Foam analysis at elevated pressures for EOR applications - Energy

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Foam analysis at elevated pressures for EOR applications Martina Szabries, Philip Tonio Jaeger, and Mohd M. Amro Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b03088 • Publication Date (Web): 21 Dec 2018 Downloaded from http://pubs.acs.org on December 24, 2018

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Foam analysis at elevated pressures for EOR applications Martina Szabries*α, Philip Jaegerβ, Moh’d M. Amroα αTechnical

University Bergakademie Freiberg, Institute of Drilling Engineering and Fluid

Mining, Agricolastraße 22, 09599 Freiberg, Germany βEurotechnica GmbH, An den Stücken 55, 22941 Bargteheide, Germany Keywords: Foam stability, foam structure, high pressure, CO2, N2, EOR, CO2-flooding

ABSTRACT

A novel foam analyzing system is presented in this work for systematical and scientifically based investigation of foaming capacity, structure and stability under process conditions relevant for enhanced oil recovery (EOR). The foam height as well as the foam structure are detected simultaneously as a function of foam age. The apparatus has an extended optical access by means of three tongue-shaped HP (high pressure)-windows. A special arrangement of prisms allows the detection of bubble shapes and size distribution at the same time. The results show a substantial difference of foams generated using compressed gases compared to atmospheric conditions. At pressures rising to 15 MPa, nitrogen foams become increasingly stable, while instable and metastable CO2-foams require a special selection of surfactants and foam stabilizers. Due to the higher

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solubility of CO2 in the film phase, Ostwald ripening and coalescence play an important role in decay of CO2-foams while these mechanisms are hardly observed in N2-foams.

1. INTRODUCTION The application of aqueous foam is increasingly discussed in enhanced oil recovery (EOR), combining different advantages of the pure substances and of the gas-in-liquid dispersion as complete system. Foam is able to improve the recovery by selective plugging of high permeability layers in heterogeneous reservoirs and by improving sweep efficiency (1). Using foam instead of pure gases, the mobility of the gas is reduced due to the higher apparent viscosity of the foam compared to the gas viscosity. (1, 2) Therefore the main challenges in gas flooding processes – namely gravity override and viscous fingering – are minimized (3), while the favorable effects of gas flooding still remain. In miscible and immiscible floods, the mass transfer between the gas phase and the crude oil can improve the recovery by reducing the oil viscosity, reducing the interfacial tension (IFT) between the reservoir fluids and swelling of the oil. (4) The surface active agents dissolved in the aqueous phase can improve the wettability (wettability alteration intermediate-wet to water-wet) of the reservoir rock, whereas the most important task of the surfactant molecules is to stabilize the foam during the flooding process. The application of foam in EOR can be combined with thermal methods like steam flooding assisted by foam (5,6) or insitu generated foams with simultaneous generation of heat by an exothermal reaction (7). In order to efficiently apply foams in EOR, the gas bubbles that are dispersed in the aqueous surfactant solution need to be stabilized. Different scientists examined added nanoparticles to stabilize CO2-foams (8,9,10,11). Before investigating the flow of stabilized gas-liquid-dispersions in porous media, the bulk behavior needs to be characterized for determining the influence of


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different process parameters on the structure and stability of the obtained foam. Apart from foamcore flooding experiments at HT/HP-conditions (high temperature / high pressure – conditions) (e.g. 12,13,14), experiments on foam behavior have only rarely been conducted at reservoir conditions, although pressure and temperature are known to play a relevant role in foam stability and bubble size distribution. Additional influencing factors are the type and concentration of the applied surfactant as well as the kind of gas. Different optical methods with often manually evaluation of the foam height exist and enable to observe the foam stability with time, whereas the foam structure is difficult to analyze under HP/HT-conditions, as multi-layers of bubbles complicate a two-dimensional analysis like the bubble size distribution. Therefore, a novel and extended foam analyzing system is presented in this work for systematical and scientifically based investigation of foaming capacity, structure and stability under real process conditions. The real-time foam height as well as the foam structure are detected simultaneously, enabling to relate both properties as a function of time. The apparatus has an extended optical access due to three tongue-shaped windows. A special arrangement of prisms allows a perfect detection of bubble shape of only one foam layer without any 3-D-disturbances. Foams for EOR application are mostly created with nitrogen or with carbon dioxide. The unique properties of supercritical carbon dioxide (scCO2), which are closely connected to a resulting low foam stability, lead to an increasing demand on extensive research on the mechanisms occurring inside a CO2-based foam and on different fluid properties like the mutual miscibility between the aqueous, the oil and the supercritical phase, as well as the IFT, the density and the viscosity of the different fluid phases inside the reservoir.


