Using Screen Models to Evaluate the Injection Characteristics of

Dec 19, 2017 - Therefore, it is of major importance to examine PPG injection characteristics and thus provide a practical guide to screen and determin...
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Article Cite This: Energy Fuels 2018, 32, 352−359

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Using Screen Models to Evaluate the Injection Characteristics of Particle Gels for Water Control Zhaojie Song,† Baojun Bai,*,‡ and Rajesh Challa‡ †

Research Institute of Enhanced Oil Recovery, China University of PetroleumBeijing, Beijing 102249, China Department of Geosciences and Geological and Petroleum Engineering, Missouri University of Science and Technology, Rolla, Missouri 65409, United States



ABSTRACT: A trend in oilfield water management is to use preformed particle gel (PPG), a kind of superabsorbent polymer, to control water production and enhance oil recovery for mature oilfields. Therefore, it is of major importance to examine PPG injection characteristics and thus provide a practical guide to screen and determine the best PPG for a specific reservoir. In this study, a series of experiments were performed using screen models to study the effect of the particle gel swelling ratio (depending on brine concentration), injection rate, and the open hole size of the screen on the gel injection pressure and injectivity. Experimental results illustrate that the PPGs prepared in high concentration brine present higher gel strength than those prepared in low concentration brine. The gel strength is a more controlling factor than the particle size of the swollen PPG for the particle injectivity. At higher injection rates, the injection pressure does not increase significantly with injection rates, which is very consistent with the real-time injection pressure and injection rate change observed during practical gel treatments in oilfields. These gel particle injection behaviors are completely different from the behavior of conventional hard particles in that they are elastic and deformable during extrusion.

1. INTRODUCTION Superabsorbent polymer hydrogels (SAP) are special polymeric materials that can absorb large amounts of saline solutions that are as high as 10 to 1000 times their own weight.1−5 Because of their three-dimensional structure, SAPs do not dissolve in the media. The superswelling characteristic of SAPs makes them ideal for use in water-absorbing applications, such as disposable diapers, feminine napkins, agricultural products, and cosmetic and absorbent pads.6,7 The desired features of superabsorbents are high swelling capacity, high swelling rate, and expected strength of the swollen gel. The majority of studies on superabsorbents cover the first and second features mentioned, i.e., high absorbency and swelling rate. 8−10 Gel treatments have been widely used for conformance control in mature oil reservoirs due to their ability to reduce water flow through high permeability streaks/ fractures without damaging productive zones.11−14 Preformed particle gel (PPG), a kind of SAP, has become a newer material during gel treatment because PPG can overcome some distinct drawbacks inherent in in situ gelation systems, such as lack of gelation time control, uncertainty of gelling due to shear degradation, chromatographic fractionation, or change of gelant compositions, and dilution by formation water.15,16 Besides, the size-controlled microgels could also be used for water permeability reduction through adsorption as monolayers.17−19 Because the agent could penetrate deeply into reservoir rocks without mechanical trapping, the microgel treatment acts as an effective in-depth fluid diversion technology, especially for high matrix flow zones, vuys, and fractures in carbonate reservoirs.20 The properties of specific gels are extremely important for selecting a material for a given application. During conventional hard particle treatment, the diameter ratio of a hard © 2017 American Chemical Society

