�?�?t ρ l k + �?�?x i ρ l k v l = �?�?x j μ + μ t σ k �?k �?x j + G k �?ρ l ε �?Y M The purely natural fractures encountered in the actual drilling course of action are not parallel fractures using a uniform width alongside the length with the fracture. Over the loss course of action, in the event the fluid stress