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2. EXPERIMENTAL METHODS A novel and extended foam analyzing system is developed and used in this study for systematical and scientifically based investigation of foam structure and stability under real process conditions of elevated pressure and temperatures up to 15 MPa at 45°C. The real-time foam height and its structure are detected simultaneously, enabling to relate both properties as a function of time. The apparatus has an extended optical access due to three high-pressure resistant tongue-shaped windows. The foam height is detected optically with transmitted light method (see figure 1 left) to receive the variable foam height depending on foam life. A special arrangement of prisms (see figure 1 right) allows a high-resolution detection of bubble shapes of a single 2-D-layer without disturbances from additional foam layers. A picture of the experimental set-up is depicted in figure 2.

Figure 1. Determination of foam height by transmitted light method (left) and determination of the foam structure of one single layer by a special arrangement of prisms (right) through pressureresistant tongue-shaped windows.


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Figure 2. Picture of the experimental set-up The foam is generated by sparging gas (CO2 or N2) into an aqueous surfactant solution through a sintered glass plate at the bottom of the device. As the bubble size depends not only on the IFT between the liquid and the gas, the gas flow rate and the density of the liquid phase but also on the pore sizes of the orifices for generating the bubbles, knowledge on the pore size distribution of the porous material is of vital importance especially in view of the real situation in the reservoir rock. The porosity and the pore size distribution are experimentally determined by mercury intrusion. The results are listed in table 1. Due to a synthetic manufacturing process, the pore size distribution of the used porous glass is even more homogenous than of natural rock material. Figure 3 shows the cumulative pore volume against pore size in logarithmic scale of the applied synthetic porous material compared to Bentheimer Sandstone.


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Table 1. Porosity and Pore sizes by mercury porosity measurements of the porous glass material. Porosity [%]

22,9

Pore size, arithmetic mean [m]

21,6

Pore size, median (D50) [m]

22,6

Pore size, D25 [m]

18,2

Pore size, D75 [m]

24,6


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Figure 3. Cumulative pore volume against pore diameter, logarithmic scale (mercury porosimetry), applied synthetic porous material compared to a natural sandstone. To prepare the set-up for the HP/HT-measurements, first the view cell is completely filled with aqueous surfactant solution through the top opening to avoid condensation on the windows during the subsequent heating of the device. After reaching a thermal equilibrium, the surfactant solution is drained off until only one-third of the observation-window is filled with the liquid. Then, the entire system is pressurized and saturated with the appropriate gas prior to the foam generation. Starting the foam generation, a volume of 100 ml gas is sparged through the porous plate at the bottom of the device (flowrate 50 ml/min). To avoid an increase of pressure during the foaming, a back pressure regulator is installed. During the foam decay, the system pressure is held constant.


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Additives like polymers (e.g. xanthan gum (XG)) or other foam stabilizers are dissolved in the aqueous surfactant solution before running the experiment. Each experiment is repeated at least twice under the same conditions (gas flow rate, pressure, temperature etc.) in order to ensure a good reproducibility. The repeatability of pressurized N2-foams is within +/- 6 % during the first 90 minutes. The repeatability of the shown CO2-foams is within +/- 10%. A schematic drawing of the foam device and the instrumental set-up is depicted in figure 4.

Figure 4. Schematic drawing of the high-pressure foam analyzer. A software has been designed specifically for this application (ADVANCE, Krüss, Germany). The whole process of foaming and collapse is recorded by video and analyzed. Each frame taken by the camera contains important information for the foam structure analysis regarding bubble shapes, liquid content and bubble size distribution (see figure 5).


