A. Babchin

Electroacoustic method for monitoring the coalescence of water-in-oil emulsions

Abstract Ultrasound vibration potential which involves the application of an ultrasonic field and the detection of an electric field, was a well suited technique for electrokinetic measurements of colloidal systems in non-polar and non-transparent media. The technique was used to monitor the rate and extent of coalescence in water-in-crude oil emulsions. The effect of water content, demulsifier type and concentration was studied. The change in ultrasonic vibration signal correlated well with the results from centrifugation and photomicrography which were also used to follow the demulsification process. The results also showed that the use of a combination of a demulsifier and a surfactant was more effective in separation than the individual chemicals.

Gas bubble nucleation kinetics in a live heavy oil

Abstract The current primary production of heavy oil and bitumen is highly dependent on the development of ‘foamy oil’, heavy oils containing dispersions of long-lived bubbles of gas. The nucleation and initial growth of these bubbles are key elements of the behavior of foamy oils. The tremendous levels of supersaturation associated with the expansion of live heavy oils within a porous medium can generate large numbers of small bubbles. Colloidal and interfacial science techniques were used to develop a kinetic model of the nucleation and initial coalescence of gas bubbles from the live oil. Expanding a live, heavy oil within a porous medium in laboratory experiments allowed the pressure deficit driving bubble formation to be quantified. The kinetic model and experimental data were used to calculate critical bubble radii, spacing and saturation. The large number of small bubbles predicted by the kinetic model provides an explanation for the pressure deficit observed in the volume expansion experiments. A significant amount of energy is spent on the creation of new interfaces.

A model of chaotic evolution of an ultrathin liquid film flowing down an inclined plane

Chemical and colloidal transport processes in partially saturated porous and fractured media are dependent on liquid flow along a solid surface, which may be chaotic even for small Reynolds numbers. This paper presents the derivation of a one-dimensional evolution equation describing the slow motion (small Reynolds numbers, R<<1) of a very thin liquid film flowing down an inclined impermeable plane. In this equation, gravitational, capillary, and molecular forces are taken into account. The addition of the molecular force term leads to a highly nonlinear equation governing the spatial and temporal evolution of film thickness. In a weakly nonlinear limit, this evolution equation is rescaled to a canonical form. The latter predicts a chaotic hydrodynamic instability for the film surface. This chaotic behavior is illustrated using the 3D projections of pseudo-phase space attractors for the spatial and temporal variations of the dimensionless film thickness.

Generalized Phase Mobilities In Gravity Drainage Processes

Adequate numerical prediction and forecasting of reservoir performance rely on the knowledge of relative permeabilities. In gravity driven processes the flow is complex, consisting of co-current and counter-current flows. This work describes the characteristics of gravity driven flow and provides generalized permeabilities (or mobilities) for such flow. The results can be used in improved numerical simulation of gravity drainage processes. BACKGROUND The. standard multiphase relative permeability approach used in existing reservoir simulators is sufficient for describing steady state processes for either coor countercurrent flow. However, in the case of complex dueedimensional flow that combines both coand counter-current components, such as that in gravity drainage processes, transport coefficients have more complex form and should be addressed through matrix formulation. Furthermore, in the case of non-steady state counter-current flow in gravity drainage, the effective mobility becomes a more complex ftmction of steady state relative permeabilities and the staudard approach no longer represents the physics of the process accurately. During the last decade, new matrix formulation of phase mobilities has been extensively discussed in the literature. The theory is mature and its implementation is long overdue. The new momentum equations are a natural extension of the standard formulation with proper representation of crossinfhrences between flowing phases. The theory provides improved flow description as compared to the standard relative permeability concept in modelhng complicated nonsteady state processes such as gravity drainage. This is due to: 1. correct description of multiphase flows, 2. easy incorporation into existing multiphase simulators, 3. being a natural extension of existing standard relative permeability theory.

Coalescence Behavior of Water-in-Oil Emulsions

In this paper the use of electroacoustic techniques involving the application of a sonic field and the detection of an electric field, for monitoring coalescence of water droplets in non-polar media will be discussed. This technique was used to evaluate the rate and extent of dewatering in oil continuous emulsions when surface active chemicals were added. The results showed that a combination of an oil soluble demulsifier and water soluble surfactant was substantially more effective in causing droplet coalesence than the individual components. An explanation for these findings were based on studies of time-dependent interfacial tensions at the oil/water interface and electrokinetic properties. The results indicated that a direct relationship exists between the adsorption behavior at the oil/water interface (apparent rate of spreading) and emulsion stability.

A Physical Preventive Treatment of Crystallization and Precipitation in the Petroleum Industry

The plugging of tubings and pipelines by scale, asphaltene, and wax is a common problem in the oil production, transportation and refinery systems. Hot oiling, chemical wash and mechanical scraping have been used for many years to restore flow. There may be economic benefit to implement preventive treatments. We propose to consider the application of ultrasound as a potential preventive treatment. As a physical treatment, it is expected to be independent of the details of the chemical nature of the problem, i.e., it should be equally applicable to particles such as salt crystals, asphaltene precipitates, or wax. We will present experimental results showing the effects of application of ultrasound during precipitation and crystallization. Three systems were tested in this study; crystallization of salt from saturated aqueous solutions, re-dispersion of asphaltene in heptane, and pour point depression of diesel with different wax contents. The results show that, under the influence of ultrasound during the phase transition, there was a reduction of the size of the salt crystals, precipitated asphaltene was re-dispersed, and the temperature at the pour point of diesel with different wax contents was substantially lowered.