Synergistic Effects of Ionic Characteristics of Surfactants on Aqueous

Article pubs.acs.org/IECR

Synergistic Effects of Ionic Characteristics of Surfactants on Aqueous Foam Stability, Gel Strength, and Rheology in the Presence of Neutral Polymer Amit Saxena, A. K. Pathak, and Keka Ojha* Department of Petroleum Engineering, Indian School of Mines, Dhanbad, Jharkhand 826004, India ABSTRACT: Foam fluid, the new domain for drilling unconventional reservoirs, is facing challenges before being implemented in the drilling industry because of its complex nature under dynamic borehole conditions. Its compressible nature makes the study of its rheology a complicated affair. Rheology helps in the design of an efficient drilling fluid, which depends on various other variables. In the present study, foams of variable quality were prepared from a base fluid consisting of surfactant and polymer in water. The stability, quality, and rheological behavior of the foams were observed to vary with the ionic characteristics of the surfactant, quality of the foam, and concentration of chemicals added to the base fluid. The microscopic structure of the foams reflected the variations in the foam structure with changes in different variables.

1. INTRODUCTION With the need for the exploration of naturally fractured reservoirs, tight reservoirs, coal-bed methane (CBM), and shale-gas reservoirs, the development of underbalanced drilling techniques has become inevitable. When the hydrostatic head of a drilling fluid is intentionally designed to be lower than the pressure of the formation being drilled, the operation is considered underbalanced drilling.1,2 Foam-based drilling is one of the most promising techniques in this category. In this process, foam is used as a drilling fluid, as it has a cutting carrying capability approximately 10 times higher than that of conventional drilling fluids.3,4 Moreover, foam is primarily preferred because of its ability to eliminate formation damage, lost circulation, differential sticking, and other drilling-associated problems. Foam fluids are basically composed of a surface-active agent dissolved in an aqueous solution or in any other base fluid.1,5,6 Foam is thermodynamically unstable in nature, where stability generally refers to lifetime. Stable foam, which has a longer lifetime, is a mixture of air, water, and surfactant (soap). It is prepared by the introduction of a pressurized stream of fluid into a base fluid. The base fluid is prepared by adding a known concentration of surfactant in water or any other fluid. Unlike for incompressible fluids, absolute pressure affects foam rheology and pressure losses of foam flow with a given foam quality. Pressure increases foam shear stress and apparent viscosity at a given shear rate.7 Adding polymer to aqueous foam significantly increases the apparent foam viscosity.8 When a jet of air, nitrogen, or carbon dioxide is introduced into this fluid system, an emulsion is formed in which the gas is entrapped inside the surfactant film, forming a continuous phase.9 The addition of the polymers is used to alter the viscosity pattern of the system and to ensure the stability of the interface film. The effect of polymer on viscosity is governed by the ionic groups of the surfactant and polymer present in the system.10 Polymers such as guar gum and xanthan gum are used as stabilizing and viscosity-altering chemicals. Foam is known for its versatility when used under underbalanced conditions. © 2014 American Chemical Society

However, foam drilling is still an emerging technology and needs more attention before being applied to industry. For use in drilling wells, characterization of this fluid is of prime importance. Control of foam quality and rheology during circulation is considered to be one of the key parameters in successful drilling. It is necessary to find the optimum foam quality with desired characteristics that will allow successful drilling in underbalanced wells.11−13 Foam quality can be defined as the fraction of foam in the total bulk volume, that is the volume of the foam divided by the total volume of the foam and the liquid. A foam quality of greater than 70% and less than 95% is suitable for use as a drilling fluid.14 The behavior of foam can be described by a power-law model, and its viscosity can be predicted on the basis of experimental results. The power law provides a good description of fluid behavior across the range of shear rates to which the coefficients were fitted. It is given by the equation ⎛ ∂u ⎞n − 1 μeff = k ⎜ ⎟ ⎝ ∂y ⎠

(1)

where ueff is the effective viscosity, k is the consistency index, and n is the flow behavior index of the fluid. The consistency index (k) is defined as the viscosity at a shear rate of 1 s−1, and the behavior index (n) indicates the degree of shear thinning. The lower the value of n, the greater the shear-thinning characteristics. It describes three models: (1) pseudoplastic, n < 1, where the effective viscosity decreases with shear rate; (2) Newtonian, n = 1, where viscosity does not change with shear rate; and (3) dilatant, n > 1, where effective viscosity increases with shear rate. Although foam-based fluids provide better responses in terms of formation damage, cutting suspensions, and so on, the Received: Revised: Accepted: Published: 19184

