Pore-scale velocity measurements can be achieved by using micro particle shadow velocimetry (µ-PSV). Characteristic properties of a flow are, however, best investigated and described by the pressure distribution in the field. At the pore scale, applying direct pressure measurement techniques comes with significant challenges. By detailed measurement of velocity and applying theoretical relations that suit the flow field under study, the pressure field can be determined. This study demonstrates the application of image-based approaches to investigate the multi-phase flow of a single droplet. Experiments based on µ-PSV are used to determine the velocity field in the flow within the droplet as it passes through a single-pore geometry in the presence of a stationary continuous phase. The results are used to determine the pressure field calculated from a simplified Navier–Stokes expression of the flow, discretised using an Eulerian approach. For the dispersed phase, the theory of the Jamin effect allows the capillary pressure to be related to the observed change in radii of the leading and trailing edges of the droplet. To highlight this approach, two sizes of the glycerol droplets passing through a pore geometry in the presence of a stationary canola oil are investigated. The results show that the velocity and pressure distributions are dictated by the deformation properties of the droplet. The same trends are seen in the distribution of pressure and velocity gradients as a function of location along the channel. The larger of the two droplets showed increased levels of velocity and pressure gradients as it flows through the pore geometry. In general, this work demonstrates the use of the deformation behavior of a dispersed phase to determine the velocity and pressure distributions in a multi-phase flow field.

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Fouling issues are highly undesirable in oil industries, and stable water–oil emulsion is one of the major causes of fouling on pipelines, upgrading equipment, and other surfaces in oil production. Studying the interfacial interactions between emulsion drops and various metal substrates is of significant importance in the fundamental understanding of fouling mechanisms. In this work, surface force measurements using a drop probe atomic force microscope technique and fouling tests were applied to investigate the fouling and antifouling mechanisms of electron-beam-deposited iron substrates with and without electroless nickel–phosphorus (EN) coatings. The effects of oil or aqueous solution conditions have been systematically investigated, including the asphaltene concentration, salinity, pH, and presence of divalent ions. A theoretical model based on the Reynolds lubrication equation and augmented Young–Laplace equation has been applied to analyze the measured force profiles. Our results indicate that the attractive van der Waals force plays an important role in the fouling phenomena, particularly under high-salinity conditions, while the repulsive electric double-layer interaction contributes to the antifouling behavior. Surface force measurements and fouling tests of Fe and EN substrates in toluene-in-water emulsions clearly demonstrate the excellent performance of the EN coating. Our work provides useful insights in the fundamental understanding of fouling/antifouling mechanisms of oil-in-water emulsions on different substrates, with implications to the development of efficient antifouling coatings and strategies in oil production processes.

Summary Studies that investigate and attempt to model the process of steam-assisted gravity drainage (SAGD) for heavy-oil extraction often adopt the single-phase-flow assumption or relative permeability of the moving phases as a continuous phase in their analyses. Looking at the emulsification process and the likelihood of its prevalence in SAGD, however, indicates that it forms an important part of the entire physics of the process. To explore the validity of this assumption, a review of prior publications that are related to the SAGD process and the modeling approaches used, as well as works that studied the emulsification process at reservoir conditions, is presented. Reservoir conditions are assessed to identify whether the effect of the emulsion is strong enough to encourage using a multiphase instead of a single-phase assumption for the modeling of the process. The effect of operating conditions on the stability of emulsions in the formation is discussed. The review also covers the nature and extent of effects from emulsions on the flow mechanics through pore spaces and other flow passages that result from the well completion and downhole tubing, such as sand/flow-control devices. The primary outcome of this review strengthens the idea that a multiphase-flow scenario needs to be considered when studying all flow-related phenomena in enhanced-oil-recovery processes and, hence, in SAGD. The presence of emulsions significantly affects the bulk properties of the porous media, such as relative permeability, and properties that are related to the flow, such as viscosity, density, and ultimately pressure drop. It is asserted that the flow of emulsions strongly contributed to the transport of fines that might cause plugging of either the pore space or the screen on the sand-control device. The qualitative description of these influences and their extents found from the review of this large area of research is expected to guide activities during the conception stages of research questions and other investigations.

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