Page 569 - Petrophysics

536 PETROPHYSICS: RESERVOIR ROCK PROPERTIES

where Xm is the diameter of the cylinder. For layered or slab
formations

(8.71 c)

where hf is the fracture height, usually taken as the formation thickness
of the fractured zone stacked in between the other layers. Knowing the
inter-porosity parameter h from well test analysis, the fracture height hf
can be calculated from:

hf = rw/T (8.72)

For the sugar-cube model, the side length of each matrix block is obtained
from:

(8.73)

X, = Side Length of the
X, = Radius of the Cubical Matrix Block
Sphere Matrix Block
x,
I

X, = Radius of the
Cylindrical Matrix Block h, = Height of the
Fractured Matrix Slab

Figure 8.26. (a) Spherical, e) cubical, (c) cylindrical, and (d) layered or stacked
matrix blocks with natural fractures.