�?�?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 paper will deal with the next major subjects: Deep well drilling systems are of significant worth while in the drilling sector. In this process, the drilling fluid (drilling mud) is used to take care of strain balance,