Additives for oil-based drilling fluids

摘要

An additive for a wellbore treatment fluid comprising a sulfonated asphalt compound comprising particles having a D90 particle size of less than about 215 µm. A wellbore treatment fluid comprising (i) an oleaginous component and (ii) a sulfonated asphalt wherein the sulfonated asphalt comprises particles having a D90 of less than about 215 µm.