July 1, 2014 November 13, 2014 November 20, 2014 November 20, 2014 dx.doi.org/10.1021/ie502598s | Ind. Eng. Chem. Res. 2014, 53, 19184−19191

Industrial & Engineering Chemistry Research

Article

rheology of these fluids is unpredictable in most cases. They also exhibit high fluid loss characteristics. Hence, before field applications, a thorough investigation of the rheology of foambased drilling fluids is needed. In this article, an intensive study of the rheological behaviors of foams produced using the anionic surfactant sodium dodecyl sulfate (SDS), the cationic surfactant hexadecyltrimethylammonium bromide (CTAB), and the neutral surfactant polyoxyethylene (20) stearyl ether (Brij S20) was carried out. The effect of the addition of polymer (guar) on the properties of the resulting foams was also studied.

2. MATERIALS AND METHODS 2.1. Materials. Different chemicals used for the present investigation were of high purity (>99.5%) and were used without further treatment. The anionic surfactant SDS was purchased from Fisher Scientific, Mumbai, India. CTAB and Brij S20 were obtained from Acros Organic, Geel, Belgium. The polymer used in the present study, guar gum, was obtained from Otto Kemi, Mumbai, India. Potassium chloride (KCl) was purchased from Qualigens Chemicals Pvt. Ltd., Mumbai, India. 2.2. Methods. 2.2.1. Preparation of Foam Fluid and Measurement of Its Quality. Foam was prepared in brine solution at varying polymer and surfactant concentrations. First, 1 wt % KCl was dissolved in distilled water, and then the required amounts of surfactants and polymers were mixed with this brine solution. The mixture was then stirred for 5 min with a mechanical stirrer at a controlled speed of 200 rpm (rotations per minute) to make it homogeneous. In the next step, the speed of the stirrer was increased to 4000 rpm and maintained at this level for a period until the desired quality of foam was obtained. The foam quality was measured with a 250 mL measuring cylinder. After preparation, 200 mL of foam was taken into the cylinder, and the drained liquid volume was measured. From these volumes, the foam quality was determined according to the definition mentioned above. Figure 1 depicts the steps of the foam preparation process. The temperature of the system was maintained at 30 °C for the entire study. 2.2.2. Half-Life Time. Half-life time, which indicates the stability of foam and hence the working time, was determined by observing the change in the height of foam with time.15,16 The prepared foam was immediately poured into a 1000 mL measuring cylinder that was kept inside a water bath maintained at 30 °C. When the foam was exposed to the local atmosphere, the bubbles started to coalesce, and the foam height started to decrease. The height of the foam was examined continuously, and the time at which the foam height was reduced by half was noted as the half-life time in minutes. The thermal stability of the foam was also investigated by observing the change in foam quality as a function of temperature. 2.2.3. Observation of Foam Microstructure. The size distribution of the freshly prepared foam was observed by high-resolution polarizing microscopy (Olympus UC 30) at a 4× zoom at different time intervals varying between 0 and 30 min after preparation. Image analysis software was used to determine the areas of bubbles. The mean radii of the foams at different time intervals were determined and reported as the variation in bubble structure. 2.2.4. Determination of Gel Strength and Viscosity. A Fann VG viscometer (model 35 SA) with the ability to perform assays at six different speeds ranging from 3 to 600 rpm was used in the determination of foam viscosity and gel strength.

Figure 1. Flowchart for the preparation of foam.

To select the desired speed, the switch located on the right side of the base was set to the high- or low-speed position as desired. Then, the motor was turned on, and the viscometer gear-shift knob located in the center of the top of the instrument was moved to the desired position. A total of 450 mL of freshly prepared foam was taken each time for the entire study using this instrument. The apparent viscosity was measured at 600 rpm. For rheological analysis, readings were taken at (30 ± 1) °C at different shear rates.