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Figure 5. Pore size distribution, software: ADVANCE (Krüss, Germany). Accompanying experiments were carried out on the IFT at elevated pressures and temperatures by help of the pendant drop method using a high-pressure view cell (Pmax 69 MPa, Tmax 200°C, Eurotechnica, Germany) together with a drop shape analysis system (DSA100, Krüss, Germany) (15). The IFT gives important insight into the behavior of surfactants, especially their efficiency in terms of being accumulated at the interface and not only reducing the energy required to generate a high amount of surface but also increasing the surface elasticity. Additional material properties influencing the foam behavior are the dilatational elasticity (16), the density and the viscosity of the liquid phase (with dissolved gas) and the gas phase (partly with dissolved liquid and surfactant) (1). 3. RESULTS AND DISCUSSIONS The investigated aqueous foams were generated and stabilized with a non-ionic surfactant (Triton X®-100, Sigma Aldrich), 2 g/l demineralized water. The critical micelle concentration (cmc) at 25°C and ambient pressure is determined as 0.17 g/l by the Do Nouy-ring method (26). Since the cmc depends on the ratio of surface and bulk volume of the liquid inside the measurement vessel, on temperature, pressure and changes in presence of CO2, the cmc can only be used as a point of reference.


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3.1 FOAM STABILITY Regarding foam stability one has to differentiate between N2- and CO2-foams as the behavior is completely different. 3.1.1 STABILITY OF NITROGEN-FOAMS As expected, N2-foams show a much higher stability than CO2-foams (17,18). The foam stability of nitrogen-foams increases with increasing pressure in a pressure-range from atmospheric pressure up to 15 MPa (see figure 6). The foam partly collapses unevenly; holes and gaps are formed within a foam layer with advancing foam life time. Lunkenheimer (25) stated that the pressure shock resulting from a rupture of a single film led to an immediate rupture of neighboring cells, to explain the “stair-like” foam decay. In generally, the repeatability of the experiments strongly depends on foam life time. Within the first 90 minutes the repeatability of pressurized N2-foams is within +/- 6 %. It increases up to +/- 38% due to the described partly occurring unsteady foam decay.


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Figure 6. Foam stability of nitrogen foams, liquid phase: 2 g/L Triton®-X100 in demineralized water, gas phase: nitrogen, 45°C, foam generation with 100 mL nitrogen, flow-rate: 50 mL/min. Some reasons for a higher stability at enhanced pressure can be the generation of smaller bubbles (slowed Ostwald ripening and coalescence), more uniform bubble sizes (17) (reduced Ostwald ripening), the increase of the density and the viscosity of both phases (reduced drainage) accompanied by only a small increase of the generally low mutual solubility. It can be seen from figure 7, that the IFT between an aqueous solution of Triton® X-100 and nitrogen decreases with increasing pressure. A reduction of the IFT leads to an improved foamability, as the work required for the formation of the foam bubbles is reduced (19).


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Figure 7. Dynamic interfacial tension of nitrogen and an aqueous solution of Triton®X-100 (0.15 g/L demineralized water) at different pressures. 3.1.2 STABILITY OF CARBON DIOXIDE-FOAMS The analysis of the foam stability of CO2-foams is more complex. Compared to a measurement of the foam stability at ambient pressure, the foam stability first decreases with increasing pressure (see figure 8, ambient pressure compared to a CO2-foam at 2.5 MPa), whereas within the first minute the foam produced at ambient pressure shows a stronger decay than the foam generated with pressurized carbon dioxide. After one or two minutes, the behavior changes and the foam at ambient pressure remains more stable. In a pressure range of 2.5 to 7.5 MPa, the foam decay behavior is comparable among all tests within the first minutes. Beyond 7.5 MPa, the foam stability is lower at higher pressure. The comparison of foams at 7.5 MPa and foams at higher pressure up to 8.5 MPa reveal a


