Page 161 - Applied Petroleum Geomechanics

154 Applied Petroleum Geomechanics

Figure 4.12 The outcrop showing steep bedding planes (right side) and a fault (in the
middle) in Arbuckle mountain, Oklahoma.

Figure 4.13 Two orthogonal sets of joints within siltstones and black shales of the
Utica shale outcrop near Fort Plain, New York.

mountain, Oklahoma. Fig. 4.13 demonstrates rectangular joint networks
within siltstones and black shales of the Utica shale outcrop, a similar
behavior found in the Marcellus shale, where two orthogonal joints (J 1 and
J 2 ) exist. Natural fractures can also be found in cores, and Fig. 4.14 displays
that natural fractures are perpendicular to the bedding planes in the
Wolfcamp cores. Those vertical fractures may be beneficial for hydraulic
fracturing and enhancing oil production.
For complicated fracture networks, a computational model is needed
and named ‘‘discrete fracture network” (DFN). The DFN is a three-
dimensional geometric representation of joints present in a rock mass. It
explicitly represents the geometrical properties of each individual fracture