3. RESULTS AND DISCUSSION 3.1. Foam Quality, Microscopic Structure, and HalfLife Time. Accurate determination of the foam texture and gas−liquid volume in the foam is essential in the characterization of foam fluids used for drilling or fracturing. It was observed from a number of studies that bubble size and texture play very important roles in foam fluid rheology. 17 Representative micrographs of 72% and 86% foam qualities are shown in Figures 2 and 3, respectively, at variable elapsed times. Variations in the bubble size with elapsed time are depicted in Figure 4 for different foam qualities (72−86%). From the figures, it can be concluded that better quality of foam provides a more uniform bubble structure and a better continuum. The rate of increase in bubble size is higher when the liquid makes up more of the volume, that is, for lowerquality foams. For higher foam quality (86%), the closely spaced bubbles are more resistant to expanding and bursting and are thus more stable compared than the foam of 72% quality. It is evident from the microscopic structures of foams with different qualities that, initially, the continuum has small regular-shaped structure. With the passage of time, the liquid drains out, and the bubble size increases. With the passage of time, this drained liquid leaves the foam continuum susceptible 19185

dx.doi.org/10.1021/ie502598s | Ind. Eng. Chem. Res. 2014, 53, 19184−19191


Article

Figure 3. Microscopic view of foam (86% quality) structure with elapsed time at (a) 5 and (b) 30 min for 0.45 wt % SDS + 0.5 ppm guar.

Figure 2. Microscopic view of foam (72% quality) structure with elapsed time at (a) 5 and (b) 30 min for 0.25 wt % SDS + 0.5 ppm guar.

to collapse. This susceptibility of the foam is understood in terms of the half-life time of the foam.10 Tables 1−3 provide the data on foam quality with surfactants and guar gum concentration. According to the experimental data, foam quality is a strong function of surfactant concentration and is weakly affected by the polymer concentration. At a constant guar (polymer) concentration, foam quality was enhanced with increasing surfactant concentration irrespective of its ionic state. However, foam quality remained almost unaffected up to a certain limit of guar concentration (here, 1.25 ppm), beyond which degradation of foam quality was observed. On the contrary, foam stability increased substantially upon the addition of guar gum. According to many researchers, guar gum provides stability to the foam and influences the viscosity of the system.18,19 However, adsorption of polymer on the liquid−gas interface generally enhances the interfacial elasticity of the bubble film, preventing film rupture and bubble coalescence, thus providing higher stability to bubbles.20 The same phenomenon is also responsible for preventing the formation of new bubbles and lowering the foam quality at increased guar concentration.

Figure 4. Variation in bubble size with time.

The stability, or half-life time, of foam is a strong function of the concentrations of surfactant and polymer and the ionic state of the surfactant. Foam stability was found to be increased at higher guar−surfactant concentrations. The half-life time varied from 74.2 to 87.77 min as the foam quality increased from 72% to 86% for different surfactant (SDS) concentrations, as shown in Table 2, whereas the maximum half-life time of 153.69 min was achieved at 1.75 ppm guar gum and 0.45 wt % SDS with a 19186



Article

Table 1. Foam Fluid Rheology and Power-Law Parameters for CTAB and Guar Gum guar gum concentration (ppm)

CTAB concentration (wt %)

foam quality (%)

behavior index (n)

consistency index (k) (lbf sn/ft2)

apparent viscosity (μa)

half-life time (min)

0.50

0.25 0.30 0.35 0.40 0.45 0.30 0.35 0.40 0.45 0.30 0.35 0.40 0.45

67 74 84 85 82 69 80 78 71 59 69 70 61

0.340 0.663 0.674 0.707 0.768 0.275 0.546 0.547 0.645 0.259 0.469 0.528 0.558

7.697 0.771 0.703 0.597 0.449 10.229 1.664 1.714 0.988 11.166 2.788 1.931 1.693

40.50 38.00 37.50 40.00 46.00 34.50 36.50 38.00 43.00 33.50 36.00 37.50 40.50

66.31 70.61 74.96 81.99 89.13 90.95 97.77 105.59 103.32 119.84 128.83 139.13 143.27

1.25

1.75

Table 2. Foam Fluid Rheology and Power-Law Parameters for SDS and Guar Gum guar gum concentration (ppm)

SDS concentration (wt %)

foam quality (%)

behavior index (n)


apparent viscosity (μa) (cP)


0.50

0.25 0.30 0.35 0.40 0.45 0.25 0.30 0.35 0.40 0.45 0.25 0.30 0.35 0.40 0.45

70 77 86 84 83 63 72 74 80 77 60 65 74 71 65

0.436 0.407 0.442 0.489 0.511 0.506 0.489 0.481 0.503 0.521 0.378 0.427 0.421 0.440 0.417

3.59 4.328 3.571 2.634 2.371 2.279 2.627 2.812 2.536 2.781 7.312 4.071 4.32 3.835 7.419

34.5 35.0 36.0 36.5 38.5 35.0 35.5 36.5 38.5 39.0 35.0 37.5 38.0 38.5 39.5

74.2 78.19 80.57 85.03 87.77 94.25 97.10 104.76 111.23 114.54 126.34 135.0 143.21 151.07 153.69

