2 KudoZ points awarded for this answer. Comment: "Merci de votre aide, mais j'ai finalement par traduire par: boue de forage. Après avoir reçu la déf. suivante: Any relatively small quantity (less than 200 bbl) of a special blend of drilling fluid to accomplish a specific task that the regular drilling fluid cannot perform. Examples include high-viscosity pills to help lift cuttings out of a vertical wellbore, freshwater pills to dissolve encroaching salt formations, pipe-freeing pills to destroy filter cake and relieve differential sticking forces and lost circulation material pills to plug a thief zone. "