Invert Emulsion Mud
Invert Emulsion Mud system has water-in-oil emulsion. It has oil as continuous phase and brine as internal phase. Typical oil/brine ratios range from 95/5 to 50/50 in invert emulsion systems. Invert emulsions are usually tightly emulsified, low fluid loss oil muds. Relaxed Invert Emulsion mud is the one with relaxed fluid loss control, which have proven to improve drilling rates.