1.25

1.75

Table 3. Foam Fluid Rheology and Power-Law Parameters for Brij S20 and Guar Gum guar gum concentration (ppm)

Brij S20 concentration (wt %)

foam quality (%)

behavior index (n)


apparent viscosity, μa (cP)


0.50

0.25 0.30 0.35 0.40 0.45 0.25 0.30 0.35 0.40 0.45 0.25 0.30 0.35 0.40 0.45

72 75 78 81 84 69 72 74 77 81 62 67 70 72 76

0.514 0.519 0.678 0.641 0.756 0.537 0.559 0.681 0.635 0.658 0.542 0.623 0.595 0.585 0.618

2.720 2.514 0.779 0.979 0.431 2.318 1.861 0.731 0.957 0.795 2.073 1.099 1.228 1.225 0.974

45.50 43.50 40.00 39.00 38.00 45.00 42.00 38.50 36.50 35.50 45.50 38.50 35.50 33.00 33.00

62.14 65.31 70.03 72.98 74.65 78.19 81.26 87.29 95.61 98.16 89.77 95.31 102.56 106.49 111.84

1.25

1.75

foam quality of 75%. High-quality foams have more regular and finer structures for longer periods as compared to lower-quality foams.21,22 In high-quality foam systems, the liquid volume in the system is lower; hence, with the passage of time, the volume vacated by draining liquid is lower than that available in lower-quality systems. The expansion of foam bubbles is restricted by the

availability of space, which is lower in the case of higher-quality foams. Foams with the anionic surfactant, SDS, contributed maximum stability to the foam compared to the cationic surfactant CTAB and the neutral Brij S20 because of better interactions of the head groups of the anionic surfactants with the nonionic guar gum.23 19187



Article

3.2. Apparent Viscosity Variation with Surfactant and Guar Gum Concentrations. The effect of cationic surfactant concentration on the apparent viscosity at different guar concentrations is shown in Figure 5. A decreasing trend in

The variation in apparent viscosity with varying SDS and polymer (guar gum) concentrations can be observed in Figure 6. At low SDS concentrations, surfactant and polymer

Figure 6. Variations in apparent viscosity with respect to SDS concentration at given concentrations of guar gum. Figure 5. Effect of cationic surfactant concentration on apparent viscosity of foam fluid at different guar gum concentrations.

molecules were dispersed in the system. As the concentration of SDS was increased, more clusters of smaller sizes formed.31,32 At low ionic strength, the spacing between micelles can be attributed to mutual Columbic repulsion and their need to stick to the polymer chain. A further increase in surfactant concentration saturated the polymer chains. This behavior was observed below the critical micelle concentration (cmc) of the surfactant. At this point, the solution contained SDS micelles that interacted as bound clusters. The interfacial tension between the films of the foam bubbles was then reduced. A number of investigators have observed that it becomes difficult to agitate surfactant−polymer systems at higher viscosities and also that the water transport through the films is impaired, which hinders bubble coalescence.33−35 All of these factors contribute to the reduction in viscosity as the polymer concentration exceeds a certain limiting value.36 The variation in apparent viscosity with varying concentrations of neutral surfactant Brij S20 and polymer can be observed in Figure 7. A neutral surfactant is incapable of

apparent viscosity with increasing cationic surfactant concentration can be observed in the initial stages up to a surfactant concentration of 0.35 wt %, beyond which the trend is completely reversed. The apparent viscosity followed an inverted trend and started increasing with increasing surfactant concentration. In a conventional way, the increase in polymer concentration was accompanied by a viscosity increment due to the interlocking of polymer chains, which formed long structures. Hoff et al.24 and Janiaud et al.25 observed that the magnitude of the foam viscosity is primarily due to interfacial tension between the bubble films within the foam. At lower concentrations, the polymer enhances the viscosity of the foambased drilling fluid by contributing to the viscosity of the base fluid. The viscosity of nonionic polymer was found to be enhanced more by the addition of an anionic surfactant than by the addition of a cationic surfactant. It was found to be least influenced by the addition of nonionic surfactant Brij S20.23−27 The enhanced viscosity is attributed to the adsorption of surfactant molecules on the polymer chain and to the conformational changes in the molecular chains induced by electrostatic forces. Sometimes, when a surfactant is introduced into a system, an initial decrease in the viscosity of the system is observed before it starts to increase. The decrease is attributed to the shrinking of polymer chains due to electrostatic forces between the hydrophobic and hydrophilic tails of the surfactant molecules.28 This was observed in the initial stages for the guar gum and cationic surfactant (CTAB) combination. The interaction between a cationic surfactant and a nonionic polymer is less dominant than that for an anionic surfactant.26−29 The suppressed interaction is due to the larger head groups present on the cationic and neutral surfactant chains, which inhibit their penetration inside the micelle structure of the surfactant. This reduces the formation of surfactant−polymer clusters. Therefore, a reduced interaction is observed as compared to that for the anionic surfactant in the initial stages. The increase in surfactant concentration after that allows the polymer−surfactant interaction and the viscosity of the system to start increasing. Furthermore, the overlap of the hydration cells of the polymer and surfactant head groups plays a vital role in altering the properties of the surfactant−polymer system.26,30

