IMPROVED PRESSURE-DROP FLOW-RATE EQUATION FOR NON-NEWTONIAN FLUIDS IN LAMINAR-FLOW

Most fluids used in the oil industry show some degree of non-Newtonian behavior. To obtain reasonable pressure drop calculations, therefore, one must take this into account. Examples of non-Newtonian fluids are drilling muds, cements, waxy crude oils, polymer-water solutions and so on. This paper uses a three-parameter rheological model, the Collins-Graves model, to derive a flow rate-pressure drop relation for non-Newtonian fluids. The objective is to provide a relatively accurate but simple tool to estimate pressure drop for tubing of any size. The input data are rheological constants obtained from a viscosimeter.