Polyethylenimine under High

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General Research

Gelation of Emulsified Polyacrylamide / Polyethylenimine at HighTemperature High-Salinity Conditions: Rheological Investigation Abdelhalim I.A. Mohamed, Ibnelwaleed A. Hussein, Abdullah S Sultan, and Ghaithan A Al-Muntasheri Ind. Eng. Chem. Res., Just Accepted Manuscript • DOI: 10.1021/acs.iecr.8b02571 • Publication Date (Web): 15 Aug 2018 Downloaded from http://pubs.acs.org on August 18, 2018

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Industrial & Engineering Chemistry Research

Gelation of Emulsified Polyacrylamide / Polyethylenimine at HighTemperature High-Salinity Conditions: Rheological Investigation Abdelhalim I.A. Mohamed1, Ibnelwaleed A. Hussein2, Abdullah S. Sultan3,4*, Ghaithan A. AlMuntasheri5 1

Petroleum Engineering Department, University of Wyoming, Laramie, WY 82071, USA Gas Processing Center, College of Engineering, Qatar University, PO Box 2713, Doha, Qatar 3 Petroleum Engineering Department, King Fahd University of Petroleum & Minerals; Dhahran 31261, Saudi Arabia 4 Center for Integrative Petroleum Research, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia 5 EXPEC Advanced Research Center, Saudi Aramco, Dhahran 31311, PO Box 62, Saudi Arabia 2

Abstract Emulsified gels are proposed as a method of water shut-off in oil and gas reservoirs and designed to separate into a water phase and an oil phase at reservoir conditions. A first of its kind rheological study on the gelation kinetics and strength of organically crosslinked polyacrylamide (PAM) with polyethyleneimine (PEI) emulsified into a diesel phase is presented. A lower rate of crosslinking is achieved when emulsified PAM/PEI are compared with non-emulsified PAM/PEI systems. For the stable emulsified PAM/PEI formulation (with no separation), the elastic modulus reduced by ~54% at 120 ℃ in comparison with the non-emulsified system. It is suggested that the emulsification acts as insulator hence heat transfer to the gelant is slow. The elastic modulus of the emulsified PAM/PEI increased by about 29% when the temperature is raised from 120 ℃ to 150 ℃. The elastic modulus decreased in the presence of salts leading to low gel strength and longer gelation time. Ammonium chloride proved to be more efficient than NaCl in the retardation of emulsified gels. The gelation kinetics of the emulsified PAM/PEI is analyzed using Avrami based model. The activation energy for emulsified gels was found to be ~ 10 times higher than non-emulsified gels.

Keywords: Water Shut-off; Polymeric Gels; Emulsified Gel; Gelation Kinetics; Rheology. *Corresponding Author: [email protected]

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Industrial & Engineering Chemistry Research 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Introduction Water production is an inevitable consequence of the hydrocarbon recovery operations; nonetheless, it is considerably the major excessive stream allied with hydrocarbon exploration and production.1-3 When produced water from a specific field exceeds economic limits, this fact necessitates developing a technique by which water production is controlled. The production of water was reported to be in the order of 210 million barrels per day (BPD) globally in the year 1999. 4 Bailey et al. 5 reported the same figure for the year 2000. This amount increased to 249 million BPD in the year 2005, 6 and a similar number was recorded in 2007. U.S alone produced an average volume of 57.4 million BPD in 2007,3 for an oil-water ratio of roughly 1:3. Approximately, $40 billion is spent annually on handling the unwanted produced water from oilfields,5 and the number has increased to $45 billion in the year 2002.7 No more recent updates on the amounts and cost of produced water are available, but these figures are anticipated to rise with the depletion of conventional oil wells.8 The disposal of produced water affects the environment seriously, especially if the produced water contains mercury, arsenic and other salts.9 Water is also responsible for most of the corrosion and scale problems in the oilfields.10-12 Consequently, there is a need for a remediated technique that totally shuts off or reduces the water production. Polymer gels are suitable for total blockage of water producing zones.13,14 The use of polymeric gels results in reducing water relativepermeability during conventional oil and gas production15,16 and improving injection well sweep efficiency.17-22 It is worth mentioning that in an unconventional reservoir, specifically tight gas formations, due to their very low porosity (5-15%) and permeability (< 0.1 mD); the use of traditional techniques were found to yield an undesirable outcome, henceforth alternative methods were proposed.22,23 Commonly, inorganic cross-linked gels 24,25 and organically cross-linked gels 26,27 are used in the oilfields. Literature reports revealed that organically cross-linked gels were more thermally stable in comparison with inorganic gels,27,28-30 which makes it more suitable for high-temperature applications. An extensive review of available literature on the chemistry and field application of various polymer gel systems for a temperature setting over a range of 40 to 150 ℃are reported.31,32 Nevertheless, there exists a possibility that polymeric gels may reduce hydrocarbon flow significantly, alongside the water. Additionally, given the shortage of means to optimally set a plugging barrier obstruction, accompanied with the high operational costs, the need arises for 2 ACS Paragon Plus Environment