Figure 7. Effect of Brij S20 concentration on the apparent viscosity of foam at different guar gum concentrations.

interacting electrostatically with a nonionic polymer.37,38 Hence, the increment in viscosity in this system was solely because of the increasing surfactant concentration. The increase in surfactant concentration resulted in a better quality of foam. Thus, the polymer only enhanced the stability of the foam bubbles but reduced the interaction between the bubbles. Hence, a continuous reduction in viscosity was observed.39,40 The power-law model (eq 1) was experimentally verified by studying the experimental data. The ranges of consistency and 19188



Article

behavior indexes for different surfactant and polymer combinations are listed in Tables 1−3. The behavior and consistency indexes were calculated using the formulae7 n = 3.32 log

K=

θ600 (1022)n

θ600 θ300

(2)

(3)

where n is the behavior index, K is the consistency index (lb/ 100 ft2), θ600 is the dial reading of the Fann VG viscometer at 600 rpm, and θ300 is the dial reading of the Fann VG viscometer at 300 rpm. These variations lie in ranges in which the developed foam qualities follow the power-law model for the study of rheological behavior as reported by Guo.41 Moreover, the rheological behavior for foam qualities below 60% was neglected as, below this quality, phase separation takes place and an abrupt change in behavior is observed.42 3.3. Gel Strength Variation of Cationic, Anionic, and Neutral Surfactants in a Given Polymer Concentration. Gel strength is the property of a drilling fluid that helps it to suspend the drill cuttings in the fluid at rest. Gel strength is a function of interparticle forces, basically interfacial tension and viscosity (i.e., intermolecular forces).43,44 In general, the higher the interfacial tension and viscosity, the higher the gel strength. Values of gel strength at 10 s, 10 min, and 30 min provide an indication of the gelling capability and capacity of a drilling fluid to suspend cuttings and/or it sticking characteristics. According to Machado and Aragao (1990), the greater a foam’s gel strength, the longer the time it can suspend solids under static conditions. However, excess values can cause pipe-sticking problems. Hence, optimization of the gel strength is essential for the design of a drilling fluid.45 The effects of the concentrations of three different surfactants on gel strength at variable guar concentrations are shown in Figures 8−13. It can be observed from the figures that

Figure 9. Variation in 30-min gel strength with CTAB concentration for given guar gum concentrations.

Figure 10. Gel strength (10-min) vs SDS concentration at given guar gum concentrations.

Figure 11. Effect of SDS concentration on 30-min gel strength at given guar gum concentrations.

Brij S20, a continuous increase in gel strength was observed, as shown in Figures 12 and 13. The anionic and cationic surfactants showed maximum gel strengths at 0.3 wt % surfactant concentrations. This was true for the entire range of guar gum concentrations under study. The trend was also independent of circulation cessation time. This might be due to the change in micelle concentration and orientation in solution. According to various investigators, the starting point of inflection corresponds to the critical micelle concentration, and the ending point signifies the polymer saturation point of the system. The end of this peak is the point at which the polymer saturation point of the system is achieved. After this point, the system becomes independent of polymer addition to the solution.24,46−48 In contrast, in the case of

Figure 8. Gel strength (10-min) vs CTAB concentration for given guar gum concentrations.

the cationic (CTAB) and anionic (SDS) surfactants behaved similarly whereas the gel strength varied differently in the presence of the neutral surfactant (Brij S20). Initially, the gel strength increased up to a certain surfactant concentration for CTAB and SDS, beyond which a continuous decrease was observed followed by stabilization. However, in the presence of 19189



■

Article

AUTHOR INFORMATION

Corresponding Author

*E-mail: [email protected]. Notes

The authors declare no competing financial interest.

