3. Say the well diameter is 12 inches, and the mud is 10 ppg. If we mix new mud at 10.5 ppg and pump in 100 strokes, a. Where is the interface between the old and new mud? (annulus? Pipe? Exactly what depth..) b. What is the pressure at the bottom of the well now? 1 c. What was it before we pumped in the new mud?

Fig: 1