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strong change of the described behavior: The foam stability then is improved at higher pressure. It has to be highlighted, that these results were obtained using Triton® X-100 as foam-stabilizer and that they are only partly transferable to other surfactant-systems. In accordance to our results, Wang (20) stated, that the stability of CO2-bulk-foams increases with increasing pressure within an pressure range from 6.9 to 13.8 MPa using Alipal CD128 as surfactant. In contrary to our results, Farzaneh (21) supposed that the influence of pressure is neglectible at surfactant concentrations above the cmc, wheras different authors underline the pressure dependance of CO2-foams (22,23). In a pressure range between 5.5 and 13.8 MPa Liu (24) presented a continuously decreasing CO2-bulk-foam stability with increasing pressure using the surfactant Chaser CD1045. Using core flood experiments, Solbakken (13) showed that with increasing pressure above 9 MPa, the foam stability of CO2-foams decreases. Comparing the foam strength at pressures of 3, 12 an 28 MPa leaded to the same results: The strength of CO2-foams defined by the mobility reduction factor MRF decreases with increasing pressure (17) using an anionic AOS surfactant. Aarra (14) concluded that in general CO2-foams are stronger than N2-foams and that strong CO2foams are generated when CO2 was in gaseous state and weaker foams were generated when CO2 was in supercritical state (above 7.375 MPa and 30.98 °C). Shokrollahi (18) showed at atmospheric pressure, that N2-bulk-foams stabilized with Triton® X-100 are more stable than comparable CO2-foams. Li (22) presented, that the stability of CO2-bulkfoams increases with increasing pressure in a pressure range between 2 and 12 MPa using SDS as surfactant. Li explained this behavior with an dramatically increase of the CO2density and the viscoelastic modulus and a declining IFT with increasing pressure. An overview of the described results of different studies an foam behavior are listed in table


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2. It can be seen, that the comparability is difficult because of many existing parameters like the method, the kind of surfactant, concentration, temperature and pressure influencing the results about foam behavior. On the other hand, the demand on research on foam behavior at reservoir conditions can be seen as well.

Figure 8. Foam stability of carbon dioxide foams, liquid phase: 2 g/L Triton®-X100 in demineralized water, gas phase: carbon dioxide, 45°C, foam generation with 100 mL CO2, flowrate: 50 mL/min.


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Table 2. Comparison of the results of different CO2-foam behavior-studies. Author

Gasphase

Surfactant

concentration

Temp.

Pressure

Method

Foam behavior

Li et al. (2016) (22)

CO2

SDS (anionic)

0.25 wt%

22°C /40°C

2-12 MPa

Bulk

Stability increases with increasing pressure

Wang (1984) (20)

CO2

Alipal 128 ionic)

CD(non-

0.1, 0.5, 1.0 and 2.0 vol.%

24°C

6.9-13.8 MPa

Bulk


Alkan et al. (1991) (2)

CO2

O-SAP, N-40, CD-128, PAI, S-50, C-10

0.1, 0.2, 0.3, 0.5, 1 vol.%

65°C

atmospheric pressure, 5.8 MPa

Bulk


Liu et al. (2005) (24)

CO2

Chaser CD1045

˂˂ cmc

25°C

5.5-13.8 MPa

Bulk

Stability decreases with increasing pressure

Liu et al. (2005) (24)

CO2

Chaser CD1045

≤ cmc

25°C

5.5-13.8 MPa

Bulk

Stable over 100 min (independent of pressure)

Solbakken et al. (2013, 2015) (13,17)

CO2

AOS (anionic)

0.5 wt.%

50°C

3-28 MPa

Core, MRF


Solbakken et al. (2013) (13)

CO2

AOS (anionic)

0.5 wt.%

90°C

9-12 MPa

Core, MRF


This studies

CO2

Triton X-100 (non-ionic)

˃ cmc

45°C

0-7.5 MPa

Bulk


This studies

CO2

Triton X-100 (non-ionic)

˃ cmc

45°C

7.5-9 MPa

Bulk


Within the complete pressure range examined in this study (ambient pressure up to 8.5 MPa), the density of both phases increases with increasing pressure. The density of the pure phases without any mass transfer of single components continuously increases with increasing pressure. Additonally, the dissolution of carbon dioxide into the aqueous phase leads to a further increase


