Abstract

The operation of enhanced oil recovery field pilots is dependent upon theproduction technique used to treat difficult emulsions. This paper describesthe data gathered on three different enhanced oil recovery field pilots. Theresults show that by monitoring Fluid properties the progress of the enhancedail recovery pilots can be observed. The characterization of produced wellheademulsions at regular intervals will be beneficial in assessing the field pilotperformance and may provide valuable information to understand enhanced oilrecovery mechanisms.

Some preliminary results are reported on the demulsification of fire floodemulsions. The importance of the mixing method is highlighted.

Introduction

The enhanced oil recovery methods, currently being applied in the production ofheavy oil, generate emulsions which are difficult to treat. Severe emulsionscause production shutdown and/or a significant increase in the use of treatingchemicals. Oil companies have recently resorted to other methods, such as flashevaporation, to clean up these difficult emulsions. 1Flashevaporation techniques, when applied to cases involving saline water, canproduce unacceptable salt levels in the crude and can pose desalting problemsfor the upgrader and/or refiner. Emulsion characterization is needed to assessall aspects of recovery, treatment and upgrading problems. These "emulsioncharacteristics" will show the effects of the problems generated in thereservoir and can signal potential problems in treatment and upgrading steps.This paper describes the results of a research project on the "characterizationand treatment of emulsions using Field-produced emulsions. The data and resultsgiven here are an update of a previous paper presented at the Heavy Oil Conference at the University of Saskatchewan.2

EXPERIMENTAL
Emulsion Characterization

Several wellhead emulsion samples were collected from the Battrum fire flood(Mobil), the Eyehill fire flood (Murphy) and the Meota steam pilot (Canterra).These emulsion samples were characterized by percentage of free water, BS&:W and microscopic examination of the oil phase, and for viscosity. The Meota and Battrum samples were separated into oil and water using a high speedcentrifuge but the Eyehill emulsions required the addition of a neutraldemulsifier for separation.

The oil components were characterized by acid number, viscosity, gravity, sulfur and asphaltene and the water components of the emulsions werecharacterized by the concentration of sodium, chloride and bicarbonate, sulfate, pH, conductivity and organic acids. Selected samples were analyzed atthe University of Calgary using NIPPY-MS (Non-Isothermal Programmed Pyrolysis Mass Spectrometry).

Wellhead samples were collected on two occasions From Eyehill and Meota toobserve time dependent changes in the properties of produced fluids.

Emulsion Treatment

During the last three years many chemicals have been tested for the demulslF1.cation of f1.reflood emulsions. It was concluded that each problememulsion required a different chemical and that only a trial and errorprocedure can be used for selecting the chemical. An attempt was also made totest mechanical methods for demulsification. A demulsifying device (patentpending) to Improve the rate of demulsification was developed.

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