Recent developments in Radio Frequency (800 MHz–1000 MHz) Identification (RFID) devices suggest that it is possible to use them for wireless laboratory measurements of the dielectric coefficients (or compositions) of fluid mixtures with possible spin-off for their use in the petroleum engineering practice. The advantage of RFID devices is their small size (0.095×0.008×0.001 m³), the developments to make them increasingly smaller and that they do not require the use of leak prone connecting cables. RFID measures the response of a sample volume of interest irradiated by a radio frequency electromagnetic (EM) wave. The response can be expressed in terms of various response functions, e.g. two scattering functions (S₁₁ and S₂₁) or the minimum irradiated power (P_min). The response functions can be measured using a state-of-the-art RFID device (CISC RFID Xplorer-200), which operates in the range between 800 and 1000 MHz. The effect of the dielectric coefficient on the RFID response was tested by placing the RFID tag in different media with various dielectric coefficients ε ranging from 1 to 80. The overall purpose is to develop a work-flow to relate the response functions obtained with RFID technology to the dielectric coefficient and thus the composition of fluid mixtures in which an RFID tag can be immersed. An application is to measure fluid compositions during a spontaneous imbibition experiment in an Amott-cell. As an intermediate step we measure the composition dependence of the partial molar volume of diethyl ether (DEE) in brine and the partial molar volume of DEE in oil by using an Anton Paar density meter. The relation between the dielectric coefficients and the volume fraction can be obtained with the Böttcher mixing rule. The DEE volume fraction range of interest is 0–8% volume fraction in the aqueous solution whereas DEE volume fraction range of interest is 0–100% volume fraction in oleic solutions. For better understanding of the measurement results, we used COMSOL™ simulations, which show that the response functions depend on the dielectric coefficient in a vessel of appropriate dimensions filled with a fluid of choice. The measurements show that the minimum power at the tag position P_min is the preferred response function and that the sensitivity of P_min was highest at 915 and 868 MHz for aqueous (8.547×10⁻⁶) and oleic (1.905×10⁻⁴) solutions respectively. The measurement error is of the same order of magnitude as the errors mentioned above (Hon, 1989) ensuing from evaporation of DEE during the preparation of the calibration fluids or the approximate nature of the Böttcher mixing rule. We conclude that it is possible to use RFID technology for contact-less measurements of the compositions of fluids in imbibition experiments.

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Injection of dimethyl ether (DME) dissolved in water can enhance the recovery efficiency with respect to water flooding. In this Shell Proprietary Technology, DME partitions from water into the oil; decreases oil viscosity and increases its volume, and mobilizes the trapped oil again. In this work, DME-enhanced water flooding is combined with polymer and considered for cases in which a favorable mobility control between water and oil does not exist. In order to reduce the remaining oil, slugs of the mixed solution of DME and polymer were injected into the cores containing oil and then followed by injection of a chase fluid. This recovery method benefits both (a) from the presence of polymer, and the oil viscosity reduction caused by DME dissolution and (b) from oil swelling due to DME dissolution. It appears from experimental data that the injectivity of a DME/polymer (DMEP) solution is higher than the injectivity of a polymer solution without DME; this indicates the presence of DME can reduce the viscosifying effect of the polymer. The main experimental observations are: (1) a higher oil recovery is obtained from continuous DMEP flooding than from continuous DME-brine flooding, (2) the presence of polymer in the DME slug and in the chase phase reduced the remaining oil after a finite slug injection, and (3) a larger DME slug and mobility control of the chase phase can improve the oil recovery after a finite slug injection. In summary, the experiments show that combining polymer and DME improves the ultimate recovery significantly and shortens the duration of oil production.

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This paper presents a simple physical-based numerical model that simulates the surfactant-polymer (SP) flooding process for enhanced oil recovery (EOR). In this study, black-oil subsystems based on volume fraction balance was proposed for developing numerical model. The model was upgraded by taking into account different aspects of SP EOR process such as gravity effect, capillary pressure, mobility reduction factor, polymer/surfactant adsorption on rock and interfacial tension (IFT) reduction. The Langmuir isotherm coefficients for the adsorption of polymer and of surfactant were chosen from separately laboratory experiments of single component injection of surfactant and of polymer in the Bentheimer sandstone core. The systems of equations were solved in the Finite Elements based Method (FEM). The validity of the implementation was tested by comparing the results attained from simplified numerical model with laboratory core-flooding experimental data of SP flood into Bentheimer sandstone core. A comparison showed excellent agreement between the numerical results with the core flooding experimental results. This confirms that the developed numerical model in this work is robust and has capability to reproduce the main features of surfactant/polymer flooding (SP) EOR in the consolidated sandstone porous media. @en