■

ACKNOWLEDGMENTS We gratefully acknowledge DST (SB/FTP/ETA-05/2013) and NPIU for their financial support of this project. Thanks are also extended to each person associated with the experimental works.

■

Figure 12. Variations in 10-min gel strength with Brij S20 concentration at given guar gum concentrations.

REFERENCES

(1) Bennion, D. B.; Thomas, F. B.; Jamaluddin, A. M. M. Using Underbalanced Drilling to Reduce Invasive Formation Damage and Improve Well Bore ProductivityAn Update. J. Can. Pet. Technol. 2000, 39 (7), 52−60. (2) Machado, C.; Ikoku, C. U. Experimental Determination of Solids Fraction and Minimum Volumetric Requirements in Air and Gas Drilling. J. Pet. Technol. 1982, 34 (11), 2,645−2,655. (3) Bennion, D. B.; Thomas, F. B. Underbalanced Drilling: A Reservoir Design Perspective. Presented at the Petroleum Society/SPE Conference on Horizontal Well Technology, Calgary, Alberta, Canada, Nov 3, 1999. (4) Guang, C.; Chen, X.; Cheng, X.; Liu, D.; Liu, C.; Wang, D. The Application of Air and Air/Foam Drilling Technology in Tabnak Gas Field, Southern Iran. Presented at the IADC/SPE Asia Pacific Drilling Technology Conference and Exhibition, Bangkok, Thailand, Nov 13−15, 2006; Paper SPE 101560. (5) Bonilla, L. F.; Shah, S. N. Experimental Investigation on the Rheology of Foams. Presented at the SPE/CERI Gas Technology Symposium, Calgary, Alberta, Canada, Apr 3−5, 2000’ Paper SPE 59752. (6) Wan, L. P.; Meng, Y.; Li, Y.; Wang, J.; Shu, X.; Zeng, Q. The Study of the Circulation of Drilling Foam. Presented at the International Oil and Gas Conference and Exhibition in China, Beijing, China, Jun 8−10, 2010; Paper SPE 131068. (7) Darley, H. C. H.; Gray, G. R. Composition and Properties of Drilling and Completion Fluids, 6th ed.; Gulf Professional Publishing: Houston, TX, 2011. (8) Edrisi, A. R.; Gajbhiye, R. N.; Kam, S. I. Experimental Study of Polymer-Free and Polymer-Added Foams for Underbalanced Drilling: Are Two Foam-Flow Regimes Still There? Presented at the SPE Canadian Unconventional Resources Conference, Calgary, Alberta, Canada, Oct 30−Nov 1, 2012; Paper SPE 162712. (9) Negrao, A. F.; Lage, A. C. V. M; Petrobras, S. A.; Cunha, J. C. An Overview of Air/Gas/Foam Drilling In Brazil. SPE Drill. Completion 1999, No. 14, 109−114. (10) Holmberg, K.; Jönsson, B.; Kronberg, B.; Lindman, B. Surfactant and Polymers in Aqueous Solution; John Wiley and Sons: Chichester, U.K., 2003. (11) Livescu, S. Mathematical modelling of thixotropic drilling mud and crude oil flow in wells and pipelinesA review. J. Pet. Sci. Eng. 2012, 98−99, 174−184. (12) Rong-Chao, C.; Rui-He, W. A Three-Segment Hydraulic Model for Annular Cuttings Transport with Foam in Horizontal Drilling. J. Hydrodyn. 2008, 20 (1), 67−73. (13) Salehi, S.; Hareland, G.; Nygaard, R. Numerical simulations of wellbore stability in under-balanced-drilling wells. J. Pet. Sci. Eng. 2010, 72, 229−235. (14) Ozbayoglu, E.; Kuru, E.; Miska, S.; Takach, N. A Comparative Study of Hydraulic Models for Foam Drilling. Presented at the SPE/ CIM International Conference on Horizontal Well Technology, Calgary, Alberta, Canada, Nov 6−8, 2000; Paper SPE 65489. (15) Rand, P. B.; Kraynik, A. M. Drainage of Aqueous Foams: Generation-Pressure and Cell-Size Effects. SPE J. 1983, 23, 152−154.

