Rheological Measurements of Non-Newtonian Fluids

Abstract

Published in Petroleum Transactions, AIME, Volume 210, 1957, pages 196–201. Abstract The design and performance of many operations common to the petroleum industry depend upon the unique properties of a class of materials known as non-Newtonian fluids. The art of measuring and describing these properties, called rheology, has fallen far behind the field application of these fluids in this industry. Empirical methods are still employed although theoretically sound methods of analysis are now available. This paper illustrates a completely general method of analysis of the rheological properties of non-Newtonian fluids which is independent of the type of viscometer employed and also the rheological type of fluid encountered except those of a thixotropic or rheopectic nature. Values of the rheological properties of a fluid obtained using this method of analysis are based upon an absolute scale of measurement, eliminating the necessity of employing arbitrary concepts of the flow properties of non-Newtonian fluids. The fundamental nature of this method of analysis is further demonstrated by evaluating the precision with which measurements have been made of these rheological properties by employing a dimensionless criteria - the Fanning friction factor-Reynolds number correlation. Introduction Non-Newtonian fluids are not new in the petroleum industry. Particular properties of non-Newtonian materials have been recognized and used to advantage in drilling fluids and have found excellent application in the hydraulic fracturing process. While usage of these fluids is not new in this industry, the art of measuring and describing their rheological properties is still in its infancy. This is reflected in the accepted method of evaluating drilling fluids, API RP 29, (1950), which recommends a one point "viscosity" measurement. These shortcomings are recognized by various groups in the industry and more adequate methods have been proposed.