particle and a pore throat should be matched well so as to achieve desired water permeability reduction. If the ratio is larger than 1/3, then the external cake will be formed to only present face plugging; if the ratio ranges from 1/3 to 1/10, then hard particles will partially penetrate into the pore and an internal cake will be formed; only if the ratio is smaller than 1/ 10 will hard particles migrate through the pores and be produced at the outlet. Besides, the particle shape is also an important parameter for the injection behavior. The angular particles may require more critical injection conditions than round particles.21,22 However, due to their deformability and elasticity, the swollen PPGs pass through porous media much easier relative to hard particles. Through sandpacked coreflooding experiments, Bai et al.23 described PPG propagation through porous media as three patterns including pass, broken and pass, and plug, and presented that a swollen PPG particle can pass through a pore throat with a diameter that is smaller than the particle diameter. Besides, the effect of gelant compositions and reservoir conditions was discussed on the swollen gel strength and swelling capacity.24 Seright25,26 quantified gel propagation and dehydration during extrusion through fracture, and provided a guide on gel treatment design. By performing steady-state water flow experiments, the permeability of gel-filled capillary tubes was found as a function of water flow rate and polymer concentration.27,28 Zhang and Bai29 revealed that PPG propagated like a piston along a fracture, and investigated the factors that influence PPG injectivity and plugging efficiency in a fracture model. Imqam et al.30 conducted extensive experiments on the Received: October 30, 2017 Revised: December 11, 2017 Published: December 19, 2017 352

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shown in Figure 2. The top flange has one hole that is connected to an ISCO 500D syringe pump (Teledyne Technologies, Thousand

opening conduits and examined the effect of the conduit inner diameter and the PPG strength on the ratio of the particle size to the opening diameter, injectivity index, and plugging efficiency. The objectives of this paper are to examine the PPG injection characteristics through screens of various sizes that represent different permeability channels or pore throats in reservoir formation, and to provide an insight into selecting PPGs for conformance improvement. Three governing factors were taken into account including the PPG swelling ratio (related to brine concentration), injection rate, and the open hole size of a screen. Besides, the PPG cycle injection behavior was investigated based on the particle change before and after the passing, which was rarely reported in the earlier literature. These features are highly dependent on the environmental swelling conditions. Therefore, it is imperative that the PPG’s properties are precisely determined under conditions as close to the real circumstances as possible. In this study, the PPGs are allowed to swell to their maximum capacity in four concentrations of brine solution and then subjected to pressure in our apparatus with screens of different sizes.

2. EXPERIMENTAL SECTION 2.1. Materials. 2.1.1. Preformed Particle Gel. A commercial superabsorbent polymer (SAP), provided by Emerging Technologies, was selected as the preformed particle gel for our experiments. Before swelling, the PPG is a dry, white, granular powder. Its size distribution was determined by a sieving test as illustrated in Figure 1. In aqueous

Figure 2. (a) Diagram and (b) physical picture of the screen model. Figure 1. Size distribution of preformed particle gel.

Oaks, CA) through tubing and fitting. The bottom flange has multiple holes that allow the PPG particles to flow through without adding extra pressure. A piston is inserted into the acrylic tube to prevent the direct contact of the injected fluids and PPG particles. Screens with different open hole sizes are placed between the gel particle and the bottom flange. The pressure due to the pumped water pushes the piston, which presses the swollen PPG to enter the glass bead-packed porous media in the lower part of the tube. This model works well under 1000 psi. 2.2. Experimental Scenarios. A total of 12 experiments, shown in Table 1, were conducted to study the effect of the brine concentration used to prepare the swollen gel particles, the injection rate, and the mesh size on the PPG injection pressure. 2.3. Experimental Setup and Procedure. 2.3.1. Experimental setup. To set up the apparatus, the PPG sample of the desired concentration must be ready beforehand. • The PPG is carefully prepared using the desired concentration of brine solution, and the PPG is allowed to swell completely. • The piston is inserted into the top of the transparent acrylic tube; the tube is then packed with the PPG sample of the desired brine concentration.

