ZHANG Zhao-bin¹, LIN Mian^2*, LI Xiao¹
1. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;
2. Institute of Mechanics, Chinese Academy of Sciences, Beijing 100190, China

Abstract: Flow path tortuosity, which is of great significance to productivity forecast, is an important parameter in characterization of the transport process in porous media. However, due to the nonlinearity of flow in tight reservoirs, flow properties in tight reservoirs are remarkably different with those in the regular reservoirs, thus is the tortuosity. We studied the change of tortuosity caused by the nonlinearity of flow using a pore network model. Two dimensionless numbers were introduced: one is the dimensionless tortuosity, Γ, which is defined based on hydraulic tortuosity to quantify the change of tortuosity due to the nonlinearity of flow in tight reservoir; another is the dimensionless pressure gradient, Ρ, which is defined on the basis of the flux-weighted throat radius to quantify the state of pressure gradient. The dependency of Γ with Ρ was systematically studied. The Ρ-Γ curve was found to have a fix shape and was irrelevant with any parameters of the core. The result implied that, the change of tortuosity caused by the nonlinearity of flow in tight reservoir is only a function of dimensionless pressure gradient. The change of tortuosity can be calculated directly by the fitting formula of Ρ-Γ curve presented in this work.

Keywords: tight reservoir tortuosity pore network model Bingham fluid

*Corresponding Author, E-Mail: linmian@imech.ac.cn

Bulletin of Mineralogy, Petrology and Geochemistry Vol. 34, No.1, 2015, page 55-60