Surfactant Behavior Analysis in Enhanced Oil Recovery Blends Using One-Dimensional Proton Nuclear Magnetic Resonance

Abstract

In this work, nuclear magnetic resonance (NMR) spectroscopy is used to investigate surfactant phase behavior relevant to chemical enhanced oil recovery. The effect of the solution electrical conductivity on the NMR signals was corrected using reference spectra of known conductivity. This allowed us to develop a semi-quantitative method to estimate the surfactant concentration by correlating it with either integrated NMR peaks or intensity of selected surfactant signal peaks. A distinct change in the slope of the assumed linear relationship between signal intensity and surfactant concentration was observed as the surfactant concentrations were increased. This was attributed to the progressive surfactant aggregation in solution. This result can be used as an alternative method to estimate the critical micelle concentration (CMC) of surfactants. NMR spectra were collected for individual surfactants and their combinations in a variety of saline aqueous solutions. Our results were compared to estimates obtained through more traditional ultraviolet–visible (UV–vis) spectroscopy and surface tension measurements. Consistency between NMR and surface tension estimates was found. CMC values determined through UV–vis were similar, although not quite the same as those of the other two techniques. Similarly, the NMR signals were used to estimate surfactant adsorption in the rock in the so-called static adsorption experiments, in which ground rock is exposed to a surfactant solution of known initial concentration. The results obtained show that NMR offers a powerful alternative to more frequently used methods to estimate not only CMC but also surfactant adsorption, particularly when multiple surfactants are present in aqueous solution.

Comprehensive review on surfactant adsorption on mineral surfaces in chemical enhanced oil recovery

“…148 A surfactant mixture, containing two or more surfactants, can be studied using solid-state proton nuclear magnetic resonance spectroscopy, either individually if there are unique peaks for each surfactant or all together if the peaks are overlapped. 149 Moreover, the total internal reflection Raman scattering (TIR Raman) and sum-frequency spectroscopy (SFS) have been employed to investigate the adsorption of CTAB on hydrophilic silica surface, and the average orientation and packing of the hydrocarbon chains of CTAB were irrelevant to surface coverages. 150 TIR Raman also explored adsorption and desorption kinetics of surfactants at the solid-liquid interface.…”

Interaction of Dendrimer-Based Polymer with Sodium Dodecyl Benzenesulfonate: Characterization and Effect on Properties of Composites

“…At the stage of low SDBS initial concentration, the surfactant molecule could be inclined to form mono layer adsorption until it reached an equilibrium state. With the continued increase of SDBS concentration, the free molecules and the absorbed molecules on the quartz sand surface developed surface micelles through the hydrophobic effect among hydrocarbon chains. ,, This resulted in a multilayer adsorption, so the adsorbance increased sharply. As saturation was produced for this adsorption behavior, the adsorbance of SDBS in the composite system leveled off.…”

“…The process involves adding some chemical agents to injected water to adjust the water/oil mobility ratio. − Among these agents, polymer can increase the viscosity of the displacing phase and reduce the permeability of the aqueous phase through appropriate adsorption and retention on the rock surface. ,− Thus, the polymer flooding can raise sweep efficiency observably, but it does nothing for displacement efficiency. On the contrary, surfactant flooding is able to lower the interfacial tension between oil and water and improve displacement efficiency effectively. ,, However, problems for surfactant flooding include low sweep efficiency, high cost, and excessive adsorption on the rock. − On the basis of the merits and shortages of polymer flooding and surfactant flooding, polymer/surfactant (SP) combinational flooding has been widely used in tertiary recovery. The technique promises both viscoelasticity and lower interfacial tension and can reduce the dosage of the surfactant. − Moreover, SP flooding overcomes the drawbacks of conventional alkali/polymer/surfactant (ASP) combination flooding technology, which involves reaction with divalent ions causing blockage of pipes, damage to equipment and impairment of the reservoir formation due to the addition of alkali. , …”

Composition to Interfacial Activity Relationship Approach of Petroleum Sulfonates by Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

“…Taber and Stegemeier investigated the relationship between residual oil and capillary number and observed that, when oil–water interfacial tension (IFT) reaches ultralow levels, oil displacement efficiency becomes very favorable. Ultralow IFT values are obtained using formulations able to develop microemulsion systems. − Moreover, it has been observed that these formulations must contain chemical species able to reduce the repulsion interactions between water and crude oil molecules and that these interactions can be considerably decreased when the surfactants employed within the formulations have similar chemical structures to those of the hydrocarbons present in the crude oil. , Recently, a surfactant behavior analysis in CEOR formulations has been proposed by means of one-dimensional proton nuclear magnetic resonance . Different works have focused independently on the effects of the branching, hydrophobicity, and interfacial properties of different surfactants, including petroleum sulfonates, on their performance.…”

“…13,14 Recently, a surfactant behavior analysis in CEOR formulations has been proposed by means of one-dimensional proton nuclear magnetic resonance. 15 Different works have focused independently on the effects of the branching, 16 hydrophobicity, 17 and interfacial properties 18 of different surfactants, including petroleum sulfonates, on their performance. However, an exhaustive compositional analysis of the surface-active species and their raw materials could help aide a rational design of a surfactant with the desired properties for CEOR and establish composition and performance relationships.…”