Randy Mikula

Mechanisms of Crude Oil–Mineral Interactions

Abstract The formation of oil–mineral aggregates (OMA) in water is initiated by a variety of physical and chemical factors that are not readily amenable to differentiation in the field or in the laboratory. This study illustrates a method that may be used to isolate the limiting parameter responsible for the formation and stabilization of OMA based on the microstructure and sedimentation characteristics of the aggregates. A flocculation index based on the sedimentation behavior of a sheared crude oil–mineral–water mixture was used to quantify the degree of interaction of oil and minerals in water. The degree of crude oil–mineral interaction was found to be dependent on the viscosity of the crude oil and the type of mineral present. Hydrophilic quartz and kaolinite interact more strongly with low-viscosity oils than with high-viscosity oils, whereas calcite (an oleophilic mineral) interacts strongly with crude oils irrespective of their viscosities. It was observed that the water chemistry must favor flocculation before the minerals can effectively stabilize oil–mineral flocs. In a fresh water analogue, quartz and kaolin interact more strongly with crude oils than montmorillonite but the reverse is true in seawater. Calcite flocculates crude oils in fresh or seawater more strongly than the hydrophilic minerals tested. In all the minerals tested, the degree of oil–mineral interaction increases and then plateaus as mixing energy is increased. Confocal laser images of the oil–mineral structures reveal two types of OMA. In low-viscosity oils with hydrophilic minerals, negatively buoyant flocs comprising minerals stabilizing oil droplets in a water-continuous phase are predominant. OMA with calcite show mineral-stabilized oil droplets and mineral-rich positively buoyant oil-continuous phase.

Ultrahigh-resolution mass spectrometry of simulated runoff from treated oil sands mature fine tailings.

There is interest in using mature fine tailings (MFT) in reclamation strategies of oil sands mining operations. However, simulated runoff from different dried MFT treatments is known to have elevated levels of salts, toxic ions, and naphthenic acids, and alkaline pH and it is phytotoxic to the emergent macrophyte, common reed (Phragmites australis). Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) of the acidic species in the runoff confirmed that the distribution of oil sands naphthenic acids and associated oil sand acids was dependent on the MFT treatment. Furthermore, FT-ICR MS studies of the acidic species in hydroponic systems revealed that there was no plant-mediated change in the electrospray ionization mass spectra of the runoff. O(o)-containing species were prevalent (>90%), O(o)S(s) were predominant (<10% relative abundance), and O(o)N(n) were least abundant in all runoff water samples. O(o)S(s) species were predominant in all the samples investigated. The heteroatomic classes present in runoff water at greater than 1% relative abundance include: O(2)N(1), O(3)N(1), O(2), O(2)S(1) O(3), O(3)S(1), O(4), O(4)S(1), O(5), O(5)S(1), O(6), O(6)S(1), O(7), O(7)S(1), O(8) and O(8)S(1). Assuming the same response factor for all O(o) species, the O(4) class, presumably dicarboxylic acids, was generally more prevalent than the O(2) class in all samples. The O(2) class is indicative of classical naphthenic acids. However, dicarboxylic acids will form negative ions more readily than the monocarboxylic acids as there are two acidic hydrogens available for formation of these species.

Centrifugation Options for Production of Dry Stackable Tailings in Surface- Mined Oil Sands Tailings Management

Water availability is beginning to impact oil sands development and, as a result, several technologies to increase the percentage of recycled water are being evaluated. One such option being re-evaluated is the use of centrifuges to produce dry tailings that can accommodate overburden and soil replacement. Previous evaluations of centrifuge performance to capture water from the clay and silt tailings (mature fine tailings) components demonstrated some success but, at the time, at unacceptable costs. A better appreciation of the long-term costs of mature fine tailings storage has prompted a re-evaluation of centrifuge technology. The use of additives to improve centrifuge performance has significantly improved the results that can be achieved. Aside from the obvious positive environmental benefit of reclaiming the fluid fine (mature fine) tailings, the increase in the amount of water recycled will reduce the demand for fresh water from the Athabasca River. This paper discusses a laboratory-scale study of the water chemistry and clay/silt feed properties affecting centrifuge performance, as well as the results of a 20 tonne per hour pilot.

Phytotoxicity and naphthenic acid dissipation from oil sands fine tailings treatments planted with the emergent macrophyte Phragmites australis

During reclamation the water associated with the runoff or groundwater flushing from dry stackable tailings technologies may become available to the reclaimed environment within an oil sands lease. Here we evaluate the performance of the emergent macrophyte, common reed (Phragmites australis), grown in chemically amended mature fine tailings (MFT) and simulated runoff/seepage water from different MFT drying treatments. The present study also investigated the phytotoxicity of the concentration of oil sands naphthenic acids (NAs) in different MFT drying chemical treatments, in both planted and unplanted systems. We demonstrate that although growth was reduced, the emergent macrophyte common reed was capable of growing in diluted unamended MFT runoff, as well as in diluted runoff from MFT amended with either 0.25% lime and gypsum or 0.5% gypsum. Common reed can thus assist in the dewatering process of oil sands MFT. However, simulated runoff or seepage waters from chemically amended and dried MFT were phytotoxic, due to combined levels of salts, naphthenic acids and pH. Phytoremediation of runoff water/ground water seepage from dry-land applied MFT will thus require pre-treatment in order to make conditions more favorable for plant growth.

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.