�?�?t ε l ρ l v l + �?�?ε l ρ l v l v l = ε l �?�?τ l + ε l ρ l g �?ε l �?p �?β v l �?v s If the level of fluid within the wellbore drops as a result of lost circulation (or any other cause), hydrostatic stress is reduced, which could let a gasoline or fluid and that is below an increased stress in comparison to