High-Density Invert-Emulsion System with Very Low Solids Content to Drill ERD and HPHT Wells

Abstract

Abstract The paper describes the laboratory development of a new Low Solids Oil Based Mud System (OBMS) with a very high specific gravity (2.04 SG; 17 ppg) for high-temperature and high-pressure applications. The system can also be applicable as solid free oil based mud with very low viscosity at densities up to 1.52 SG, especially suggested for Extended Reach Drilling Wells. The main goals of the new system are: Optimization of fluid rheology by reduction of the solids contents in the mud. Temperature and system stability at 170 °C. The objectives have been pursued in the following ways: – by using a very heavy brine as the internal phase; – by decreasing the oil / brine ratio; – by using a weighting agent with higher density than barite. In this way, the amount of weighting solids which needs to be added can be drastically reduced to even below 22% v/v for a 2.04 SG mud, compared to 35% v/v as in traditional oil based muds. Also the PV values have been reduced from typically round 60 cP to even below 25 cP. The addition of new components to the system has lead to the need of a new emulsifier package, which has been optimized with the development of a primary emulsifier and a wetting agent based on innovative chemistries.