�?�?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 Considering that multiple form of drilling fluid loss can current sometimes, it's important to find out the loss types and assess proportion of each loss kind so as to find out the most important and secondary loss styles.