Abstract
We present a pore network model to determine the permeability of shale gas matrix. Contrary to the conventional reservoirs, where permeability is only a function of topology and morphology of the pores, the permeability in shale depends on pressure as well. In addition to traditional viscous flow of Hagen–Poiseuille or Darcy type, we included slip flow and Knudsen diffusion in our network model to simulate gas flow in shale systems that contain pores on both micrometer and nanometer scales. This is the first network model in 3D that combines pores with nanometer and micrometer sizes with different flow physics mechanisms on both scales. Our results showed that estimated apparent permeability is significantly higher when the additional physical phenomena are considered, especially at lower pressures and in networks where nanopores dominate. We performed sensitivity analyses on three different network models with equal porosity; constant cross-section model (CCM), enlarged cross-section model (ECM) and shrunk length model (SLM). For the porous systems with variable pore sizes, the apparent permeability is highly dependent on the fraction of nanopores and the pores’ connectivity. The overall permeability in each model decreased as the fraction of nanopores increased.
Similar content being viewed by others
Abbreviations
- \(A\) :
-
Cross-sectional area, \(\text{ m }^{2}\)
- \(f\) :
-
Nanopore fraction, dimensionless
- \(F\) :
-
Theoretical dimensionless coefficient
- \(J\) :
-
Mass flux,\(\text{ kg/m }^{2}\)/s
- \(K\) :
-
Permeability, \(\text{ m }^{2}\)
- \(L\) :
-
Pore length, m
- \(M\) :
-
Molar mass, kg/kmol
- \(p\) :
-
Pressure, Pa
- \(q\) :
-
Flow rate, m\(^{3}\)/s
- \(r\) :
-
Pore radius, m
- \(R\) :
-
Gas constant, J/mol/K
- \(t\) :
-
Time, s
- \(T\) :
-
Temperature, K
- \(u\) :
-
Velocity, m/s
- \(w\) :
-
Relaxation factor
- \(\alpha \) :
-
Tangential momentum accommodation coefficient, dimensionless
- \(\mu \) :
-
Viscosity, Pa.s
- \(\rho \) :
-
Density, kg/m\(^{3}\)
- \(\varphi \) :
-
Porosity, fraction
- app :
-
Apparent
- avg :
-
Average
- \(i,j\) :
-
Pore identity number
- \(ij\) :
-
Throat identity number (throat connecting pore \(i\) and pore \(j\))
- D :
-
Darcy (referring to Darcy permeability)
References
Ambrose, R.J., Hartman, R.C., Diaz-Campos, M., Akkutlu, I.Y., Sondergeld, C.H.: Shale gas-in-place calculations. Part I. New pore-scale considerations. SPE J. 17(1), 219–229 (2012)
Bauer, D., Youssef, S., Fleury, M., Bekri, S., Rosenberg, E., Vizika, O.: Improving the Estimations of Petrophysical Transport Behavior of Carbonate Rocks Using a Dual Pore Network Approach Combined with Computed Microtomography. Transp. Porous Media 94(2), 505–524 (2012)
Blunt, M.J.: Flow in porous media—pore-network models and multiphase flow. Curr. Opin. Colloid Interface Sci. 6(3), 197–207 (2001). doi:10.1016/S1359-0294(01)00084-X
Brace, W.F., Walsh, J.B., Frangos, W.T.: Permeability of granite under high pressure. J. Geophys. Res. 73, 2225 (1968)
Civan, F., Rai, C.S., Sondergeld, C.H.: SPE Shale permeability determined by simultaneous analysis of multiple pressure-pulse measurements obtained under different conditions. SPE paper 144253 presented at SPE North American Unconventional Gas Conference and Exhibition, The Woodlands, Texas (2011)
Cui, X., Bustin, A.M.M., Bustin, R.M.: Measurements of gas permeability and diffusivity of tight reservoir rocks: different approaches and their applications. Geofluids 9, 209–223 (2009)
Curtis, M.E., Ambrose, R.J., Sondergeld, C.H., Rai, C.S.: Investigation of the relationship between organic porosity and thermal maturity in the Marcellus Shale. SPE paper 144370 presented at SPE North American Unconventional Gas Conference and Exhibition, The Woodlands (2011)
