FLOW OF MUD DURING DRILLING OPERATIONS.

The flow tests of drilling fluids in actual pipes provide definitive data to show that some drilling fluids, particularly low solids non dispersed muds, require less pressure (i. e. , less horsepower) to be pumped to the bit in a drilling operation than other drilling fluids. More importantly, this data also provided friction factor information which can be used to more accurately calculate the pressure requirements to pump a wide range of drilling fluids through the typical flow channels encountered in oil well drilling operations. Calculated pressure losses inside drill pipe have agreed very well with observed field data after initial minor adjustments to the empirical friction factor equation. The formulae utilizing only the routinely measured properties, have proven reasonable for both pressure loss and determination of laminar-turbulent transition in field operations.