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developing a selective technique. The optimistic scenario is to decrease water production significantly without notably damaging oil and gas productivity by developing a formulation that can be pumped into a production well without isolating hydrocarbon productive zones. Emulsified gels are proposed as a smart method for shutting off unwanted water produced from the oilfields without risking their productivity.33-36 In this technique, a mixture of polymer solution (gelant) is emulsified into an oleic phase, using a suitable surfactant, and then injected near the wellbore. At reservoir conditions, the emulsified system is formulated to break up into oleic and water phases. In the pore space, the oleic phase remains mobile, while the water phase gels up forming a viscoelastic gel blocking formation water flow. The breaking of the emulsified gel and then the subsequent gelation are critical parameters for successful gelant placement. Consequently, gel with satisfactory strength is needed to block the water pathways effectively. Furthermore, proper separation and longer gelation time are required especially for high-temperature reservoirs to avoid gelation in the tubing during the placement. Usually, retarders (i.e. salts) are used to slow down the gelation process and keep the gelant flowable until it reaches the target zone.31,32 The separation of the emulsified gel and subsequent gelation are a function of the concentration of the different components, salinity of mixing water, temperature and time.35 The accurate determination of gelation time is a vital factor in gelant placement to determine the time at which a 3-D gel’s structure is formed. Consequently, rheological measurements of emulsified polymeric gels are used to determine the gelation time and gel’s strength, which reflects the gel ability to withstand the water flow. No reports are available on the correlation of elastic modulus with the gel lifetime though the gel lifetime depends on many other factors. However, it is speculated that the higher the modulus, the higher the stored energy and resistance to small deformations. Gel strength depends mainly on the elasticity, which can be evaluated by measuring the elastic properties (storage modulus) through dynamic shear testing. The storage modulus for different types of polymer gels utilized for water control were reviewed by our group and reported elsewhere.37 Stavland et al.34 report the only available study on emulsified gels in 2006 where acrylamide and tert-Butyl acrylate (TBA) are cross-linked with PEI. The gelant was loaded in a test tube, and then heated to 90°C for a given time, then the water phase relative viscosity was calculated at ambient temperature (25°C). The rate of gelation was evaluated against a reference cross-linked polymer (non-emulsified). A slightly longer gelation time was observed with the emulsified gels, which is 3 ACS Paragon Plus Environment


suggested to be due to the loss of some of the cross-linker (PEI) into the diesel. Moreover, authors claimed a slight increase in the gel strength when the standard cross-linked polymer was tested versus the emulsified polymers, but no data on the gel strength was presented. More recent research revealed that more cost-effective polyacrylamide (PAM) homopolymer could substitute PAtBA.3739

. The cross-linking between polyacrylamide (PAM) and polyethyleneimine (PEI) was thought to

be through a nucleophilic substitution in which the imine nitrogen in PEI will replace the amide group at the carbonyl carbon of PAM.38 Thus, it is important to examine the potential use of PAM /PEI in preparing emulsified gels to produce thermally stable gels for high-temperature high salinity reservoirs. Dynamic (oscillatory) shear measurements are usually used to study the viscoelastic properties of the gelling systems. The elastic and viscous behaviors are interpreted through the storage and loss modulus33,37. The storage modulus (G') reflects the stored recoverable energy of the material, whereas, the loss modulus (G'') accounts for the mechanical energy dissipated into heat due to viscous forces. The ratio of (G''/G') determines the shift angle (tan δ) between the stress and strain.37 Gelation kinetics can be determined by monitoring the evolution of the storage and loss moduli with time.40,41 More fundamental details of dynamic oscillatory testing can be found elsewhere.40-45. Investigation of the rheology of emulsified polymeric solutions is necessary for estimating the gelation time to avoid gel formation in the piping system during injection. In addition, information about the ultimate gel strength is essential for the final application. In this study, for the first time, gelation kinetics and gel strength of an emulsified gel optimized for high gel strength were measured for the temperature range 120 to 150 ℃which is representative of high-temperature reservoirs. Moreover, the impact of different parameters on the strength of the emulsified PAM/PEI gel is studied at high temperatures. These parameters include polymer concentration, emulsifier type, and emulsified gel formulation (emulsified gel separation time), the salinity of mixing water, retarder type. The different parameters are varied with the objective of developing a formulation that provides the highest gel strength at the lab level. The optimized gel composition (high strength) are recommended for further testing for field application. The main objective of studying the gelation kinetics is evaluating the gel blocking characteristic (gel strength) for effective water shut off, moreover estimate gelation time to ensure gelant flowability in the piping system during the injection process.


