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The high viscosity of heavy oil is a vital parameter that hinders the heavy oil recovery efficiency. Viscosifying aqueous viscosity and reducing oil phase viscosity are the guiding principles under...

Asphaltene stability can be perturbed during the oil production and transportation, leading to asphaltene precipitation and deposition. Chemical inhibitors are usually added to the oil phase to pos...

Spilled oil is highly susceptible to sunlight-induced transformations, both as films on the surface of water and material dissolved or dispersed in the water column. We utilized ultrahigh-resolutio...

Owing to the depletion of light sweet crude, high-temperature corrosion by sulfidation and naphthenic acids in the oil phase has become one of major challenges for crude oil refineries. The corrosi...

Asphaltenes tend to aggregate in different structures depending on the aromatic content of the oil phase. The different aggregates adsorb at the interface as some kind of lipophilic surfactant, whi...

Asphaltenes are the heaviest component of crude oil, causing the formation of a stable oil–water emulsion. Even though asphaltenes are known to behave as an emulsifying agent for emulsion formation, their arrangement at the oil–water interface is poorly understood. We investigated the effect of asphaltene structure (island type vs archipelago type) and heteroatom type (Oxygen-O, Nitrogen-N, and Sulfur-S) on their structural behavior in the oil–water system. Out of six asphaltenes studied here, only three asphaltenes remain at the oil–water interface while others are soluble in the oil phase. Molecular orientation of asphaltene at the interface, position, and angle of asphaltene with the interface has also been determined. We observed that the N-based island type asphaltene is parallel, while the O-based island type asphaltene and N-based archipelago type are perpendicular to the interface. These asphaltene molecules are anchored at the interface by the heteroatom. The S-based asphaltenes (both island and ...

Remaining oil saturation established by waterflooding from maximum initial oil saturation was measured in Indiana limestone under four mixed-wet conditions established using different organic acids. The altered wettability is characterized by the advancing contact angle of the aqueous phase on a calcite substrate submerged in the oil phase, which ranged from θo = 50° to 150°. Remaining oil saturation decayed as a power of time for up to 55 pore volumes of water injected and then reached a constant value. The duration of oil production increased linearly with θo. In contrast, remaining oil saturation decreased and then increased with increasing θo within the range of experimental conditions, with optimal wettability for recovery shifting from θo = 110° to 135° as waterflood progressed.

Mixing conditions were explored as a possible avenue for improvement of demulsifier performance in the solvent-diluted bitumen dewatering process. The effects of demulsifier bulk concentration, demulsifier injection concentration, and mixing energy on water and solids removal from the oil phase were tested. All of the experiments were carried out in a confined impeller stirred tank, which provides well-characterized mixing conditions and relatively uniform flow and turbulence. Results showed that lowering the injection concentration and increasing the mixing energy both improve demulsifier performance, allowing a 50% drop in the bulk concentration of demulsifier. This result agrees well with an earlier study by Laplante et al.1 in which a different demulsifier was investigated. In that study, it was shown that the product of mixing time and energy dissipation rate at the feed point (the mixing energy = J) provides an alternate mixing variable.

Asphaltenes are the heaviest and most polar class of compounds in crude oil, which may precipitate out of solution due to changes in the pressure, composition, or temperature. During production, aggregation between asphaltene solids may lead to viscosification of the oil phase and/or deposition of the solids on the flowline wall. This study presents the first measurement of asphaltene interparticle cohesive forces using a micromechanical force (MMF) apparatus, which is similar to that used previously to investigate gas hydrate interparticle cohesion. Asphaltene solids were precipitated from two crude oils, and cohesive force measurements were performed for particle pairs with diameters ranging from 100 to 200 μm. In air, the measured cohesive forces between the asphaltene particles were approximately one-half of those measured between hydrate particles in cyclopentane-saturated nitrogen vapor. Asphaltene cohesive force was measured in liquid cyclopentane, to provide a comparison against cyclopentane hydra...

The dynamic interfacial tensions (IFTs) of two zwitterionic surfactants with different hydrophobic groups, alkyl sulfobetaine (ASB) and benzyl substituted alkyl sulfobetaine (BSB), against hydrocarbons, acidic model oils containing fatty acids, and three crude oils have been investigated by a spinning drop interfacial tensiometer. The influences of concentration and alkyl chain length of fatty acids on the IFTs of two betaine solutions were expounded. The effect of the alkyl chain carbon number (ACN) of the oil phase on the IFTs has also been researched. The experimental results show that the whole hydrophilic part of the betaine molecule (anionic-cationic part and the hydroxyl) is almost flat at the interface, which results in the larger occupied space of the hydrophilic part at the interface. Therefore, the branched and benzyl-substituted betaine, BSB, has a larger sized hydrophobic part and can form a more compact adsorption film than linear ASB molecules. The IFT values decrease obviously when fatty a...

