NEW TECHNIQUE TO DETERMINE THE EUQUIVALENT VISCOSITY OF DRILLING FLUIDS UNDER HIGH TEMPERATURES AND PRESSURES

Abstract

Using a modified Fann consistometer the equivalent viscosisties of laboratory prepared-, and field muds of different densities have been determined at temperatures up to 500 F and pressures up to 20,000 psi. The study shows that both temperature and pressure affect the equivalent viscosity of invert emulsion muds. The effect of pressure is very pronounced at low temperatures. On the other hand, temperature is the dominating variable in case of water base muds. However, the effect of pressure on the equivalent viscosity of water base muds seems to depend on composition and temperature of the system.