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of the density. At pressures above the critical point, the surfactant molecules are partly dissolved in the gas phase. As a consequence, the density of the gas phase is further enhanced. This “extraction effect” leads to a reduction of surface active agents in the aqueous phase and therefore to a lack of surfactants contributing to stabilization of the foam lamellae. The latter effect can be proved by pendant drop measurements of the dynamic IFT between aqueous solution of Triton®X100 and CO2 at different pressure (see figure 9). At moderate pressures, the IFT decreases with drop age, reaching a constant minimum. At a pressure of 10 MPa, the IFT increases after having passed a minimum, because of the described “extraction effect”. As a consequence, the concentration of surfactants at the interface is reduced.

Figure 9. Dynamic interfacial tension of carbon dioxide and an aqueous solution of Triton®X100 (0.2 g/L demineralized water) at different pressures.


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3.1.3 COMPARISON FOAM STABILITY OF N2- VS. CO2-FOAMS The half-life-time is a common parameter to characterize thermodynamically instable systems and therefore often used to compare foam stabilities. In case of stable foams like nitrogen-foams at enhanced pressure, the half-life-time is an appropriate parameter (see figure 10). In case of instable or meta-stable CO2-foams, the half-life-time method is not sufficient to represent the foam behavior in detail. Lunkenheimer (24) proposed a parameter named R5. R5 is the ratio of the foam height at a foam life of 5 minutes and the initial foam height multiplied with 100:

𝑅5 =

ℎ5 ℎ0

∗ 100

R5-values of the presented N2- and CO2-foams are depicted in figure 11. The behavior of the meta-stable CO2-foams is well expressed by this parameter, whereas for stable N2-foams this shorttime value does not make sense. Using the R5-parameter could give the impression, that there is no pressure dependence of the foam stability of foams created with nitrogen. In case of long-term stability foams, the parameter should use a foam height of minimum one hour compared to the initial foam height. It can be seen from figure 12 that the behavior of N2-foams is well characterized by the relation of the foam height at a foam-life-time of 60 minutes compared to the initial foam height. In case of CO2-foams the R60-value is “zero” at any pressure, because of the strong decline of the foam height with time.


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Figure 10. Half life time as a function of pressure, foam liquid phase: 2 g/L Triton®-X100 in demineralized water, foam gas phase: nitrogen or carbon dioxide, 45°C, foam generation with 100 mL gas, flow-rate: 50 mL/min.


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Figure 11. R5-parameter ((Foam height (5 min) / initial foam height)*100) as a function of pressure, foam liquid phase: 2 g/L Triton®-X100 in demineralized water, foam gas phase: nitrogen or carbon dioxide, 45°C, foam generation with 100 mL gas, flow-rate: 50 mL/min.


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Figure 12. R60-parameter ((Foam height (60 min) / initial foam height)*100) as a function of pressure, foam liquid phase: 2 g/L Triton®-X100 in demineralized water, foam gas phase: nitrogen or carbon dioxide, 45°C, foam generation with 100 mL gas, flow-rate: 50 mL/min. 3.1.4 FOAMS STABILIZED WITH XANTHAN GUM (XG) CO2-foams can be stabilized by adding polymers like XG. The relative foam heights of a foam at 5 MPa created with an aqueous solution of Triton® X-100 (2 g/l demineralized water) and a comparable foam with added XG (2 g/l demineralized water) compared with a foam stabilized with Triton® X-100 (2 g/l demineralized water without XG) and generated using nitrogen are depicted in figure 13.


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Figure 13. Foam stability of carbon dioxide foams, liquid phase: 2 g/L Triton®-X100 in demineralized water and 2 g/L Triton®-X100 in demineralized water + 2g/L XG, gas phase: carbon dioxide, 45°C, foam generation with 100 mL CO2, flow-rate: 50 mL/min. The density of the pure liquid (aqueous solution of Triton® X-100) increases marginally with added XG (see figure 14). The viscosity of pure water and aqueous solutions of Triton® X-100 does not exceed single-digit values (cP) (28, 29) in the investigated temperature and pressure range of 25 to 45° C and ambient to 5 MPa. The viscosity of XG-solutions (2 g/L) at 25°C and ambient pressure (2 g/L) is measured to 1100 cP at low shear rates of 0.3 s-1 by Zhong (30). Although the viscosity of aqueous XG solutions decreases slightly with increasing pressure and temperature, the viscosity of the continuous liquid phase containing XG is somewhat higher than without added


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polymer. As a result, the drainage and the mass transfer of CO2 is reduced leading to a higher foam stability.

