The Rheology of Crude Oil Dispersions
Authors: Camy J.P. , Marsden S.S. , Hung-B. J.E. , Arihara N. , Casse F.J. , Alvarado-Q. D.A. , Mandel L. , Mobarak S. , Gonzalez-G. H.O. , Mao M.L. , Samaniego-V. F. , Romero-G. E. , Rivera-R. J. , Marius C.G. 
Published: December 2007

Camy, J.P., Marsden, S.S., Members SPE-AIME, Hung-B., J.E., Arihara, N., Member SPE-AIME, Casse, F.J., Member SPE-AIME, Alvarado-Q., D.A., Member SPE-AIME, Mandel, L., Mobarak, S., Member SPE-AIME, Gonzalez-G., H.O., Mao, M.L., Samaniego-V., F., Romero-G., E., Rivera-R., J., Member SPE-AIME, Marius, C.G., Stanford U.

American Institute of Mining, Metallurgical, and Petroleum Engineers, Inc.

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Introduction

The word 'emulsion' is well known to every petroleum engineer. It simply describes an petroleum engineer. It simply describes an undesirable mixture of oil and water which must be separated before the pipeline will accept his oil. Given the choice, he would rather not have an emulsion because it just means another oilfield problem he has to solve. In the minds of most petroleum engineers, all emulsions are bad. One of the goals of this work has been to demonstrate that this is not necessarily true.

The petroleum engineer deals mainly with one of the two main types of emulsions. This is the so-called water-in-oil type (W/O), i.e., one which consists of water droplets dispersed in a continuum of oil. The second kind is the oil-in-water (O/W), i.e., one which consists of oil droplets dispersed in water. This second type is well-known elsewhere in science and engineering and is beginning to be better known in the petroleum production industry. As we shall see, petroleum production industry. As we shall see, the physical properties of the two types can be quite different.

Through a better understanding of the conditions under which each type will exist, we can perhaps use these distinctive physical properties to advantage. This has been the second properties to advantage. This has been the second goal of this research.

Of the various physical properties of emulsions, those associated with flow are perhaps the most important to the petroleum engineer, and therefore we chose to study them. If we had been physical scientists we might have chosen the equally interesting and distinctive properties of electrical conductivity or properties of electrical conductivity or dielectric constant. The flow or rheological properties of emulsions have been studied by properties of emulsions have been studied by many people in the past, but most have used emulsions containing small amounts of the dispersed phase and have considered them as Newtonian fluids. We chose to study emulsions containing higher concentrations of the dispersed phase which are more difficult to work with. More recent research in our laboratory and elsewhere has shown that these often behave like non-Newtonian fluids and hence simply describing their rheological properties in terms of a viscosity is not adequate. properties in terms of a viscosity is not adequate. Most research with emulsions has involved the use of water, relatively pure hydrocarbons and some kind of chemical emulsifying agent which aids in the preparation of the emulsion and contributes to its stability. Although we have known for a long time that crude oils are more than mixtures of hydrocarbons, we are only now beginning to realize that the chemistry of crude oil, particularly the chemistry of the non-hydrocarbon constituents, is important in petroleum engineering. As we shall see, these same aspects of chemistry are important for emulsions made with crude oil.