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Experimental Studies Materials Two surfactants by AkzoNobel are used, ANSC (CRV) is acetate of hydrogenated tallow amine with HLB of 6.8 (Armac HT Prills), and Ethomeen T/12 is ethoxylated tallow amine (HLB of 10.1), additional physical and chemical properties are given elsewhere.35,46 Field mixing water (FMW) and seawater (“SW”, i.e. a compositional analysis of Persian Gulf sample) were used as the water phase; Table 1 shows their chemical analysis. Diesel from local gas stations, which is representative of that used in the field for preparing emulsified acids was used. Two different polymers solutions were used, (i) Polyethyleneimine (PEI) was used as a cross-linker; PEI has a molecular weight of 70 kg/mol and activity 30 wt.%, with a pH of 11.7 and (ii) Polyacrylamide (PAM) has molecular weight ranges from 250 to 500 kg/mol with a pH of 4.0 was supplied by SNF Floerger as a solution of 20 wt.% concentration. All Salts used in this study were American Chemical Society (ACS) grade. Procedure A systematic routine was used to prepare emulsified and non-emulsified polymer gels to ensure reproducibility. The Polymer gels were formed by adding a fixed quantity of PAM to either FMW or SW while stirring. Afterward, a specific quantity of cross-linker (PEI) was added dropwise; and the mixture was kept under continuous stirring for 10 minutes to obtain a homogenous mixture. This blend is referred to as gelant. The emulsified system was formed with one of the two surfactants. The emulsifier was added at the desired concentration to the oleic phase. Enough time (five minutes) was maintained for the emulsifier to mix in the diesel thoroughly. Then, 70 vol % gelant was gradually added to the 30 vol % emulsifier and diesel solution, while continuous agitation was performed using magnetic mixer, for an extra five minutes until a homogeneous emulsion is obtained (i.e. 40 minutes). The mixing intensity varied depending on what stability was desired, for a stable, no separation formulations 2500 ppm was used, whereas 1000 rpm was employed to prepare formulations with a complete separation in one hour, more details are available elsewhere. 33, 46-47 NaCl and / or NH4Cl were added to FMW and/or SW prior to the addition of the polymers to investigate how the retarders influence the gelation time as well as the gel strength. Generically, two emulsified gel formulations (different separation time) were prepared in SW and/or FMW, to study the impact of separation time on the gel strength and gelation time. Formulation 1 (no 5 ACS Paragon Plus Environment


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separation), the emulsified gel did not break down into its original components (water and oil phases) throughout the test time. Formulation 2 completely separated after an hour as shown in Fig. 1. Before embarking on a discussion of the results the exact specifications of formulations recipe must be emphasized, that is, 3vol% Ethomeen T/12 at 2500 and 1000 rpm used to prepare Formulation 1 (F1- Ethomeen T/12) and Formulation 2 (F2- Ethomeen T/12), respectively. While, 0.35 vol % ANSC (CRV) at 1000 rpm used to prepare Formulation 2 (F2- ANSC (CRV)). Afterward, the formulation was tested in a rheometer equipped with a high-pressure hightemperature cell.

Table 1. Make-up brine chemical analysis Concentration, mg·L-1 Ion Field mixing water

Sea water

Na+

175

17,085

Mg2+

46

2,200

Ca2+

112

1,040

Cl1-

377

31,267

SO42+

266

4,308

TDS*

976

55,900

*Total dissolved solids (TDS) were calculated by summation.


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a

b

c

Diesel

Emulsified Gels Gels

Figure 1. Emulsified Gels generic formulations (a) No separation (Formulation 1), (b) Intermediate separation and (c) Complete separation (Formulation 2)

Apparatus All rheological tests were performed in a high-pressure cell geometry mounted on the rheometer (Discovery Hybrid Rheometer, model DHR-3) manufactured by TA Instruments. The geometry with bob and cup of diameter 26 and 28 millimeters, respectively. All tests were performed at a pressure of 3.45×106 Pa (500 psi), to prevent boiling, and in the temperature range 120o to 150 ℃ (248 to 302oF). The instrument has a torque range

of 100 µN.m to 0.2 N.m, a functioning

temperature range of -10 to 150 oC, (14 to 302oF), and a maximum applied pressure of was 13.8×106 Pa (2,000 psi). In order to perform dynamic oscillatory testing, the strain used should be inside the linear viscoelastic range. The dynamic measurements were carried out at a fixed strain of 10%, and frequency of 1 Hertz (Hz), which was proven to be in the linear viscoelastic range for the PAM/PEI see Figure 2 in.37



Results and Discussions Impact of Emulsification on the Polymeric Gel To investigate the impact of emulsification on gel strength, a polymeric gel was compared to an emulsified gel prepared at ambient temperature and containing PAM/PEI (9/1) wt%. Then, the effect of emulsification was investigated at 120 ℃ (248 ℉). It should be mentioned that the time zero is measured as the time at which the sample reaches the desired set temperature. For instance, it took the sample 16 minutes to reach 120 ℃ (248 ℉) starting from ambient conditions. The results are shown in Fig. 2, and three distinctive regimes are identified. An induction phase in which Gꞌ(t) oscillates up to about 2 Pa. Very low values of storage modulus are obtained throughout this period, which is due to the low elasticity of the sample. The subsequent period illustrated an inflection in Gꞌ(t) after which significant increase is observed. The gelation time is, by definition, related to the inflection point, which was observed during the growth in elasticity (storage modulus) versus time, 38 herein selected as the time at the inflection point itself. Generally, the shape of this second period differs with the system and test conditions, as evident in figures 3, 7 and 10, wherein the shoulder-like behavior is weakened with shorter separation time (Formulation 2), decrease in the salinity and increase in temperature, respectively. 1000

Storage modulus/ Pa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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F2- Ethomeen T/12 3 vol % Ethomeen T/12 9 wt % PAM 1 wt % PEI Filed water 120 ℃ (248 ℉) 3.45×106 Pa (500 psi)