Dewers, T., Heath, J., Ewy, R., Duranti, L.: Three-dimensional pore networks and transport properties of a shale gas formation determined from focused ion beam serial imaging. Int. J. Oil Gas Coal Technol. 5(2/3), 229–248 (2012)
Dicker A.I., Smits R.M.: A practical approach for determining permeability from laboratory pressure-pulse decay measurements. SPE Paper 17578 Presented at the SPE International Meeting in Petroleum Engineering, 1–4 November, Tianjin (1988)
Fatt, I.: The network model of porous media. I. Capillary pressure characteristics. Trans AIME 207, 144–159 (1956a)
Fatt, I.: The network model of porous media. II. Dynamic properties of a single size tube network. Trans AIME 207, 160–163 (1956b)
Fatt, I.: The network model of porous media. III. Dynamic properties of networks with tube radius distribution. Trans AIME 207, 164–181 (1956c)
Freeman, C.A., Moridis, G.J., Blasingame, T.A.: A numerical study of microscale flow behavior in tight gas and shale gas reservoir systems. Transp. Porous Media 90, 253–268 (2011). doi:10.1007/s11242-011-9761-6
Javadpour, F., Fisher, D., Unsworth, M.: Nano-scale gas flow in shale sediments. J. Can. Pet. Technol. 46(10), 55–61 (2007)
Javadpour, F.: Nanopores and apparent permeability of gas flow in Mudrocks (shales and siltstone). J. Can. Pet. Technol. 48, 16–21 (2009)
Joekar-Niasar, V., Hassanizadeh, S.M.: Analysis of fundamentals of two-phase flow in porous media using dynamic pore-network models: a review. Crit. Rev. Environ. Sci. Technol. (2012). doi:10.1080/10643389.2011.574101
Karpyn, Z.T., Piri, M.: Prediction of fluid occupancy in fractures using network modeling and X-ray microtomography. I: data conditioning and model description. Phys Rev E 76(1), 016315 (2007)
Kuila, U., Prasad, M., Kazemi, H.: Application of Knudsen flow in modeling gas-flow in shale reservoirs. SPG extended abstract available from http://www.spgindia.org/paper/sopt/tmp/Kuila_SPG_abstract.docx (2013). Accessed 18 Jan 2013
Levitz, P.: Knudsen diffusion and excitation transfer in random porous media. J. Phys. Chem. 97(15), 3813–3818 (1993)
Loucks, R.G., Reed, R.M., Ruppel, S.C., Jarvie, D.M.: Morphology, genesis, and distribution of nanometer-scale pores in siliceous mudstones of the Mississippian Barnett Shale. J. Sediment. Res. 79, 848–861 (2009)
Loucks, R., Reed, R., Ruppel, S.C., Hammes, U.: Spectrum of pore types and networks in mudrocks and a descriptive classification for matrix-related mudrock pores. AAPG Bull. 6, 1071–1098 (2012)
Mehmani, A., Token-Lawal, A., Prodanovic, M.: The effect of microporosity on transport properties in tight reservoirs. Paper SPE 144384 presented at the North American Unconventional Gas Conference and Exhibition, Woodlands, 14–16 June (2011). doi:10.2118/144384-MS
Polczer, S.: Shale to supply half of North America’s gas. Calgary Herald April 9 (2009).
Roychaudhuri, B., Tsotsis, T., Jessen, K.: An Experimental and Numerical Investigation of Spontaneous Imbibition in Gas Shales. Paper SPE147652 presented at the SPE Annual Technical Conference and Exhibition, Denver (2011).
Sakhaee-Pour, A., Bryant, S.: Gas permeability of Shale. SPE Reserv. Eval. Eng. 15(4), 401–409 (2012). doi:10.2118/146944-PA
Thompson, K.E.: Pore-scale modeling of fluid transport in disordered fiberous materials. AlChe J. 48(7), 1369–1389 (2004)
Valvatne, P., Blunt, M.J. Predictive pore-scale network modeling. In SPE/DOE Annual Technical Conference and Exibition Proceedings. October (2003)
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Mehmani, A., Prodanović, M. & Javadpour, F. Multiscale, Multiphysics Network Modeling of Shale Matrix Gas Flows. Transp Porous Med 99, 377–390 (2013). https://doi.org/10.1007/s11242-013-0191-5
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11242-013-0191-5