�?�?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 decrease in annular return movement will bring about the circulation pace of drilling fluid while in the annulus to decrease, and the friction amongst it and also the annulus will reduce, Hence the BHP and standpipe strain will