100

Inflection point2

10

Systems 1

Emulsified polymeric gels Polymeric gels Inflection point1

0.1 0

50

100

150

200

250

300

350

Time/ minutes Figure 2. Storage modulus of polymer gels and emulsified gels


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As shown in Fig. 2, the inflection point (gelation time) for polymeric gel was ~72 minutes, whereas the emulsified gel took more time (~ 98 minutes). Moreover, a slight increase in Gꞌ(t) was detected in the last period, in which a plateau (final equilibrium value) is accomplished. The equilibrium storage modulus (Ge') has slightly decreased from 749 Pa to 715 Pa (i.e. ~ 5% decrease). This increase in the gelation time and the decrees in gel strength can be explained through the kinetics of the cross-linking reaction. It has been reported that the gel strength, which is reflected in Gꞌ, depends on the cross-link density. The gel strength was predicted to increase with the increase in temperature.48,49 This is due to the increase in the cross-linking density; hence, more cross-links are formed. In the case of the emulsified system, a lower cross-linking density was inferred. This may be due to the presence of the PAM/PEI as emulsified into the oleic phase since most of the torque in concentric cylinder geometry is picked at the outer radius which is filled with the nongelling. This will be the case until the breakage of the emulsified system; thereafter a higher crosslinking density will be achieved. Hence, emulsification slows down the cross-linking process. Moreover, in case where the gelation starts before the breakage, formation of discontinuous domains of isolated pocket of gels is expected and more reduction in gel strength is expected. This phenomenon can be seen as shown in Fig. 3(a) and (b), the effect of emulsification is more pronounced when more stable emulsified system was studied: Formulation 1. Two emulsified gels were prepared with different separation time (F1- Ethomeen T/12 and F2- Ethomeen T/12). The first formulation did not separate during the test period while the second formulation has completely separated after one hour. When F1- Ethomeen T/12was used to prepare the emulsified system instead of F2- Ethomeen T/12, the equilibrium storage modulus (Ge') has decreased from 746 Pa to 343.6 Pa (i.e. ~ 54% decrease). Moreover, retardation of the crosslinking process was noticed, wherein the gelation time has increased from 104 to 200 minutes. Therefore, it could be concluded that emulsification slows down the gelation rate and reduces the gel strength. However, if the emulsified system completely breaks, the final gel strength would be higher. Therefore, the control of separation time is not only necessary to avoid gelation in the tubing system but to achieve the optimal gel strength that will provide effective blockage for reservoir water stream production. Thus, it is expected that F2- Ethomeen T/12 is better in minimizing the effect of emulsification on the gel strength, and the gelation time is controlled through retarder addition to avoid premature gelation as discussed later.



1000

Storage modulus/ Pa

3 vol % Ethomeen T/12 9 wt % PAM 1 wt % PEI Field water 120oC (248oC) 500 psi (34.47 bar)

100

10

Formulation, 1

F1-Ethomeen T/12 F2-Ethomeen T/12

0.1 0

100

200

300

400

500

600

700

800

Time/ minutes Figure 3a. Effect of emulsification, on storage modulus for F1- Ethomeen T/12, with no separation during the test period, and F2- Ethomeen T/12 complete separation after one-hour

(a)

Continues gel phase

Isolated gels domain

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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(b)

(c)

Figure 4b. Types of formed gels (a) Severe case of isolated gels domains (formulation with no separation), (b) Mild case of isolated gels domain (formulation with intermediate separation) and (c) continues gel phase (formulation with complete separation)


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Moreover, Stavland et al.34 suggested that lower cross-linking rate in the emulsified form is likely to be a result of the partial dissolution of the cross-linker into the oleic phase, yet to be proven. Thus, this hypothesis was further tested in the current study by using FTIR (Bruker Tensor27, UK). Samples were tested for traces of PEI functional group (amine) in the diesel phase of the separated emulsified gels. Two emulsified PAM/PEI were prepared using two surfactants Armac ANSC (CRV) and Ethomeen T/12. FTIR measurements were performed at ambient condition on pure PEI, PAM, surfactants, and diesel. Then the separated diesel from the two samples was tested. A trace of amine functional group in the separated diesel, if present should appear as a broad peak in the range of 3100-3500 cm-1 wavenumber. However, no indication of trace amine was noticed as shown in Fig. 4, which renders Stavland et al.34 proposed explanation invalid. Recently, a better reasoning has been derived from studying the reaction kinetics of the emulsified PAM/PEI using differential scanning calorimetry (DSC) measurements. Our research group has reported in that DSC study that the cross-linking density of the emulsified gel is almost five times lower than regular polymeric gels. This is believed to be due to the presence of the gelant emulsified in a nongelling oleic phase, which results in less heat conducted to the gelant, leading to a slower reaction rate, thus the lower density of crosslinking.35 A summary of the results of the storage moduli for polymeric gels and emulsified polymeric gels obtained from this study and previous literature reports is given Table 2. In this study, the preparation of the emulsified gel involved using PAM (2 – 4 $/kg), which is more cost-effective compared to the current emulsified gel system prepared using PAtBA (7$/kg) in the oilfields for water control applications.34 Additionally, the choice of PAM and PEI was credited to have good thermal stability and blocking effectiveness.37 Moreover, the reduced gel strength emulsification is clearly evident in Table 2, when comparing non-emulsified system even at low polymer loading of 7/ 0.3 wt% PAM/PEI (Ge' = 1087 Pa) to emulsified system with high polymer loading of 9/1 wt% PAM/PEI (Ge' = 1035 Pa), Also, the storage modulus was found to increase with the temperature increase as will be discussed later.



