1. Mud weight High enough to prevent influx from reservoir fluids High enough to ensure wellbore stability Too high mud weight can cause fracturing of the formation Too high mud weight (too high over balance) will slow down the penetration rate

2. Effective mud weight Mud weight of a given fluid will vary with pressure and temperature

3. ESD, equivalente static density

4. ECD, equivalente circulating density Addition to mud weight from friction pressure loss and drill cuttings

5. Measuring mud weight

6. Weighting additives The weighting additives are added to the mud to give it the required mud weight. Barite, Density of 4200 kg/m 3 Hematite, Density of 5100 kg/ m 3 Calcium carbonate, Density of 2700 kg/m 3 In addition can the drilling mud be made up from brine of required density if low solids or solid free mud is required.