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Bottle testing for emulsion breakers (EBs) in steam-assisted gravity drainage (SAGD) operations is a standard practice; however, it has been observed that, in some cases, EBs recommended via bottle tests can fail during field trials as a result of conditions being disparate, such as higher temperatures and pressures in the field that cannot be safely or easily replicated in the lab. To make better EB recommendations, an optimized methodology based on interfacial rheology measurements was developed. Compressibility tests performed at different temperatures (80–120 °C) were used to compare effect of EBs on parameters such as initial compressibility, initial interfacial tension, phase transition ratio, and drop crumpling or detachment ratio (ratio of the compressed surface area to the original surface area at which the interface starts to collapse or at which the drop detaches). Furthermore, the addition of the EB to the oil phase versus aqueous phase was investigated. The effects of EBs at the oil/brine int...

Steam-assisted gravity drainage (SAGD) is one of the unconventional methods used in Canada to extract heavy oil; however, a stable water-in-oil-in-water (W/O/W) emulsion is generated during production. The emulsion is then pumped into a high-temperature separator, after adding a diluent, a reverse emulsion breaker (REB), and an emulsion breaker (EB) to separate the oil and water and comply with the sales oil specifications. This work is focused on understanding the demulsification processes under high-temperature (80–120 °C) and high-pressure (700–900 kPa) conditions. Compressibility, crumpling film or drop detachment ratios, and interfacial tension (IFT) were used to evaluate the demulsifiers. REBs were found to decrease IFT and cause the interfacial film to be reversible. These effects showed a dependency with the temperature, and their magnitude varied with the chemistry of the REB. Effective REBs formed complexes with natural anionic surfactants present in the oil phase, weakening the irreversible fil...

In steam-assisted gravity drainage (SAGD) operations, the produced fluids are complex water-in-oil-in-water (W/O/W) emulsions. A diluent is often added to reduce the density and viscosity of the heavy crude oil. However, the quality and composition of the diluents may in some cases increase emulsion stability and cause the dehydration of the oil to be more difficult because there are more surface-active agents added to the oil coming from the diluent streams. Thus, this work was aimed at studying the effect of three different diluents on interfacial film formation of a Canadian heavy oil. Interfacial elasticity and compressibility were evaluated, and the results were then correlated with emulsion stability. The wettability of the systems was also studied. The systems studied behaved as if a bidimensional gel near its gelation point had organized at the interface, in which adsorbed amphiphilic materials, such as asphaltenes and resins, self-aggregated at the interface, forming a network that acts as a stab...

Dielectric relaxations of polycarbonate (PC) and poly(e-caprolactone) (PCL) blends that were thought to be completely homogeneous in the amorphous phase from many previous calorimetric studies are performed by using the thermally stimulated depolarization currents technique. Samples kept for 18 months at room temperature were compression-molded and then either quenched or slowly cooled. Quenched samples evidenced a phase separation for the 20/80 PC/PCL composition and the existence of continuous concentration fluctuations for other blend compositions. The slowly cooled samples from the melt exhibited an increase of the crystallinity degree for both blend components, together with a segregation of a predominantly rich PCL phase and the appearance of high-temperature relaxations attributed to interfacial polarization. These findings are confirmed by new calorimetric results on the same blends and by transmission electron microscopy. The spherulitic growth rate also points to the coexistence of two phases wh...

The confinement of crystallizable blocks within AB or ABC microphase-separated block copolymers in the nanoscopic scale can be tailored by adequate choice of composition, molecular weight, and chemical structure. In this work we have examined the crystallization behavior of a series of AB and ABC block copolymers incorporating one or two of the following crystallizable blocks: polyethylene, poly(e-caprolactone), and poly(ethylene oxide). The density of confined microdomain structures (MD) within block copolymers of specific compositions, in cases where the MD are dispersed as spheres, cylinders, or any other isolated morphology, is much higher than the number of heterogeneities available in each crystallizable block. Therefore, fractionated crystallization takes place with one or several crystallization steps at decreasing temperatures. In specific cases, the clear observation of exclusive crystallization from homogeneous nuclei was obtained. The results show that, regardless of the specific morphologica...