solutions, the PPG can absorb a large amount of water due to the hydrogen bond with water molecule. The concentration of sodium chloride will have an effect on the water absorbent capacity.31,32 The preparation of the swollen PPG sample used in the experiments was described in the earlier report,1,33 and the median sizes of swollen PPG samples prepared in different brine concentrations (0.05, 0.25, 1, and 10%) were 4.4, 2.2, 1.2, and 0.7 mm, respectively. 2.1.2. Brine. Four concentrations of brine were selected to prepare the swollen PPG, based on the significant differences in their swelling ratio: 0.05%, 0.25%, 1%, and 10% (wt %) NaCl brine. 2.1.3. Screens. Stainless steel wire cloths of three different sizes were chosen: 150-, 80-, and 40-mesh. The open hole sizes of three screens were 106, 180, and 380 μm, respectively. Various screens with different sizes can represent different permeability channels or pore throats in reservoir formation. The ratio of the swollen particle and high permeability channel, i.e., open hole of the screens, ranged from 2 to 42. The wire cloth was cut into small circles so it could be placed in the apparatus as described later. 2.1.4. Screen Model. A screen model is a long acrylic tube to which end plates are attached by two flanges using steel rods and nuts as 353

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Energy & Fuels Table 1. Summary of the Screen Experiments Performed screen

0.05% brine-prepared PPG

0.25% brine-prepared PPG

1% brine-prepared PPG

10% brine-prepared PPG

150-mesh 80-mesh 40-mesh

x x x

x x x

x x x

x x x

• The screen on which the experiment is to be performed is placed above the holes in the bottom cap. • The packed tube is then set on the bottom cap with the rods, and the top cap is put on the top of the transparent acrylic cylinder with the piston at the top. • The apparatus is then tightly secured using washers and nuts. • A pressure gauge is connected at the bottom of the transparent acrylic tube to monitor the pressure changes with respect to the injection rate. 2.3.2. Procedure for Screen Experiments. The apparatus was set up and connected to the Teledyne ISCO 500D syringe pump from the top cap through which distilled water was pumped at a constant flow rate. Before connecting the apparatus to the pump, we ascertained that there was no air gap in the outlet line of the pump connected to the top cap of the apparatus. The outlet line connected to the apparatus must be tightened to prevent any water leak. The experimental procedure is detailed as follows: • Gas between the piston and the top cap must be released and filled with distilled water to avoid a two-phase medium. • Initially, the pump is run at a constant injection rate of 1 mL/ min, and the pump pressure is constantly observed for a pressure drop to indicate the movement of piston. The pressure noted is the minimum required pressure to move the piston. • Noting the minimum pressure to move the piston, the pump is run at a constant injection rate of 0.1 mL/min, and the pressure response is monitored in the gauge connected to the bottom of the acrylic cylinder. • If there is no gel or brine discharge from the apparatus, then the injection rate is increased to 0.2 mL/min. • If there is any discharge after increasing the injection rate, then the discharge flow rate is calculated by measuring the volume of the gel collected in a specific amount of time. • For each particular injection rate, the pressure is monitored, and when a stable pressure is observed, it is noted as the constant pressure at that particular injection rate. • The process is repeated at multiple injection rates, and the constant pressures for each rate are noted. • The procedure is repeated until the pressure difference is negligible even when the increase in the injection rate is significant. The above procedures are repeated for different screens and different brine concentrations of PPG. All experiments were performed at room temperature (22 °C or 72 °F), and the data obtained were plotted as injection pressure versus injection rate. Temperature mainly affects the gel swelling ratio. The gel strength is the same when the swelling ratio is the same no matter what the temperature is. We evaluate the particle performance through screen models at wide range of swelling ratio, which can reflect temperature effect.

Figure 3. Swelling ratio of the PPG as a function of time and brine concentration.

be reached within 1 h for each sample. The final PPG swelling ratio depends on the brine concentration. The higher the brine concentration, the smaller the final swelling ratio, as presented in Figure 4. This phenomenon is attributed to the charge

Figure 4. Effect of brine concentration on the final swelling ratio of the PPG.

shielding effect.34,35 As brine concentration increases, the electrostatic repulsion between anionic moieties in polymeric chains and their attraction to metallic cations in brine decrease. It results in declined osmotic pressure and thus lower gel absorbency to brine. For high brine concentrations, the PPG swelling ratio exhibits slight change with the rising of brine concentration. It is because the anionic moieties in polymeric network are the limiting reagents for the cross-linking process. The relationship of the swelling ratio to the brine concentration can be well fitted using a power-law equation with a correlation factor of 0.9617:

