The marsh funnel and drilling fluid viscosity: A new equation for field use

The flow behavior of a Marsh funnel was numerically simulated for power law fluids and was found to give good agreement with experimental measurements . As a result, the simulation provides a general picture of the meaning of the Marsh funnel time and a correlation enabling this to be converted into a value for effective viscosity of non-Newtonian fluids. For field use, the following equation relates the effective viscosity mu(e) (cp) to the Marsh funnel (quart) time t (seconds) and the density rho(g/cm(-3)) mu(e) = rho( t-25).