Figure 14. Liquid densities of aqueous solutions (HP/HT-densitometer DMA-HP, Anton Paar, Gemany) 3.2 FOAM STRUCTURE The effect of pressure on the mean bubble area is similar in case of N2- as in case of CO2-foams. At higher pressure, the foam bubbles are reduced in size. The initial mean bubble area is merely a function of pressure and independent of the applied gas. However the change of the mean bubble area during foam life strongly depends on the physical and chemical properties of the gas: The mean bubble area of a N2-foam and a CO2-foam at 5 MPa (same experimental conditions: gas flow rate during foaming, total volume of gas and temperature) are compared in figure 15. Furthermore,


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figure 15 shows the comparison to a CO2-foam additionally stabilized with XG. The CO2-foam shows a sharp increase of the mean bubble area by time whereas the mean bubble area of the N2foam increases relatively slowly. A moderate increase of the mean bubble area is associated to a high foam stability. The more stable the foam (see figure 13) the lower the gradient of the mean bubble area with time (see figure 15).

Figure 15. Mean bubble area (MBA) of different foams, 45°C, foam generation with 100 mL gas, flow-rate: 50 mL/min. While the initial mean bubble area is similar in case of different liquid and gas phases, foams additionally stabilized by XG are much wetter than the comparable foams without polymer (see fig. 16). After 5 minutes of foam age the heterogeneity increases in the order from N2-, CO2/XG-


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to CO2-foams. At a foam age of 20 minutes, the CO2-foam without polymer is completely collapsed. N2- foams are still more homogenous than CO2-foam stabilized with additional XG. A homogenous bubble size distribution reduces disproportion and thereby leads to an increased foam stability.

Figure 16. Images of the structure of different foams with time, 5 MPa, 45°C 4. CONCLUSIONS Based on the presented experimental results of foam stability and foam structure at elevated pressures using Triton® X-100-stabilized foams, the following conclusions can be drawn: 

Stability and structure of liquid foams at elevated gas pressures differ substantially from these properties under atmospheric conditions


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

Foams generated with compressed nitrogen are stable over several hours due to the higher gas density, stronger surfactant interactions at the interface while gas diffusion is still low. Foam stability increases with increasing pressure.

 Foams generated with compressed carbon dioxide are much weaker than nitrogen-foams as carbon dioxide is soluble in the liquid film phase to a higher extent which leads to a pronounced Ostwald ripening and coalescence.  The principal effect of pressure on the initial bubble size is similar for both gases (CO2 and N2)  The IFT may be used to explain the foam behavior. The low IFT in case of CO2 reflects the strong mutual miscibility that counteracts foam stability in spite of the reduced amount of energy for generating new interface.  When selecting appropriate surfactants, the solvent power of compressed CO2 for some classes of surfactants needs to be taken into account because these surfactants will be withdrawn from the interface and subsequently will lose their stabilizing effect.  Enhanced viscosity of the liquid phase leads to an improved foam stability due to a reduced drainage and a reduced gas diffusion. As a consequence regarding EOR applications, it may be stated that the elevated pressure required for obtaining miscibility effects and mobilizing the oil within the reservoir is advantageous for stabilizing the foam inside the pores at the same time. In this way, the potential of foam generated with compressed gases could be demonstrated. Nevertheless, wetting properties on the inner pore walls will need to be taken into account for the film