3. RESULTS AND DISCUSSION 3.1. Effect of Brine Concentration on Swelling Capacity. The swelling ratio, defined as the ratio between the PPG particle volume after and before swelling, is evaluated as a function of the brine concentration. Figure 3 presents the PPG swelling ratio change with time at different brine concentrations. The PPG particles swell very quickly due to the osmotic pressure between PPG internal network and the external brine solutions, and the maximum swelling ratio can

R = 65.535 × C −0.296

(1)

where R is the swelling ratio, and C is the brine concentration by percent. 354

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Energy & Fuels 3.2. Effect of Various Parameters on the PPG Injection Pressure. 3.2.1. Brine Concentration Effect. Figure 5 depicts the effect of the brine concentration of the PPG on

Figure 6. Injection pressure as a function of the injection rate and screen size for 0.05% brine-prepared PPG. Figure 5. Injection pressure as a function of injection rate and PPG brine concentration for 150-mesh screen.

particular injection rate, the injection pressure decreases with the increasing open hole size of the screen (i.e., lower mesh number). Additionally, the swollen PPG samples prepared in 0.25%, 1%, and 10% brine exhibit the similar results. 3.2.4. Repacking Effect. The purpose of these sets of experiments was to determine if the swollen PPG passed through the screen by elongating and deforming temporarily or by particle size change, which would be indicated by the change in injection pressure with respect to the injection rate during the passing of the PPG through the screen. The procedures followed in these experiments were similar to those of the earlier experiments. The effluent PPG from the initial passing experiment was repacked into the apparatus with the same screen, and the experiment was repeated with the same procedures. The repacking experiments were performed on the two PPG samples prepared in 0.05% and 1% brine separately for 150- and 40-mesh screens. Figure 7 presents the effect of repacking on the injection pressure in 150- and 40-mesh screens for the swollen PPG prepared in 0.05% brine. It should be noted that some free water comes out of the swollen PPG during initial passing, which means the PPG for repack-1 and repack-2 concentrates. So the injection pressure for repack-1 and repack-2 is supposed to increase. But from Figure 7a, it can be clearly observed that the injection pressure for repack-1 and repack-2 is much smaller than the original injection pressure at the same injection rate, suggesting that the PPG particles may have deformed and changed in shape permanently during the initial passing. At lower injection rates, the injection pressure is almost the same for repack-1 and repack-2. But at higher injection rates, the injection pressure is lower for repack-2 than for repack-1. Figure 7b shows that the injection pressure during the initial passing is more than three times the injection pressure for repack-1, and the injection pressures for repack-1 and repack-2 are almost the same. Figure 8 depicts the particle size for the 0.05% brine-prepared PPG sample in each mesh for initial passing and repack-1. Compared to the original particle size of the 0.05% brine-prepared PPG, the particles appeared to be elongated and permanently deformed in shape during the initial passing through the 150-mesh screen. However, unlike the particles passed through 150-mesh screen, the particles appeared to be cut in shape in order to pass through the 40mesh screen. As the mesh size increased, the PPG particles were cut during passing through the mesh, but at the finer