The structural properties of gelled model waxy oils with different wax concentrations (5–20 wt %) were investigated through a differential scanning calorimetry (DSC) test, rheological measurement, and scaling model for colloidal gels. The wax precipitation curves obtained from the DSC test show that the concentration of precipitated wax crystals φW increases gradually with the decrease of the temperature, and most of the waxes dissolved in the oil phase precipitate at −20 °C. The gelation point increases gradually with an increasing wax concentration from 22 °C at 5 wt % to 26 °C at 10 wt %, then to 32 °C at 15 wt %, and 34 °C at 20 wt %. The structure of gelled waxy oils, similar to the structure of colloidal gels, transits from a strong-link regime to a weak-link regime with the increase of φW, and the value of φW at the transition point is around 1.8 wt % for all of the tested model waxy oils. In the strong-link region, G′E increases while γE decreases with an increasing φW. In the weak-link region, bo...

Breakthrough of alkaline water from one producing zone mixing with formation water and oil from a different zone could potentially give severe calcium naphthenate scaling. In this scenario pre-equilibrated formation water and oil mix with alkaline water that has previously not been in contact with CO2. During mixing alkaline water will increase the pH, while CO2 will partition into the water to lower the pH. It was not known a priori whether CO2 would partition fast enough to inhibit naphthenate formation or if precipitation would occur before CO2 equilibrium had been established. Naphthenate scale risk was therefore examined by mixing formation and alkaline water at down-hole temperature (80 °C) with toluene as the model hydrocarbon. It is shown that CO2 partitioning from the oil phase mitigates naphthenate scale both at high and low shear conditions. Calculation of naphthenate scale potential in such a mixing situation should therefore include CO2 equilibrium between the hydrocarbon and aqueous phase.

There are extensive bitumen deposits in Canada that, with the development of sustainable exploitation technologies, can satisfy the energy requirements of the nation for more than a century. The currently available surface mining and in situ recovery techniques are applicable to only ∼15% of the known in-place resources. There is an obvious need for improved technology to make more of the in-place resources exploitable. This paper is aimed at studying the macroscale performance of the steam-assisted gravity drainage (SAGD) and the solvent-aided SAGD (SA-SAGD) processes. A two-dimensional (2-D) physical model of porous media was designed and fabricated for the purpose of implementing these two processes. The physical model was packed with different sizes of glass beads to create porous media with different permeability values. Athabasca bitumen was used as the oil phase. All the SAGD and SA-SAGD experiments were performed in an isothermal jacket as the controlled-temperature environment to reduce the amoun...

In this study, the microscopic displacement mechanisms of alkaline flooding for enhanced heavy-oil recovery are investigated using a micromodel. It has been observed that alkaline flooding exhibits a better sweep efficiency than waterflooding, and the serious viscous fingering is significantly reduced. The main microscopic mechanisms of alkaline flooding for enhanced heavy-oil recovery are that the alkaline solution penetrates in crude oil and water drops are, subsequently, formed inside the oil phase, which can improve the mobility ratio and, thus, lead to the improvement of sweep efficiency. The higher the alkaline concentration, the more easily the alkaline solution penetrates in the oil phase. Therefore, a greater improvement in sweep efficiency can be obtained using a higher concentration of alkali. The primary mechanism of the formation of the water drop inside the oil phase during alkaline flooding is related to the interfacial interaction between alkali and heavy oil, which not only results in the...

Experimental studies have been conducted to explore the mechanisms responsible for the dynamic interfacial tension (IFT) behavior in surfactant/model oil systems. Two multi-n-alkylbenzene sulfonates with high purity were selected as model components, and the dynamic IFTs of the two surfactant solutions against a homologous series of alkanes were measured. The effect of n-octadecanol in oil phase on dynamic IFT behavior has been investigated. The experimental results show that there exist two types of the dynamic IFT curves: for one type of curve, the IFT value drops quickly to the stable value, and for the other type, the IFT value passes through a minimum quickly and soon increases to the stable value. The hydrophilic−lipophilic ability of the surfactant plays the most important role in dynamic IFT behavior. The addition of n-octadecanol will result in the appearance of the IFT minimum at hydrocarbons with a larger alkane carbon number, which can strongly support our explanation.

International audience; In the presence of a large excess of asphaltenes in oil phase, an interfacial tension anomaly (a small bump of the order of 1 mN/m), is found to correspond to the optimum formulation where the fastest water-in-oil emulsion breaking is observed. This correspondence, also observed for other systems, indicates that strong interaction should occur between asphaltenes and demulsifiers. Therefore, the optimum formulation would correspond to a situation where there is enough demulsifier to remove the asphaltenic interfacial gel by orogenic displacement, but not too much to cause adsorption of large asphaltenic/demulsifier complexes which would slow down emulsion drainage.