Chemical enhanced oil recovery (EOR) processes are usually used as additives for hydrocarbon production due to its simplicity and relatively reasonable additional production costs. Polymer flooding uses polymer solutions to increase oil recovery by decreasing the water/oil mobility ratio by increasing the viscosity of the displacing water. The commonly used synthetic water-soluble polymer in EOR application is partially hydrolyzed polyacrylamide (HPAM). However, synthetic polymers in general are not attractive because of high cost, environmental concerns, limitation in high temperature, and high-salinity environment. Guar gum is an environmentally friendly natural water-soluble polymer available in large quantities in many countries and widely used in various applications in the oil and gas industry especially in drilling fluids and hydraulic fracturing operations; however, very limited studies investigated on guar as a polymer for EOR and no any study investigated on its uses in high-temperature and high -salinity reservoirs. The objective of this study is to confirm the use of guar gum as a natural polymer for EOR applications in sandstone reservoirs and investigate its applicability for high-temperature and high-salinity reservoirs. The study experimentally investigated rheological characteristics of a natural polymer obtained from guar gum with consideration of high temperature (up to 210 °F) and high salinity (up to 20% NaCl) and tested the guar solution as EOR polymer. The results of this study show that the guar solution can be used as an environmentally friendly polymer to enhance oil recovery. Based on the results, it can be concluded that guar gum shows shear-thinning behavior and strongly susceptible to microbial degradation but also shows a very good properties stability in high temperature and salinity, where in low shear rate case, about 100 cp viscosity can be achieved at 210 °F for polymer prepared in deionized water. Guar polymer shows good viscosity in the presence of 20% NaCl where the viscosity is acceptable for temperature less than 190 °F. Also, the flooding experiment shows that the recovery factor can be increased by 16%.

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This paper deals with on line viscosity measurements using integrated circuit technology, and is building on a previous paper on the use radio frequency identifier (RFID) technology for determining dielectric coefficients. It is asserted that the progress in RFID technology and integrated circuits, in particular in micro–electro–mechanical system (MEMS) makes it possible to combine them to perform physico-chemical property measurements using devices on centimeter scale. It can even be expected that these devices can be made increasingly smaller. An important property of interest is the viscosity, in this specific case, for the use of Arabic gum in enhanced oil recovery. Arabic gum, is an environmentally acceptable natural product. Natural-polymer solutions 1000 [ppm] are more viscous and therefore more efficient oil displacement agents. They require less invested exergy than non-viscosified water to recover oil. However, polymers, in particular environmentally acceptable natural-polymers (e.g., Guar–Arabic gum) available in large quantities in India and Sudan, are susceptible to microbial degradation. It is therefore important to monitor its quality at the injection and production side for real-time quality control. Natural-polymers based on plant products are promising EOR agents. They may have a lower environmental footprint because of the biodegradability. To provide a proof of concept, we use a state of the art acoustic wave sensor (AWS), which can determine acoustic viscosities. It is asserted that RFID technology can be used to record the acoustic wave signal (SenGenuity vismart acoustic wave Sensor AWS) to determine the viscosity at some distance (meters) away from the measurement device. A calibration with solutions of known viscosity behavior (i.e., Glycerol) can be used to relate the acoustic viscosity to the dynamic viscosity. We can calibrate the acoustic wave sensor using Guar–Arabic gum solutions to measurements with the Anton Paar viscometer (MCR-302). For the glycerol solution we also compare to reported literature data. The Newtonian viscosity measurements of the Paar density meter, and the literature values agree within a few percent. These favorable comparisons, are an important step in developing a methodology that allows cutting edge RFID-IC technology for real-time non-contact monitoring of viscosity degradation.@en

It has been estimated that 17% of the recovered hydrocarbon exergy in oil fields [1]is spent on fluid handling and recovery costs. Therefore, improving the efficiency of oil production can give an some contribution to more efficient energy usage and therefore minimizing to some extent the carbon footprint. By way of example we present in this paper a work-flow, which can serve as a template for computing the fluid handling and recovery costs for natural polymer (Guar-Arabic Gum)flooding. The main contributors to the exergy investment in an Exergy Return on Exergy Investment analysis (ERoEI)are, the fluid circulation costs, the steel costs of the tubing and casing and to some degree the drilling costs. The main contributor to the exergy gain is the exergy of the produced oil. The fluid circulation costs represent the largest exergy investment and usually approximately accounts for 80% of the exergy used for the recovery of oil. For quantifying the circulation costs, the paper uses a 1-D displacement model of polymer flooding of oil to compare the enhanced oil recovery (EOR)history for three scenarios, i.e., (1)water injection, (2)natural-polymer water injection and (3)natural-polymer slug injection. The advantage of a 1-D model is that it allows multiple comparisons of many scenario's avoiding time consuming simulations but this goes at the expense of ignoring 3-D effects. The 1-D model can be extended to a 2-D or 3-D model, which makes it possible to include the improvement of vertical and areal sweep-efficiency. A numerical solution of the EOR model is obtained with COMSOL. We analyze the exergy balance of viscosified water, e.g., with natural-polymer. A comparison as to the displacement efficiency is made between the three scenarios, viz., water, Guar-Arabic gum, and slug injection. The viscosity behavior of Guar-Arabic gum is obtained from laboratory data. It is argued that an ERoEI analysis, which is used on its own or complementary to an economic analysis, can be used to show the advantage of using Guar-Arabic gum slugs with respect to permanent polymer-injection to enhance the oil recovery. Moreover, the analysis shows that at the end of the project, the concept of exergy-zero recovery time or zero-time marks, for each scenario the termination point, i.e., when the circulation exergy costs (exergy investment)become equal to the recovery exergy (exergy return), and thus recovery should be abandoned. For the conditions considered a single polymer injection displacement leads to optimal results.@en

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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