Viscometer for Opaque, Sealed Microemulsion Samples

Abstract

Formulation of surfactant EOR systems usually involves multiple salinity scans of the phase behavior of crude oil, surfactant, and brine systems. Usually, the measurements are made in sealed pipettes for accurate volume measurements without fluid loss. The volumes of oil and water solubilized into the microemulsion phase are observed to determine the optimal salinity and estimate the interfacial tension. Viscous emulsions and surfactant-rich condensed phases are not desirable. However, the only estimate of viscosity from the salinity scans is the movement (or lack of movement) of the interfaces upon tilting of the tube. A falling-sphere viscometer with multiple, ring-shaped, inductive proximity sensors is described. The device uses 0.78 mm, gold-coated, paramagnetic, 440 stainless steel spheres. With this size sphere, it is possible to accurately estimate the viscosity of fluids from 1 to 1,200 cp. The spheres are paramagnetic, so they can be lifted to the top of the tube with a magnet, and meet the constraints of a Reynolds number less than 800 for low viscosity fluids, and a velocity fast enough to be detected for a high viscosity fluid. A data acquisition system control a set of four sensors for signal conditioning and time recording. When the same phase spans the space between a pair of sensors, its viscosity can be estimated directly from the transit time of the sphere. When two or three phases span the space between a pair of sensors, the viscosity of the undetermined phase can be estimated from the transit time across it after correcting for the transit times across the upper and/or lower phases. Thus the viscosity of a middle-phase microemulsion can be estimated even if it spans only a small fraction of the distance between sensors. The system has been used to measure viscosities of lower-, middle-, and upper-phase microemulsions at ambient temperature. Also, apparent viscosities of macroemulsions and of the "colloidal dispersion" layer at the top of a lower-phase microemulsion have been measured.

Assessment of a surfactant- polymer formulation for conditions in a Colombian field

“…A similar behavior was reported [34], [35]. Also, the micro-emulsion viscosity behavior shows local minimum near to the optimal salinity, as proposed by other authors [34]- [36]. We interpreted it as a check of the behavior elucidated and the criteria proposed.…”

“…They also proposed that the birefringence and viscosity are maximized near the salinity that a transition of phase behavior occurs. Similarly, Lopez Salinas [36] performed the micro-emulsion viscosity measurements using a falling-viscometer with multiple ring-shaped and inductive proximity sensors. The micro-emulsion viscosity presented a Newtonian behavior.…”

A systematic approach to alkaline-surfactant-foam flooding of heavy oil: microfluidic assessment with a novel phase-behavior viscosity map

“…One indication that chemical equilibration was reached after two weeks was the agreement with trends of previous work 39 . After the samples physically equilibrated for 410 days, the apparent viscosity of the upper-oleic layer was measured in situ via falling sphere viscometry 46 . (See Supplementary Text S2 for more details about equilibration.)…”

Design of a Robust ASP Formulation for Clay Rich and Moderate Permeability Sandstone Reservoir: From Laboratory to Single Well Chemical Tracer Test in the Field

“…The viscosity of type III microemulsion can have a significant effect on the transport of generated oil bank in porous media during a coreflood (Gogarty et al 1970). The viscosity of the type III microemulsion phase was measured using a falling sphere viscometer (Lopez-Salinas et al 2009). Figure 7 shows the viscosity of type III microemulsion phases observed for various formulations during the phase behavior screening tests.…”