The preparation of polystyrene-b-poly(ethylene oxide)-b-poly(-caprolactone) triblock co- polymers using three different strategies is described. Experimentally, a method we have called "thermal" is the simplest one of the three employed. However, it presents serious limitations for the preparation of high molecular weight triblock copolymers with low polydispersity. The titration method is a more elegant alternative to prepare the PS-b-PEO-b-PCL triblock copolymers. Nevertheless, the stoichiometric titration of the precursor terminal hydroxyl groups requires much expertise, and it becomes more difficult as the concentration of such terminal groups decreases when the precursor molecular weight increases. Finally, the sequential method may be regarded as the most convenient one. However, the experimental steps involved a solvent exchange during polymerization that must be performed under conditions of strict purity and high vacuum. Several triblock and pentablock copolymers of varying compositions and molecular weights were successfully prepared. The fact that these copolymers contain two crystallizable blocks, i.e., PEO and PCL, makes them very interesting from a structural point of view. The copolymers were found to be phase segregated according to evidence provided by DSC and WAXS. The crystallization and melting behavior of both PEO and PCL blocks is greatly affected by composition. Fractionated crystallization phenomena were detected when either one or both blocks constituted the minor components within the block copolymers.

The microphase morphology of a polystyrene-block-polybutadiene-block-poly(e-caprolactone) SBC triblock copolymer is studied through transmission electron microscopy. Even though crystallization of the PCL block takes place well below the PS glass transition, lamellar microphases and the formation of well-defined spherulites are observed. The typical long-range order normally obtained for amorphous triblock copolymers is not obtained in the SBC triblock copolymer. The morphology of a polystyrene-block-poly(e-caprolactone) diblock copolymer was also observed and compared with the triblock copolymer. To investigate whether the crystallization temperature (Tc) is a parameter influencing the final morphology, samples of the triblock copolymer were crystallized at 45 and 42 °C. This reduction in Tc results in a morphological transition from a simple lamellar morphology (PS, PB, and PCL form layers), which we call lamellar−lamellar (ll), to a lamellar−cylindrical (lc)-morphology with PS and PCL layers and PB cyl...

The relationship between the microphase morphology and stress−strain behavior of a polystyrene-block-polybutadiene-block-poly(e-caprolactone) SBC triblock copolymer has been investigated with polystyrene as the major component. The semicrystalline PCL block does not change significantly the basic morphology, but it affects the form of the microdomains, so that S57B27C16 shows a “polygonal” core shell morphology in a PS matrix. This morphology seems to be the consequence of crystallization in the inner PCL cylinders inducing deformation of the microdomains, which may create interfacial stresses. These stresses can generate small microcrazes upon external loading which may be responsible for the high elongations at break in this material. Moreover, the long-range order of the microdomains, which can be affected through the preparation conditions, determines the stress−strain behavior. Copolymers with 57 and 51 wt % PS and a corresponding “PS matrix” exhibit elongations at break up to ∼800%.

4-Urazoylbenzoic acid groups are attached to the chain ends of polyisobutylene. The cooperative assembling process of these polar groups is studied by DSC and dielectric and dynamic mechanical spectroscopy. The melting of the ordered clusters occurs in the temperature range 380-390 K. Distortions within the U4A clusters (Σ process) are monitored below the melting temperature T m with dielectric spectroscopy. On a larger length scale, these distortions also lead to stress relaxation which can be probed by dynamic mechanical measurements. Near T m , the relaxation ofU4A multiplets (α* relaxation) is detected with dielectric spectroscopy. In this temperature range, dynamic mechanical measurements show a transition from elastic behavior to viscous flow. The results are rationalized with molecular modeling calculations.