the PPG injection pressure for the 150-mesh screen. The figure uniquely demonstrates that at the same injection rate, the injection pressure increases with brine concentration. And the experiments with 80- and 40-mesh screens present the similar results. Before the experiments were conducted, it was hypothesized that the injection pressure for the sample prepared with low salinity brine would be higher than that prepared with high salinity brine because the swollen particle size is larger at the lower brine concentration. However, the experimental results show a completely different trend, which indicates the softness or deformability of the swollen particles is more dominant in influencing PPG injection pressure than the particle size of the swollen PPG. The swollen particles in low salinity brine are softer or more deformable than those in high salinity brine; thus, the low salinity brine-prepared PPG presents a lower injection pressure. 3.2.2. Injection Rate Effect. Figure 5 also indicates that the injection pressure increases with the injection rate for all the brine concentrations of the PPG. However, the relationship is not linear. At higher injection rates, the injection pressure increases slightly with the injection rate. For example, for the PPG swollen with 10% NaCl brine in 150-mesh screen, the pressure only increases 10 psi (from 250 to 260 psi) as the injection rate doubles from 1.16 to 2.2 mL/min. This trend is consistent with the findings of the practical PPG injection in oilfields, for which injection pressure does not significantly increase as the injection pumping rate rises.36,37 3.2.3. Mesh Size Effect. Three screens were chosen based on the difference in their open hole size, of which the 150mesh screen has the smallest opening size, and the 40-mesh screen has the largest opening size. The open hole size of each screen might represent a different pore size or fracture width in the channeled formation. The experiments were conducted on four PPG samples prepared with different brine concentrations. Figure 6 illustrates the effect of mesh size on PPG injection pressure for the swollen PPG sample prepared in 0.05% brine. It can be seen that the injection pressure increases with screen mesh size (i.e., higher mesh number). For example, for the PPG sample prepared in 0.05% brine, at the same injection rate of 0.1 mL/min, the PPG injection pressures for 150-, 80-, and 40-mesh screens are 32, 22, and 9 psi, respectively. This clearly demonstrates that at any given 355

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Energy & Fuels

through the smaller open hole. And the trend of the elasticity index n almost indicates the PPG prepared in the higher salinity brine presents the less deformability. 3.3. Effect of Various Parameters on the PPG Injectivity. 3.3.1. Brine Concentration Effect. PPG injectivity refers to the ratio of the PPG injection rate to the injection pressure and represents the difficulty of injecting PPG. A higher PPG injectivity indicates an easier injection. Figure 10 demonstrates the effect of brine concentration on PPG injectivity for the 150-mesh screen. The figure shows that the PPG injectivity decreases with the increasing brine concentration of the PPG at the same injection rate. And the experiments with 80- and 40-mesh screens present similar results. The results are in line with the effect of brine concentration on PPG injection pressure, and also indicate the gel strength, softness, or deformability of swollen particles is more dominant to PPG injection. The swollen PPG particles prepared in low salinity brine are softer or more deformable, which is consistent with the trend of the gel elasticity index in eq 2. 3.3.2. Injection Rate Effect. Figure 10 also depicts the effect of injection rate on PPG injectivity. For each brine concentration of swollen PPG sample, the injectivity increases as the PPG injection rate increases, indicating that PPG is a pseudoplastic material and exhibits shear-thinning characteristics. 3.3.3. Mesh Size Effect. Figure 11 illustrates the effect of the mesh size on PPG injectivity for the 0.05% brine-prepared swollen PPG sample. It can be seen that the injectivity increases with increasing open hole size (i.e., lower mesh number). This means that a larger open hole size presents a lower flow resistance to the PPG. Additionally, the swollen PPG samples prepared in 0.25%, 1%, and 10% brine exhibit the similar results.

Figure 7. Injection pressure as a function of the injection rate for 0.05% brine-prepared PPG, using (a) 150-mesh screen and (b) 40mesh screen for the initial passing experiment and two repacking experiments.

4. CONCLUSIONS Our work examines the effect of the gel strength and particle size of the swollen PPG on the injection pressure through screens with various open hole sizes. The results characterize the effect of brine concentration on the PPG swelling behavior and also on the PPG injectivity characteristics. (1) PPG swelling ratio depends on brine concentration, and they can be fitted well using a power-law rheology equation. (2) The higher the concentration of the brine used to prepare the PPG, the lower the PPG injectivity becomes. The gel strength is a more controlling factor than the particle size of the swollen PPG for the particle injectivity. (3) At higher injection rates, increasing the injection rate does not significantly raise the injection pressure. The relationship between injection pressure and injection rate can be a good fit for the power-law rheology equation. PPG injectivity increases with an increase in the injection rate, indicating that PPG exhibits shearthinning characteristics. (4) PPG injection pressure declines and the injectivity increases with increasing open hole size (i.e., lower screen mesh number). (5) The PPG particles are elongated and deformed, or permanently cut in shape during passage through the mesh. The PPGs prepared in high concentration brine

