Species Distribution in Bicontinuous Phase Systems for Enhanced Oil Recovery Probed by Single-Sided NMR

Abstract

Multiphase aqueous-organic systems where a bicontinuous phase is in equilibrium with an excess organic and aqueous phase find various applications in industry. These systems�also known as Winsor III�are complex not only for the different phases that develop therein but also because they are multicomponent systems. In this work, we explore for the first time the use of a benchtop low-field single-sided NMR to determine the species distribution in Winsor III systems. The proposed methodology provides information at macroscopic and microscopic levels. In particular, we show the use of single-sided NMR to determine the phases' dimensions and the species distribution in a polymer-based bicontinuous system. The phases' dimensions and limits can be resolved with micrometric precision and are indicative of the bicontinuous phase stability. The species distribution is determined by means of spatially resolved NMR relaxation and diffusion experiments. It was observed that the salinity of the aqueous phase also impacts the species distribution in the bicontinuous system. Experiments show that the additive and the polymer are mainly located in the bicontinuous phase. As the salinity of the aqueous phase increases, the amount of organic components in the bicontinuous phase decreases as a consequence of the species distribution in the system. This influences the total amount of recovered organic liquid from the organic phase. The information is obtained in a relatively fast experiment and is relevant to the system's possible applications, such as enhanced oil recovery (EOR). This methodology is not only circumscribed to its application in EOR but can also be applied to the study of any emulsion or microemulsion systems without sample size or geometry constraints.

Effect of equilibration time on the structural gradient in the vertical direction for bicontinuous microemulsions in Winsor-III and -IV systems

“…This result is consistent with findings observed for BMEs using NMR. 3,22 For the other equilibration times, b is also lower in the middle of the bicontinuous phase as compared to the uppermost and lowermost vertical positions. Of interest is the agreement for b between equilibration times near the lower liquid-liquid interface.…”

“…Bicontinuous microemulsions (BMEs), consisting of thermodynamically stable nanodomains of water and oil separated by surfactant monolayers, are a unique medium potentially useful for many applications, such as enhanced oil recovery (EOR), [1][2][3] hosting enzyme reactions involving apolar substrates, 4 electrolytes for flow batteries, [5][6][7] templating media for nanomaterials, [8][9][10][11][12] and drug delivery vehicles. [13][14][15] BMEs composed of two immiscible polymers and AB-type block copolymers, the latter serving as surfactant, are employed as solid electrolytes for batteries and other materials.…”

“…The lower, water-bicontinuous phase liquid-liquid interface, possesses ultralow interfacial tension. 18 W III systems have been employed in EOR [1][2][3] and separations. 19,20 The systems correspond to the ''head'' region of the well-known ''fish'' phase diagrams, referring to the fishshaped phase boundaries for plots of surfactant concentration vs. tuning parameter (frequently temperature for alkyl ethoxylates and salinity for ionic surfactants) at a fixed water-oil ratio (typically near 1 w/w or v/v).…”

“…Two NMR-based studies found that water concentration increased and oil concentration decreased across the BME W III phase in the downward direction. 3,22 Previously, we investigated changes of structure of the bicontinuous phase of two W III systems via small-angle neutron scattering (SANS) at 1 mm vertical intervals through use of a vertical stage sample environment, which allowed for precise alignment of the bicontinuous phase in the vertical direction. 23 Through the analysis of SANS data, we found that the degree of ordering changed in the vertical direction but differently between W III systems and that the water concentration increased (oil concentration decreased) slightly in the downward vertical direction.…”

Analysis of Adsorbed Polyphosphate Changes on Milled Titanium Dioxide, Using Low-Field Relaxation NMR and Photoelectron Spectroscopy

“…Nuclear magnetic resonance (NMR) relaxometry is also proving to be an invaluable technique to study dispersion surface properties, or otherwise applied industrially to analyze pore structures and wettability in reservoir rocks for enhanced oil recovery, − where the use of very low-field, desktop instruments has provided an avenue for inline or at-line analysis. Originally, the technique was largely developed for rapid surface area measurements of nanoparticle dispersions , but has advanced extensively to incorporate analyses of a number of colloidal surface chemistry effects − and even nanobubbles .…”