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drainage. In (27) a strongly competitive wetting between CO2 and an aqueous solution was found leading to contact angles close to 90° for sand stones which would suggest to have a neutral effect on the drainage in this case. In case of strongly water wet surfaces, film drainage may be accelerated. Anyway, this point will need to be subject to future investigation. Another subject of further research with respect to application in EOR should be the influence of dissolved salts on HP/HT bulk foam properties. In order to explain foaming behavior at elevated pressures in more detail and select appropriate surfactants, dynamic IFT measurements under reservoir conditions are strongly recommended. In future oscillating pendant drop measurements are planned to complement foam testing in this respect. ACKNOLEDGEMENTS We sincerely thank the whole team working on foams from Krüss GmbH in Hamburg, Germany, for the software development and the continuous technical and IT support. REFERENCES (1) Stevenson, P. (ed.) (2012): Foam Engineering, Fundamentals and Applications, Wiley (2) Alkan, H.; Goktekin, A.; Satman, A. (1991): A Laboratory Study of CO2-Foam Process for Bati Raman Field, Turkey. In: Middle East Oil Show. Middle East Oil Show. Bahrain, 1991-11-16: Society of Petroleum Engineers (3) Talebian, Seyedeh, H.; Masoudi, Rahim; Tan, Isa M.; Zitha, Pacelli L.H.: Foam assisted CO2-EOR; Concepts, Challenges and Applications. In: SPE Enhanced Oil Recovery Conference. Kuala Lumpur, Malaysia: Society of Petroleum Engineers. (4) Lake, L.W.; Johns, R.; Rossen, B.(2014): Fundamentals of Enhanced Oil Recovery. Richardson: SPE. (5) Barnewold, D. (1998): Untersuchungen zur Schaumstabilität von Tensiden in porösem Gestein zur Verbesserung des Entölungsgrades beim Dampffluten. Aachen, Techn. Hochsch., Diss., 1998


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Energy & Fuels

(6) Lemanowicz, I. (1995): Tertiäre Erdölförderung, Dampf-Fluten mit mobilitätsreduzierenden Tensidschäumen. Zugl.: Aachen, Techn. Hochsch., Diss., 1995. Als Ms. gedr. Aachen: Shaker (Berichte aus dem Institut für Eisenhüttenkunde, 95,13). (7) Wang, F.; Chen, H,; Alzobaidi, S.; Li, Z. Application and Mechanisms of Self-Generated Heat Foam for Enhanced Oil Recovery. Energy Fuels 2018 (8) Emrani, A.S.; Nasr-El-Din, H.A. (2017): Stabilizing CO2 Foam by Use of Nanoparticles. In: SPE Journal 22 (02), S. 494–504. (9) Worthen, A. J.; Bryant, S.L.; Huh, C.; Johnston, K. P. (2013): Carbon dioxide-in-water foams stabilized with nanoparticles and surfactant acting in synergy. In: AIChE J. 59 (9), S. 3490–3501. (10) Ibrahim, A. F.; Emrani, A.; Nasr-El-Din, H. (2017): Stabilized CO2 Foam for EOR Applications. In: Carbon Management Technology Conference. Carbon Management Technology Conference. Houston, Texas, USA, 2017-07-17: Carbon Management Technology Conference. (11) Espinoza, D. A.; Caldelas, F. M.; Johnston, K. P.; Bryant, S.L.; Huh, C. (2010): Nanoparticle-Stabilized Supercritical CO2 Foams for Potential Mobility Control Applications. In: SPE Improved Oil Recovery Symposium. SPE Improved Oil Recovery Symposium. Tulsa, Oklahoma, USA, 2010-04-24: Society of Petroleum Engineers. (12) Andrianov, A.; Farajzadeh, R.; Mahmoodi Nick, M.; Talanana, M.; Zitha, P. L. J. (2012): Immiscible Foam for Enhancing Oil Recovery: Bulk and Porous Media Experiments. In: Ind. Eng. Chem. Res. 51 (5), S. 2214–2226 (13) Solbakken, J.; Skauge, A.; Aarra, M. G. (2013): Supercritical CO2 Foam - The Importance of CO2 Density on Foams Performance. In: SPE Enhanced Oil Recovery Conference. SPE Enhanced Oil Recovery Conference. Kuala Lumpur, Malaysia, 201307-02: Society of Petroleum Engineers. (14) Aarra, M. G.; Skauge, A.; Solbakken, J.; Ormehaug, P. A. (2014): Properties of N2- and CO2-foams as a function of pressure. In: Journal of Petroleum Science and Engineering 116, S. 72–80. (15) Jaeger, P. T.; Eggers, R. (2012): Interfacial properties at elevated pressures in reservoir systems containing compressed or supercritical carbon dioxide. PuIn: The Journal of Supercritical Fluids 66, S. 80–85. (16) Pugh, R.J.: Bubble and Foam Chemistry, Cambridge University Press, 2016 (17) Solbakken, J. S.: Experimental Studies of N2- and CO2-Foam Properties in Relation to Enhanced Oil Recovery, Dissertation, University of Bergen, Norway, 2015 (18) Shokrollahi, A.; Ghazanfari, M. H.; Badakhshan, A. (2014): Application of foam floods for enhancing heavy oil recovery through stability analysis and core flood experiments. In: Can. J. Chem. Eng. 92 (11), S. 1975–1987.