Figure 13. Variations in 30-min gel strength with Brij S20 concentration at given guar gum concentrations.

natural surfactants, electrostatic forces do not play an important role in altering the gel strength of the system. Neutral surfactants do not have any ions to attract or repel the conformational groups present in the guar polymer. Thus, a comparatively lower increase in gel strength occurs with increasing surfactant concentration, because of the change in foam quality at higher surfactant concentrations. For the prepared foams, all of the guar gum provided gelling strength to the systems, irrespective of the ionic state of the surfactant; thus, an increase in gel strength was observed upon the addition of guar gum for each of the systems.49,50

4. CONCLUSIONS The microscopic characteristics, stability, quality, and rheology of foams prepared with cationic, anionic, and nonionic surfactants and guar gum were investigated in the present study. Variations in the rheology and gel characteristics were studied using surfactants with different ionic behaviors. It can be concluded from the investigation that the anionic surfactant produced the most stable foam with consistent rheology. The addition of the polymer guar gum enhanced the stability of the foams, which can be attributed to the consistent rheology as compared to that of the aqueous foams. The rheological behavior and stability of the foams were also observed to be strong functions of chemical concentration and foam quality. The present investigation involved an in-depth investigation of these variable for the optimization of suitable foam quality. Thus, the present study will be helpful in designing foams suitable for use under dynamic borehole conditions. 19190



Article

(16) Tyrode, E.; Pizzino, A.; Rojas, O. J. Foamabilty and Foam Stability at High Pressures and Temperatures. Rev. Sci. Instrum. 2003, 74, 2925−2935. (17) Sun, X.; Liang, X.; Wang, S.; Yi, L. Experimental study on the rheology of CO2 viscoelastic surfactant foam fracturing fluid. J. Pet. Sci. Eng. 2014, 119, 104−111. (18) Wang, M.; Du, H.; Guo, A.; Hao, R.; Hou, Z. Microstructure control in ceramic foams via mixed cationic/anionic surfactant. Mater. Lett. 2012, 88, 97−100. (19) Wu, M. S.; Sullivan, M. E.; Yee, D. J. The Viscosity of a Foam: Air in Water Emulsion. Colloids Surf. 1984, 12, 375−380. (20) Bera, A.; Ojha, K.; Mandal, A. Synergistic Effect of Mixed Surfactant on Foam Behavior and Surface Tension. J. Surfactants Deterg. 2013, 16, 621−630. (21) Gumati, A.; Takahshi, H. Experimental Study and Modeling of Pressure Loss for Foam-Cuttings Mixture Flow in Horizontal Pipe. J. Hydrodyn. 2011, 23 (4), 431−438. (22) Gajbhiye, R. N.; Kam, S. I. The effect of inclination angles on foam rheology in pipes. J. Pet. Sci. Eng. 2012, 86, 246−256. (23) Mylonas, Y.; Karayanni, K.; Staikos, G.; Koussathana, M. Investigation of Neutral Polymer−Ionic Surfactant Interactions by Fluorescence in Conjunction with Viscosity Measurements. Langmuir 1988, 14, 6320−6322. (24) Hoff, E.; Nyström, B.; Lindman, B. Polymer−Surfactant Interactions in Dilute Mixtures of a Nonionic Cellulose Derivative and an Anionic Surfactant. Langmuir 2001, 17, 28−34. (25) Janiaud, E.; Weaire, D.; Hutzler, S. A Simple Continuum Model for the Dynamics of Quasi-Two Dimensional Foam. Colloids Surf. A 2007, 309, 125−131. (26) Anthony, O.; Zana, R. Effect of Temperature on the Interactions between Neutral Polymers and a Cationic and a Non-Ionic Surfactant in Aqueous Solutions. Langmuir 1994, 10, 4048−4052. (27) Winnik, F. M.; Winnik, M. A. The Interaction of Sodium Dodecylsulfate with (Hydroxypropyl) Cellulose. Polym. J. 1990, 22 (6), 482−488. (28) Shashkina, J.; Philippova, O. E.; Zaroslov, Y. D. Rheology of Viscoelastic Solutions of Cationic Surfactant Effect of Added Associating Polymer. Langmuir 2005, 21, 1524−1530. (29) Wang, G.; Olofsson, G. Ethyl (hydroxyethy1) cellulose and Ionic Surfactants in Dilute Solution. Calorimetric and Viscosity Study of the Interaction with SDS and Some Cationic Surfactants. J. Phys. Chem. 1995, 99, 5588−5596. (30) Mohsenipour, A. A.; Pal, R. Drag reduction in turbulent pipeline flow of mixed nonionic polymer and cationic surfactant systems. Can. J. Chem. Eng. 2013, 91 (1), 190−201. (31) Murai, N.; Makino, S.; Sugai, S. Interaction of Surfactants with Non ionizable Water-Soluble Polypeptides. J. Colloid Interface Sci. 1972, 41 (3), 399−406. (32) Jain, N.; Trabelsi, S.; Guillot, S.; McLoughlin, D. Critical Aggregation Concentration in Mixed Solutions of Anionic Polyelectrolytes and Cationic Surfactants. Langmuir 2004, 20, 8496−8503. (33) Hirasaki, G. J.; Lawson, J. B. Mechanisms of Foam Flow in Porous Media: Apparent Viscosity in Smooth Capillaries. SPE J. 1985, 25, 176−190. (34) Hohler, R.; Addad, S. C. Rheology of Liquid Foam. J. Phys.: Condensed Matter 2005, 17, 1041−1069. (35) Yoshikiyo, M.; Akisadaa, H.; Saito, M.; Matuura, R. Interaction between Ionic Surfactants and Polyethylene Oxide in Relation to Mixed Micelle Formation in Aqueous Solution. J. Colloid Interface Sci. 1996, 61 (2), 233−238. (36) Cho, Y. S.; Laskowski, J. S. Bubble coalescence and its effect on dynamic foam stability. Can. J. Chem. Eng. 2002, 80 (2), 299−305. (37) Fijan, R.; Šostar-Turk, S.; Lapasin, R. Rheological Study of Interactions between Non-Ionic Surfactants and Polysaccharide Thickeners Used in Textile Printing. Carbohydr. Polym. 2007, 68, 708−717. (38) John, P.; Gnanaprakash, G.; Jayakumar, T. Three Distinct Scenarios under Polymer, Surfactant, and Colloidal Interaction. Macromolecules 2003, 36, 9230−9236.