1.1

1

0.9

Transmittance/ %

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47

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0.8

0.7

0.6

0.5

Pure Diesel Diesel* Diesel** Armac ANSC(CRV) Ethomeen PEI PAM

Amine functionlal group region

0.4

0.3 4000

3500

3000

2500

2000

1500

1000

500

Wavenumber/ cm-1 *Separated from F2- ANSC (CRV) of emulsified (9/1 wt%) PAM/PEI prepared using 0.35 vol % ANSC (CRV) ** Separated from F2- Ethomeen T/12 of emulsified (9/1 wt%) PAM/PEI prepared using 3 vol % Ethomeen T/12

Figure 5. FTIR Spectroscopy at ambient conditions of (i) separated oleic phase (diesel) from two emulsified PAM/PEI samples prepared with two types of surfactant, and (ii) pure diesel, surfactants, PAM and PEI as references


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Table 2. Comparison of the gel strength (storage modulus) reported in the literature for polymer gels and emulsified gels

System

Polymer Gels

Crosslinker Type

Curing Temp. (℃)

Acrylamide and t-butyl acrylate

PEI

25

PAM (7 wt%)

PEI (0.3 wt%)

PAM (9 wt%)

PEI (1 wt%)

Polymer Type

Acrylamide Emulsified and t-butyl acrylate polymer gels PAM (9 wt%) PAM (9 wt%)

Curing Measurement Pressure, Temp. (℃) (Pa)

N/A*

90

Geꞌ, (Pa)

Reference

N/A*

Stavland et al. (2006)34

150

3.45×10

6

150

1087

El-Karsani et al. (2014)37

120

3.45×106

120

885

This study

PEI

25

N/A*

90

N/A*

Stavland et al. (2006)34

PEI (1 wt%)

120

3.45×106

120

733

This study

PEI (1 wt%)

150

3.45×106

150

1035

This study

*Data not available Influence of the Emulsifier Type To study the influence of the emulsifier type, two different surfactants were used to form emulsified gel. Ethomeen T/12 of 3 vol% and ANSC (CRV) of 0.35 vol% were used to emulsify the gelants into the diesel. These concentrations were found to be the minimum dose that will form stable W/O emulsion with a separation time of about one hour at 120 ℃ (248 ℉). This separation time was enough for gelant placement in a typical gas reservoir.35 The gelants were prepared at PAM/PEI concentrations of 9/1 and 7/1 wt%. Fig. 5 shows that no significant change was noticed when ANSC (CRV) was used to prepare the emulsion in comparison with Ethomeen T/12. When ANSC (CRV) was used instead of Ethomeen T/12, an increase in Ge′ from 634 Pa to 673 Pa was obtained at a gelant concentration of 9/1 wt%, while an increase in Ge′ from 597.2 Pa to 630 Pa was observed at a gelant concentration of 7/1 wt%. This slight increase may be related to the 13 ACS Paragon Plus Environment


emulsifier concentration and type, surfactant with some functional group believed to slow down the crosslinking process.35 Further, investigation is required. 1000

Storage modulus/ Pa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

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Formulation 2 Field water NaCl 120 ℃ (248 ℉) 3.45×106 Pa (500 psi)

100

10 Surfactants (Emulsifiers), (9 PAM / 1PEI ) wt % - ANSC(CRV)

1

(9 PAM / 1PEI ) wt % - Ethomeen T/12 (7 PAM / 1PEI ) wt % - ANSC(CRV) (7 PAM / 1PEI ) wt % - Ethomeen T/12

0.1 0

100

200

300

400

500

Time/ minutes

Figure 6. Effect of emulsifier on storage modulus, at different polymer concentration, here Formulation 2 (Complete Separation) was used, that is F2- Ethomeen T/12 and F2- ANSC (CRV)

Influence of Polymer Concentration It was reported in the literature that Ge′ depends on polymer and cross-linker concentration in both organically 37,38 and inorganically cross-linked polymer gels.40,50 To study the impact of polymer concentration, two different gelants were prepared in FMW and SW with PAM of 9 and 7 wt%, with PEI of 1 wt%. A high Gꞌ(t) was observed with the increase in PAM concentration. This increase was associated with the fact that more cross-linkable sites will be accessible for PEI. As shown in Fig. 6, Ge′ increased with increasing polymer concentration, which is in conformity with the data noted for inorganically cross-linked gels24,51 and organically cross-linked systems37,38 as well. From Fig. 6 and in the case of field water, when PAM concentration was increased from 7 to 9 wt%, Ge′ increased from 579 to 634, whereas for seawater the same increase in concentration resulted in an increase in Ge′ from 465 Pa to 508 Pa, respectively. This is likely due to the differences in salinities, which will be discussed below. Hence, the production of a gel with higher


Page 15 of 30

Ge′ requires higher PAM loading. However, higher PAM concentrations resulted in shorter gelation times. Therefore, in treating deeper reservoirs in which higher gelation time is required, these two effects should be taken into consideration. 1000

