�?�?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 Whilst chosen, stopping lost circulation fully will not be normally doable or essential. Controlled losses allow drilling to carry on although maintaining the wellbore total, protecting against an inflow of fuel or fluid in