mesh size (150-mesh) they were elongated and deformed in shape during passing through the screen. Figure 9 presents the effect of repacking on the injection pressure in 40-mesh screen for the swollen PPG prepared in 1% brine. The injection pressure for repack-2 is lower than that for repack-1 at the same injection rate. This shows that the particle was permanently deformed in both the initial passing and repack-1. This clearly indicates that the PPG prepared in 1% brine has greater gel strength than the PPG prepared in 0.05% brine. This finding was also proven in our previous study.5 The PPG prepared in 1% brine exhibited a higher storage modulus (920 Pa) than the PPG prepared in 0.05% bine (650 Pa), and the storage modulus of the PPG prepared in 10% bine was 1360 Pa. 3.2.5. Rheology Models. When plotting the initial passing experimental results with 150- (Figure 5), 80-, and 40-mesh screens on a log−log plot, the data can be a good fit for the power-law rheology equation: P = β × qn

(2)

where P is the injection pressure, psi; q is the injection rate, mL/min; β is coefficient; and n is the gel elasticity index. Table 2 lists the coefficients and correlation factors of the fitting equations. Usually, non-Newtonian fluid exhibits the power-law rheology characteristic when flowing through a rigid porous medium. The trend of the coefficient β represents the PPG prepared in the higher salinity brine is harder to flow 356

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Figure 8. 0.05% Brine-prepared PPG sample (a) at the initial condition, (b) after initial passing through 150-mesh screen, (c) after repack-1 through 150-mesh screen, (d) after initial passing through 40-mesh screen, and (e) after repack-1 through 40-mesh screen.



present higher gel strength than those prepared in low concentration brine.

AUTHOR INFORMATION

Corresponding Author

*Tel: +1 573 341 4016. E-mail: [email protected] (B.B.). ORCID

Zhaojie Song: 0000-0003-1390-5653 Baojun Bai: 0000-0002-3551-4787 Notes

The authors declare no competing financial interest.



ACKNOWLEDGMENTS The authors are highly appreciative of the financial support for our work from the Research Partnership to Secure Energy for America (RPSEA), the US Department of Energy (07123-02), and the China Scholarship Council. The support from PetroChina Innovation Foundation (2015D-5006-0209) and

Figure 9. Injection pressure as a function of the injection rate for 1% brine-prepared PPG, using 40-mesh screen for the initial passing experiment and two repacking experiments.

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Energy & Fuels Table 2. Coefficients of Fitting Equations for PPG Injection Pressure As a Function of Injection Rate screen

brine concentration (%)

coefficient β

elasticity index n

R2

150-mesh

10 1 0.25 0.05 10 1 0.25 0.05 10 1 0.25 0.05

244.48 141.87 97.943 65.825 131.84 101.46 52.737 41 81.394 56.874 26.048 16.591

0.0991 0.1123 0.2166 0.2843 0.112 0.139 0.1974 0.2414 0.2054 0.3002 0.2153 0.2642

0.9691 0.9538 0.8907 0.9767 0.9613 0.9888 0.9926 0.9733 0.9683 0.9765 0.9949 0.9965