100

Storage modulus/ Pa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


F2- Ethomeen T/12 3 vol % Ethomeen T/12 120 ℃ (248 ℉) 3.45×106 Pa (500 psi) 10

PAM/PE1, (9/1) wt% in Field water (7/1) wt% in Field water (9/1) wt% in Sea water (7/1) wt% in Sea water

1

0.1 0

50

100

150

200

250

300

350

400

450

Time/ minutes Figure 7. Effect of polymer concentration on storage modulus, at different salinity

Influence of Water Salinity Representative compositions of field and seawater were used to examine the impact of salinity. PAM of 7 and 9 wt% and PEI of 1 wt% were used in the preparation of the gelant. It has been perceived that the increase in water salinity resulted in a decrease in the storage modulus. As illustrated in Fig. 7, in the case of 9/1 (PAM/PEI) wt%, Ge' values were 654.5 Pa and 842Pa for sea and field water samples, respectively. Whereas, in the case of 7/1 PAM/PEI, G e' values were 510 Pa and 697 Pa for sea and field water, respectively. This indicates that seawater reduces Ge' by a factor of almost 1.3. Generally, the gelation time was increased, and gel strength was decreased by increasing water salinity. This observation was confirmed in previous literature reports.52-55However, the increase of salts is well-known to increase the degree of hydrolysis, that is more carboxylate groups will be present in the solution, which results in reduction in the gelation time and increase in the gel strength.32 However, the influence of divalent cations which attract to 15 ACS Paragon Plus Environment


the negative groups is more dominant. In addition, the known shrinkage in polymer (PAM) chain caused by salts addition could limit the access to the carbonyl groups.52 Seawater has a higher salinity than field water and it is true that more carboxylate groups should be available for crosslinking but due to the net effect of polymer shrinkage and the presence of divalent cations negative groups will not be accessible to PEI leading to a decrease in the number of available cross-linkable sites and consequently low elasticity (stored energy). This is working in tandem with that ability of salt cations on screening those negatively charge carboxylate groups, more specifics for the later mechanism can be found in the literature, 56 which will eventually decrease in gel strength and increase the gelation time due to the reduction in the cross-linking rate. The negative impact of salinity on G' was also noticed in inorganically cross-linked gels.44 1000

F2- ANSC (CRV) 0.35 vol % ANSC(CRV) 120 ℃ (248 ℉) 3.45×106 Pa (500 psi)

100

Storage modulus/ Pa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 16 of 30

10 PAM/PEI in Water type, (9/1) wt% in Field water 1

(9/1) wt% in Sea water (7/1) wt% in Field water (7/1) wt% in Sea water

0.1 0

100

200

300

400

500

600

Time/ minutes Figure 8. Effect of mixing water salinity on storage modulus, at different polymer concentration (i.e. 7/1 to 9/1 wt % PAM/PEI)

Influence of Retarders Salts delay the gelation process and consequently reduce gel strength and longer heating times may be needed to reach the same ultimate gel strength. Furthermore, NH4Cl is established to be more successful than NaCl in hindering the cross-linking process of non-emulsified gels.37 This is 16 ACS Paragon Plus Environment

Page 17 of 30

associated with the charge screening effect by cations, present in the salt, on carboxylate groups produced from PAM hydrolysis.56,57 Na+ was reported to have weaker bondage to carboxylate groups when compared to NH4+.58,59 Consequently, NH4+ reduces the sites on the polymer available for cross-linking with PEI. For the influence of retarder type, the same mass concentration of NaCl, and NH4Cl 6,000 mg·L-1 (50 lb / 1000 gal) was included in a polymer solution containing 9 wt% PAM and 1 wt% PEI. The effect of salts was examined in field water as presented in Fig. 8. When NaCl was added Ge' of 703 Pa was measured, whereas almost no change was observed when NH4Cl was added Ge' of 638 Pa was measured. However, NH4Cl was observed to be very effective in delaying the gelation, which concurs with what was described in the literature.37 The relation between the gelation time, tG and NaCl concentration was correlated in the following form tG = a.eb.[C] as given in Fig. 9, where C is the chloride concentration in thousands of mg·L-1, a = 49.616 and b = 0.0232 are constants. When NaCl concentration is increased from zero to 43.14×103 mg·L-1 (360 lb/ 1000 gal) at a constant temperature, the gelation time increased from 50 to 135 minutes (64% increase). The focus here was to study the effect of the Na+ due to its abundance in saline waters used in preparing emulsions in oilfields, like field mixing water, sea water, formation water.

1000

F2- ANSC (CRV) 0.35 vol % ANSC(CRV) PAM/PEI Field water 120 ℃ (248 ℉) 3.45×106 Pa (500 psi)

100

Storage modulus/ Pa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


10

Retarders in PAM/PEI NH4Cl in (7/1) wt% NaCl in (7/1) wt% NH4Cl in (9/1) wt% NaCl in (9/1) wt%

1

0.1 0

50

100

150

200

250

Time/ minutes


300

350

400


Figure 9. Effect of retarder on storage modulus, at different polymer concentration (i.e. 7/1 to 9/1 wt % PAM/PEI)

150 130 Gelation time/ minutes

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 18 of 30

tG = 49.616e0.0232[C] R² = 0.9997

110 90 70

F2- ANSC (CRV) 0.35 vol % ANSC(CRV) 9/1 wt% PAM/PEI 120 ℃ (248 ℉)

