Abstract.

Many crude oils discovered in Western Canada display unusual flow properties at the temperatures encountered during storage and pipeline transportation.

Careful consideration of deviations from Newtonian behavior is essential to the accurate design of most flow systems associated with these liquids.

The characteristic behavior of Newtonian, pseudoplastic and time dependent or thixotropic crude oils is reviewed with reference given to the techniques involved in the measurement and interpretation of the rheological data.

Examples are presented to illustrate the rather wide variations which are possible within each of the three classifications.

Application of rheological data to the design of crude oil pipelines is discussed with the aid of examples. The complications arising from the shear rate dependence of pseudoplastic crude oils and the shear rate and time dependence of thixotropic crude oils are considered under both laminar and turbulent flow conditions.

Résumé.

Bien des huiles minérales découvertes dans l'Ouest Canadien présentent une rhéologie non-newtonienne aux températures de stockage, de pompage et d'écoulement en pipe-lines, rencontrées dans les climats du nord. Un projet de pipe-lines bien conçu tient compte de la connaissance des différents types rhéologiques, de leur estimation et de l'interprétation exacte de leurs caractéristiques.

Les caractéristiques rhéologiques des huiles minérales découvertes en Alberta, au Canada, sont discutées. Les procédés de laboratoire servant à déterminer leur comportement au cours de l'écoulement et leurs caractéristiques rhéologiques sont décrits et des données essentielles présentées et discutées.

Les différentes conceptions de pipe-lines pour huiles minérales ordinaires pseudoplastiques sont passées en revue et les complications survenant du fait de la pré- sence occasionnelle de la thixotropie sont discutées. On compare la capacité théorique des pipe-lines types et leur capacité réelle.

Introduction

The design of pipelines for the transportation of crude oil is based upon a knowledge of the consistency and density of the oil under the anticipated operating pressure and temperature. Many crude oils exhibit normal or Newtonian consistency behavior but some are not so simply described. This is especially the case under the lower operating temperatures found in the northern climates.

Over the past several years the authors have had the opportunity of measuring the consistency behavior of a good number of Western Canadian crude oils and have found anomoloiis behavior of varying degrees in many of them. This non-Newtonian behavior is not unusual in liquid mixtures of complex composition and is well known, although still not completely understood, by those who study rheology.

It has, however, not been fully appreciated by pipe-

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