Study of the Scale Effect on Permeability in the Interlayer Shear Weakness Zone Using Sequential Indicator Simulation and Sequential Gaussian Simulation

Abstract

Abstract:The interlayer shear weakness zone (ISWZ) is a deformation zone in stratified rock masses, with different width and spacing, due to tectonic stresses. It represents the main flow path in rocks due to higher permeability compared with massive rocks. The permeability values of an ISWZ can vary significantly depending on the scale. This study focuses on the correlations between the permeability properties of ISWZs and their geometry properties. A range of realistic 3-D numerical models of ISWZs is developed using geostatistical modeling, with fine-scale geometry and permeability information taken into consideration. These ISWZs represent a set of mud content and width distributions that are typical for ISWZs. Horizontal and vertical permeability values for all ISWZs are found to change in small-scale samples, whereas these fluctuations decrease with increasing sample size. For different types of ISWZs, the results show that ISWZs with variable width will show a significantly larger scale effect on the permeability than that of ISWZs with constant width. Furthermore, ISWZs with a higher mud content display greater variation in horizontal permeability, while the opposite is true for vertical permeability. Based on the coefficient of permeability variation, a criterion is proposed to identify the calculated permeability of a sample is locally homogeneous. The size for this sample relies on the properties estimated (horizontal and vertical permeability) and geometry features. These findings could provide a basis for the selection of permeability values of an ISWZ in hydraulic engineering. Additionally, the procedures used in this article can be applied to any type of ISWZs.

Estimation of the influence of fracture parameters uncertainty on the dynamics of technological development indicators of the Tournaisian-Famennian oil reservoir in Sukharev oil field

“…According to the statistical data on comparable fields, for the T-Fm reservoirs vertical rock pressure at average rock density of 2,450 kg/m 3 is 48.2 MPa. At average mabs = 11 %, ν = 0.134, and Klat = = 0.155 values lateral rock pressure is 7.45 MPa, which is consistent with the results presented in [28].…”

Median Polish Kriging and Sequential Gaussian Simulation for the Spatial Analysis of Source Rock Data

“…The determined residuals can be analyzed with the kriging method by means of the variogram to study the small-scale spatial structure variation of the study variable and to be combined with the estimated median polish trend [11,12]. MEP is widely used in geostatistical applications to overcome bias as well as the influence of extreme values [13,14], while SGS is used in geostatistical simulation applications in various disciplines [15][16][17]. However, the two methods have never been combined for a specific application, especially in the discipline of hydrocarbons.…”

An Analytical Solution for Non-Darcian Flow on a Constant Head Packer Test in the Interlayer Staggered Zone

“…They are mainly filled by low-permeability fillings (mud and debris) and the high-permeability fillings (gravel and fractured surrounding rock), and the internal structure is loose, with fractured rocks and high content clay in it [17]. As a result, the interlayer staggered zone has a great influence on the stability of engineering works, such as dam breaks, water inrush in underground excavations, seepage deformation, and leakage in dam foundations [18]. The complex structure of the interlayer staggered zone makes the non-Darcian flow more likely to occur.…”