80-mesh

40-mesh

permeability channeling and vugular communication. Proceedings of the SPE Abu Dhabi International Petroleum Exhibition and Conference; Abu Dhabi, UAE, Nov 3−6, 2008; DOI: 10.2118/117155-MS. (4) Goudarzi, A.; Zhang, H.; Varavei, A.; Taksaudom, P.; Hu, Y.; Delshad, M.; Bai, B.; Sepehrnoori, K. A laboratory and simulation study of preformed particle gels for water conformance control. Fuel 2015, 140, 502−513. (5) Imqam, A.; Bai, B. Optimizing the strength and size of preformed particle gels for better conformance control treatment. Fuel 2015, 148, 178−185. (6) Kudel, V. Encyclopedia of Polymer Science and Engineering, 2nd ed.; Wiley: New York, 1985, Vol. 7, pp 783−806. (7) Sharma, S.; Dua, A.; Malik, A. Polyaspartic acid based superabsorbent polymers. Eur. Polym. J. 2014, 59, 363−376. (8) Kabiri, K.; Zohuriaan-Mehr, M. J. Superabsorbent hydrogel composites. Polym. Adv. Technol. 2003, 14 (6), 438−444. (9) Ishizaki, T. G.; Tani, K. Experimental study of film forming effect of water-soluble polymer for polymer sampling. Proceedings of the ISRM International Symposium6th Asian Rock Mechanics Symposium; New Delhi, India, Oct 23−27, 2010. (10) El-karsani, K. S. M.; Al-Muntasheri, G. A.; Hussein, I. A. Polymer systems for water shutoff and profile modification: A review over the last decade. SPE Journal 2014, 19 (1), 135−149. (11) Zaitoun, A.; Rahbari, R.; Kohler, N. Thin polyacrylamide gels for water control in high-permeability production wells. Proceedings of the SPE Annual Technical Conference and Exhibition; Dallas, TX, Oct 6−9, 1991; DOI: 10.2118/22785-MS. (12) Zitha, P. L. J.; Darwish, M. M. I. Effect of bridging adsorption on the placement of gels for water control. Proceedings of the SPE Asia Pacific Improved Oil Recovery Conference; Kuala Lumpur, Malaysia, Oct 25−26, 1999; DOI: 10.2118/57269-MS. (13) Seright, R. S. Cleanup of oil zones after a gel treatment. SPE Production & Operations 2006, 21 (1), 237−244. (14) Sang, Q.; Li, Y.; Yu, L.; Li, Z.; Dong, M. Enhanced oil recovery by branched-preformed particle gel injection in parallel-sandpack models. Fuel 2014, 136, 295−306. (15) Coste, J. P.; Liu, Y.; Bai, B.; Li, Y.; Shen, P.; Wang, Z.; Zhu, G. In-depth fluid diversion by pre-gelled particles. Laboratory study and pilot testing. Proceedings of the SPE/DOE Improved Oil Recovery Symposium; Tulsa, OK, Apr 3−5, 2000; DOI: 10.2118/59362-MS. (16) Chauveteau, G.; Omari, A.; Tabary, R.; Renard, M.; Veerapen, J.; Rose, J. New size-controlled microgels for oil production. Proceedings of the SPE International Symposium on Oilfield Chemistry; Houston, TX, Feb 13−16, 2001; DOI: 10.2118/64988-MS. (17) Chauveteau, G.; Tabary, R.; Le Bon, C.; Renard, M.; Feng, Y.; Omari, A. In-depth permeability control by adsorption of soft sizecontrolled microgels. Proceedings of the SPE European Formation Damage Conference; The Hague, Netherlands, May 13−14, 2003; DOI: 10.2118/82228-MS. (18) Rousseau, D.; Chauveteau, G.; Renard, M.; Tabary, R.; Zaitoun, A.; Mallo, P.; Braun, O.; Omari, A. Rheology and transport in porous media of new water shutoff/conformance control microgels.

Figure 10. PPG injectivity as a function of the injection rate and PPG brine concentration for 150-mesh screen.

Figure 11. PPG injectivity as a function of the injection rate and screen size for the 0.05% brine-prepared PPG.

Science Foundation of China University of Petroleum, Beijing (2462014YJRC053, 2462015YQ1105) is also much appreciated.



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DOI: 10.1021/acs.energyfuels.7b03338 Energy Fuels 2018, 32, 352−359

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DOI: 10.1021/acs.energyfuels.7b03338 Energy Fuels 2018, 32, 352−359