Va Munoz

Characterization of Bitumen Properties Using Microscopy and Near Infrared Spectroscopy: Processability of Oxidized or Degraded Ores

Oxidized or degraded oil sands can exhibit poor processability, which is often not correlated with the fines or clay contents in the ore. Chemical markers (such as low pH and high soluble iron and calcium) for oil sands oxidation are sometimes not present even though significant changes in bitumen properties may have occurred. In these cases, changes in bitumen chemistry have been successfully quantified using microscopic techniques developed at CANMET. More recently, an on-line tool using near infrared (NIR) spectroscopy, which correlates with the CANMET microscopic method, has been developed with Suncor Energy Inc. An on-line technique based on NIR that can quantify the amount of degraded ore coming to the extraction plant from Suncor Energy Inc.s Steepbank mine will be useful in effectively controlling additions of process aids for treating oxidized or degraded ores. This paper discusses the processability of oxidized or degraded ores along with a microscopic method for identifying oxidized ore and its correlation with the NIR spectroscopic technique.

The morphology of non-equilibrium foam and gelled foam lamellae in porous media

Abstract Low energy, replica-based, and cryogenic scanning electron microscopy, and reflected visible light and fluorescence modes of confocal laser scanning microscopy, were applied to the imaging of mobile, non-equilibrium polymer-thickened and gelled-foams in porous media. As a result information was obtained about the morphology of some non-equilibrium foam lamellae in real porous media. In contrast to equilibrium (or near-equilibrium) foam, the structure of these non-equilibrium, viscous foams flowing through porous rock is quite similar to that observed in etched-glass micromodels. The foam films are lamellar, three-dimensionally arranged in various structures, and exhibit foam lamellae thicknesses ranging from about 1–12 μm. This thickness range is much narrower than is observed for bulk dynamic foams. The present measurements also show that foam lamellae in porous media can extend for considerable distances, greater than the length of individual pores, if oriented parallel to the overall direction of flow. In other cases, foam lamellae can span across the entrances to multiple pores. In the context of improved oil recovery, the latter configuration would cause blocking and diverting of injected fluids whereas the former configuration would cause only reduced permeability of the pores to injected fluids. These results are important to the optimal design of polymer-thickened and delayed-gelling foams for water shut-off applications in the near-wellbore regions of oil and gas producing wells, and for blocking and diverting applications in reservoirs undergoing secondary and tertiary flooding processes.

The Use of Microscopic Bitumen Froth Morphology for the Identification of Problem Oil Sand Ores

Abstract Oil sand, which is found in various deposits around the world, consists mostly of sand, surrounded by up to 18 wt% bitumen. The largest deposits known are situated in northern Alberta, Canada, where reserves of bitumen are estimated to be 1.7 trillion barrels. Bitumen is similar to heavy oil, but with much higher viscosity and density. The two main commercial oil sand operations in Alberta are surface mines and use aqueous flotation of the bitumen to separate it from the rest of the oil sand. Under optimal conditions up to 95% of the bitumen can be recovered, but occasionally ores are mined that create problems in extraction, and recovery can drop to 70% or less. This article discusses the microscopic morphologies of various bitumen and heavy oil streams and their relationship to processing problems. The results of extensive microscopic work have demonstrated that the bitumen in an oil sand ore is the phase most susceptible to oxidation and that the resulting changes manifest themselves in particular microscopic structures. The presence and type of these structures can be related to the processing behavior of oil sand ores. Morphological features found in froths from commercial operations are similar to those found in froths from laboratory-prepared samples. The morphological features found in froths of oxidized ores have been categorized and quantified for a variety of samples and are referred to as degraded bitumen structures. Experiments in which fresh oil sand ores were subjected to low-temperature oxidation showed that bitumen froth morphology changed dramatically compared to that of nonoxidized ores for identical bulk compositions and extraction water chemistries.

Microscopic characterization of oil sands processing emulsions

Microscopic characterization of oil sands emulsions can be important in the prediction of processing characteristics and process yields in the extraction of oil from oil sands. The size distribution of the emulsion can determine how efficiently the oil can be separated from the water and by what means: mechanically or chemically. In addition, it is possible to characterize the nature of the dispersed phase by using fluorescence behaviour under an optical microscope or via x-ray analysis with a scanning electron microscope. In certain cases it is also possible to characterize the interface between the dispersed and the continuous phases. This paper presents results from our laboratory using microscopic techniques and illustrates their utility, not only for determining the morphology of these economically important emulsions, but also to characterize the composition of the interface itself.