�?�?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 The decrease in annular return circulation will trigger the circulation pace of drilling fluid within the annulus to lower, as well as friction concerning it as well as the annulus will decrease, Therefore the BHP and stand