50 30 10

0

10

20

30

40

50

NaCl/ 1000 mg·L-1 Figure 10. Gelation time as function of NaCl concentration at 120 ℃

Influence of Temperature To examine the temperature effect on gel strength, three solutions were prepared at ambient temperature containing 9 wt% PAM /1 wt% PEI. Then, gel strength was measured in the range 120o to 150 ℃ (248 to 302 ℉). The gel strength, which is reflected in Gꞌ, depends on the crosslinks density. The gel strength was predicted to increase with temperature.47-49 As shown in Fig. 10, the shape of the second period differs with temperature. The shoulder shape weakens with increasing temperature. The same trend was observed in PAM/PEI in the same range of temperature37 and PAM / Cr+3 cross-linked gels24 in which the gelation was studied in the temperature 24-60 ℃ (75-140 ℉). This can be explained through the kinetics of the cross-linking reaction. Higher temperatures could lead to an increase in molecular mobility; hence, more crosslinks are formed. Consequently, the reaction rate will be enhanced. Another possible explanations are that higher temperatures could (i) result in new cross-links formation or (ii) lead to an increase in PAM hydrolysis, which accelerates cross-linking. With the increase in temperature from 120 ℃ 18 ACS Paragon Plus Environment

Page 19 of 30

(248℉) to 150 ℃ (302 ℉), the equilibrium elastic modulus (Ge') has increased from 733 Pa to 1034 Pa (i.e. 29%) or a factor of 1.41. This increase in Ge' with temperature is due to the increase in the cross-linking.

1000

Storage modulus/ Pa

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


F2- ANSC (CRV) 0.35 vol % ANSC(CRV) 9 wt % PAM 1 wt % PEI Field water 3.45×106 Pa (500 psi)

100

10

Temperature, ℃, 120

130

150

1 0

50

100

150

200

250

300

350

400

Time/ minutes Figure 11. Effect of temperature on storage modulus

Gelation kinetics The gelation kinetics of the emulsified PAM/PEI formulation 2 (complete separation) is examined under isothermal conditions, and the rheological data is analyzed using an Avrami based model introduced by our group.35,60 The model is described below: 𝒍𝒏(− 𝒍𝒏(𝟏 − 𝒙𝒕 )) = 𝒎𝒍𝒏𝒕 + 𝒍𝒏𝒌

(1)

where, t is the gelation time, k is the gelation rate constant, m is an Avrami exponent associated with the nucleation (here cross-linking) mechanism, and xt is the fractional gelation as defined by El-Karsani et al.60 The fractional gelation, xt, is defined as follows: 𝒙𝒕 = 𝑮,𝒕 − 𝑮,𝟎 ⁄𝑮,𝐞 − 𝑮,𝟎 Where 𝐺𝑜′ 𝑎𝑛𝑑 𝐺𝑡′

(2)

are the storage moduli at the onset of gelation (t=0) and at any time t,

respectively; and 𝑮,𝐞 is the ultimate equilibrium gel modulus. 𝐺𝑒′ is the steady state value of the storage modulus (the plateau of the gelation curve). The results of the analysis of the isothermal gelation data for emulsified PAM/PEI at different temperatures are shown in Fig. 11. From the 19 ACS Paragon Plus Environment


Avrami based analysis, the values of m are calculated as: 1.2 at 150 ℃; 1.3 at 130 ℃ and 1.31 at 120 ℃. The rate constant, k, is calculated and found to be 4.1×10-5 min-1, 0.81×10-5 min-1 and 0.39×10-5 min-1 at 150 ℃, 130 ℃ and 120 ℃, respectively. This indicate that the cross-linking

3.5 3 2.5 2

ln(–ln(1–x))

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Page 20 of 30

150 130 120 Linear (150) Linear (130) Linear (120)


1.5 1 0.5 0 -0.5 -1 -1.5 9.07

9.12

9.17

9.22

9.27

lnt Figure 12. Avrami plots for emulsified PAM/PEI at different temperatures in the isothermal regime

(gelation) rate in field water at 150 ℃ is 10.5 times faster than at 120 ℃. Furthermore, Arrhenius equation is used to calculate the activation energy, E, from the temperature dependence of the rate constant, k: 𝑬

𝒌(𝑻) = 𝒌𝟎 𝒆(− 𝑹𝑻)

(3)

Where ko is the Arrhenius frequency factor, E is the Activation energy, and R is the universal gas constant (8 J mol-1 K-1). The activation energy is obtained as 109kJ mol-1. The rate constant, k, is found to increase with the increase in temperature as shown in Fig. 12. The value of the activation energy for non-emulsified 9/1 wt% PAM/PEI is calculated, at almost similar condition of temperatures (80, 100, and 120 ℃) (see60) and found to be about 10 kJ mol-1. The increase (109kJ 20 ACS Paragon Plus Environment

Page 21 of 30

mol-1 to 10 kJ mol-1) in the activation energy is believed to be a consequence of the emulsification; wherein the reaction is retarded due to the heat transfer limitations as detailed earlier. This shows that the gelation in the emulsified system requires extra energy (~ ten-times) to attain an equal conversion as the non-emulsified gels.

