Van Brakel J, Modry S and Svata M. Mercury porosimetry: state of the art. Power Technology. 1981. 29: 1–12
Washburn E W. Note on a method of determining the distribution of pore sizes in a porous material. Proceedings of the National Academy of Science. 1921. 7: 115–116
Xiao L and Zhang W. A new method to construct reservoir capillary pressure curves using NMR log data and its application. Applied Geophysics. 2008. 5(2): 92–98
Xiao Z X, Xiao L and Zhang W. A new method for calculating sandstone permeability by using capillary pressure curves. Geophysical Prospecting for Petroleum. 2008. 47(2): 204–207 (in Chinese)
Xu X S, Liu B J, Zhao Y G, et al. Sequence Stratigraphy and Basin-Mountain Transformation in the Western Margin of Upper Yangtze Landmass during the Permian to Triassic. Beijing: Geological Publishing House. 1997 (in Chinese)
Xu Z Y, Zhang X Y, Wu S H, et al. Genesis of low-permeability reservoir bed of Upper Triassic Xujiahe Formation in Xinchang gas field, Western Sichuan Depression. Petroleum Science. 2008. 5(3): 230–237
Zhang J C, Liu L and Song K P. Neural approach for calculating permeability of porous medium. Chinese Physics Letters. 2006. 23: 1009–1011
Zhao Y C, Chen S H and Guo Z H. Application of nuclear magnetic resonance technology to pore structure in tight sandstone: A case from the third member of the Shihezi Formation Upper Paleozoic in the Daniudi gas field, Ordos Basin. Geological Science and Technology Information. 2006. 25(1): 109–112 (in Chinese)
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Ye, S., Lü, Z. & Li, R. Petrophysical and capillary pressure properties of the upper Triassic Xujiahe Formation tight gas sandstones in western Sichuan, China. Pet. Sci. 8, 34–42 (2011). https://doi.org/10.1007/s12182-011-0112-6
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DOI: https://doi.org/10.1007/s12182-011-0112-6