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(19) Myers, D. (1991): Surfaces, interfaces, and colloids. Principles and applications. Weinheim u.a.: VCH. (20) Wang, G. C. (1984): A Laboratory Study of CO2 Foam Properties and Displacement Mechanism. In: SPE Enhanced Oil Recovery Symposium. SPE Enhanced Oil Recovery Symposium. Tulsa, Oklahoma, 1984-04-15: Society of Petroleum Engineers. (21) Farzaneh, S. A.; Sohrabi, M. S. (2014): Alkaline assisted CO2-foam for improving heavy oil recovery. In:. International Petroleum Technology Conference: Society of Petroleum Engineers, S. 909–925. (22) Li, S.; Li, Z.; Wang, P. (2016): Experimental Study of the Stabilization of CO2 Foam by Sodium Dodecyl Sulfate and Hydrophobic Nanoparticles. In: Ind. Eng. Chem. Res. 55 (5), S. 1243–1253. (23) Du, D.; Beni, A. N.; Farajzadeh, R.; Zitha, P. L. J. (2008): Effect of Water Solubility on Carbon Dioxide Foam Flow in Porous Media: An X-ray Computed Tomography Study. In: Ind. Eng. Chem. Res. 47 (16), S. 6298–6306. (24) Liu, Y.; Grigg, R. B.; Svec, R. K. (2005): CO2 Foam Behavior: Influence of Temperature, Pressure, and Concentration of Surfactant. In: SPE Production Operations Symposium. SPE Production Operations Symposium. Oklahoma City, Oklahoma, 200504-16: Society of Petroleum Engineers. (25) Lunkenheimer, K.; Malysa, K. (2003): Simple and generally applicable method of determination and evaluation of foam; . In: J Surfact Deterg 6 (1), S. 69–74. (26) Harkins, D.W.; Jordan, H.F.(1930): A method for the determination of surface and interfacial tension form the maximum pull on a ring; Journal of American Chemical Society 1930 52 (5), 1751-1772 (27) Wang, J.; Ryan, D., Szabries, M., Jaeger, P. (2018): A study for using CO2 to enhance natural gas recovery from tight reservoirs, Energy and Fuels, submitted for publication. (28) NIST chemistry webbook, https://webbook.nist.gov/chemistry/fluid (29) Dittmar, D.: Untersuchungen zum Stofftransport über Fluid/Flüssig Phasengrenzen in Systemen unter erhöhten Drücken, Shaker Verlag, Aachen 2008 (30) Zhong, L.; Oostrom, M.; Truex, M.J.; Vermeul, V.R., Szecsody, J.E.: Rheological behavior of xanthan gum solution related to shear thinning fluid delivery for subsurface remediation, Journal of Hazardous Materials, 244-245 (2013) 160-170


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Corresponding Author *Martina Szabries, Institute of Drilling Engineering and Fluid Mining, Technical University Bergakademie Freiberg, Agricolastraße 22, 09599 Freiberg, Germany, [email protected] Author Contributions The manuscript was written through contributions of all authors. All authors have given approval to the final version of the manuscript.


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Foam analysis at elevated pressures for EOR applications - Energy

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