�?�?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 If the amount of fluid while in the wellbore drops on account of lost circulation (or almost every other explanation), hydrostatic stress is decreased, that may permit a fuel or fluid which can be beneath a higher stress when compar