(39) Saintpere. S.; Herzhaft, B.; Toure, A.; Jollet, S. Rheological Properties of Aqueous Foams for Underbalanced Drilling. Presented at the SPE Annual Technical Conference and Exhibition, Houston, TX, Oct 3−6, 1999; Paper SPE 56633. (40) Wejrzanowski, T.; Skibinski, J.; Szumbarski, J.; Kurzydlowski, K. J. Structure of foams modeled by Laguerre−Voronoi tessellations. Comput. Mater. Sci. 2013, 67, 216−221. (41) Guo, B.; Ghalambor, A. Gas Volume Requirements for Underbalanced Drilling: Deviated Holes; Pennwell Corporation: Tulsa, OK, 2002. (42) Lyons, W. C. Air and Gas Drilling Manual; Gulf Professional Publishing, 3rd ed.; Elsevier: New York, 2008. (43) Vijayan, S.; Woods, D. R.; Vaya, H. Bulk and interfacial physical properties of aqueous solutions of sodium lauryl sulphate and lauryl alcohol with air and benzene system: Part I: Aqueous solutions of sodium lauryl sulphate. Can. J. Chem. Eng. 1978, 55 (6), 718−731. (44) Shrestha, L. K.; Aramaki, K. Non-Aqueous Foams: Formation and Stability; John Wiley & Sons, Ltd.: Chichester, U.K., 2012. (45) Machado, J. C. V.; Aragao, A. F. L. Gel Strength as Related to Carrying Capacity of Drilling Fluids. Presented at the SPE Latin America Petroleum Engineering Conference, Rio de Janeiro, Brazil, Oct 14−19, 1990. (46) Witte, F. M.; Engberts, J. B. F. N. Micellar Rate Effects and Factors Determining the Complexation Process. Colloids Surf. 1989, 36, 417−426. (47) Mukherjee, I.; Sarkar, D.; Moulik, S. P. Interaction of Gums (Guar, Carboxymethylhydroxypropyl Guar, Diutan, and Xanthan) with Surfactants (DTAB, CTAB, And Tx-100) in Aqueous Medium. Langmuir 2010, 2623, 17906−17912. (48) Hansson, P.; Lindman, B. Surfactant−polymer interactions. Colloid Interface Science 1996, 1, 604−613. (49) Meszaros, R.; Varga, I.; Gilányi, T. Effect of Polymer Molecular Weight on the Polymer/Surfactant Interaction. J. Phys. Chem. B 2005, 109, 13538−13544. (50) Saxena, A.; Pathak, A. K.; Ojha, K. Optimization of Characteristic Properties of Foam-Based Drilling Fluids. Braz. J. Pet. Gas 2014, 8, 57−71.

19191


Synergistic Effects of Ionic Characteristics of Surfactants on Aqueous

Recommend Documents