-10

-11

ln(k)

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


-12


-13 0.00235

0.0024

0.00245

0.0025

0.00255

0.0026

Inverse Temperature/ K-1

Figure 13. Reaction rate constant as function of temperature

Conclusion The influence of emulsification, emulsifier type, separation time, polymer concentrations, temperature, the salinity of mixing water and type of salt on gelation kinetics and gel strength of emulsified PAM / PEI system were studied at high temperatures (>100 ℃). The gel strength was measured using high-pressure dynamic shear rheometry. For the first time, gelation kinetics and gel strength of emulsified PAM/PEI gels are reported. The main findings of this work are as follow:

1. Emulsification slows down the cross-linking process; this behavior is tentatively explained by formation of isolate gels domains and the limitations of heat transfer to the emulsified gel due to the presence of the oil layer.



Page 22 of 30

2. A lower rate of cross-linking was observed for emulsified PAM/PEI in comparison with the non-emulsified system. This effect is more pronounced in the stable emulsified PAM/PEI formulation (9/1) wt% where the elastic modulus at 120 ℃ has decreased by 54%. For unstable emulsified PAM / PEI formulation (9/1) wt%, with complete separation within one hour, the drop in the elastic modulus was insignificant (~ 5%). 3. In general, the emulsifier type (i.e. family group) has no significant influence on the gelation kinetics and gel strength of emulsified gels. No significant impact was observed when acetated amine (ANSC (CRV)) was used instead of ethoxylated amine (Ethomeen T/12) as an emulsifier, although different concentrations were employed.

ANSC (CRV) RD is

recommended for field applications due to its low cost and low dosage required to achieve the optimal formulation. 4. The storage modulus of the emulsified PAM / PEI (9/1) wt% was found to increase by about 29% when the temperature was increased from 120 ℃ (248 ℉) to 150 ℃ (302℉). 5. Generally, the storage modulus decreased in the presence of salts. High water salinities resulted in low gel strength and longer gelation time. 6. NH4Cl was more successful than NaCl in the hindering of the cross-linking process of emulsified gels and can be used to control the gelation time in field applications. This is because NH4Cl is more effective than NaCl in screening the negative charges on the carboxylate groups. Consequently, it reduces the available sites on the polymer to cross-link with PEI. A correlation is provided for the dependency of the gelation time on salt concentration. 7. Emulsified PAM/PEI gelation kinetics during the isothermal process was analyzed using Avrami based model, and the activation energy for emulsified gels was found to be ~10 times higher than non-emulsified gels. 8. The cross-linking rate in the field water at 150 ℃ is found to be almost 12 times faster than at 120 ℃.

ACKNOWLEDGEMENTS


Page 23 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


King Abdul-Aziz City for Science and Technology (KACST) is acknowledged for supporting this research through project # AR-30-291. KFUPM, Saudi Aramco, and Qatar University are also acknowledged for their support.

References (1) Khatib Z.; Verbeek P. Water to Value-Produced Water Management for Sustainable Field Development of Mature and Green Fields. J. Pet. Technol. 2003, 55, 26–8. (2) Ahmed, Q. A.; Mohamed, A.; Salah, R.; Bakhit, A. Risk Analysis and Decision Making in Relative Permeability Modifier Water Shut-off Treatment. SPE 2010, DOI:10.2118/126845MS. (3) Veil, J. A.; Clark, C. E. Produced Water Volumes and Management Practices in the United States.

Report

for

U.S.DOE,

National

Energy

Technology

Laboratory,

http://www.netl.doe.gov/technologies/coalpower/ewr/water/pdfs/anl%20produced%20water %20volumes%20sep09.pdf. Retrieved 1 Sep 2009. (4) Veil, J. A.; Puder, M. G.; Elcock, D.; Redweik, R. J. A. Whitepaper Describing Produced Water from Production of Crude Oil, Natural Gas, and Coal Bed Methane. http://www.ead.anl.gov/pub/doc/ProducedWatersWP0401.pdf. Retrieved 21 March 2010. (5) Baily, B.; Crabtree, M.; Tyrie, J. Water control. Oilfield Rev 2000, 12, 30–51. (6) Khatib, Z. Produced Water Management in MENA Region: is it a Legacy or an Opportunity for IOR/EOR Field Development. International Petroleum Technology Conference 2007, doi:10.2523/11624-MS. (7) U.S. Department of energy. A white paper describing produced water from production of crude oil, natural gas, and coal bed methane. 2004. (8) Dal Ferro, B.; Smith M. Global onshore and offshore water production. Oil & Gas Review OTC Edition 2007. (9) Hibbeler, J.; Rae P. The environmental benefits of reducing water production. Asia Pacific health, safety, and environment conference and exhibition, Kuala Lumpur. SPE 2005, doi:10.2118/96582-MS.



(10)

Page 24 of 30

Donham, J. E. Offshore Water Injection System: Problems and Solutions. Offshore

Technology Conference 1991, doi:10.4043/6782-MS. (11)

Merdhah, A. B. B.; Yassin, A. A. M. Scale Formation Due to Water Injection in Malaysian

Sandstone Cores. J. Applied Sci 2009, 9 (18), 3298-3307. (12)

Al-Tolaihy, M.; Bukhari, D. O.; Wu A. M. Study on the optimization of de-Scaling

operations in Saudi Arabian Khuff Gas Wells. NACE International 2010. (13)

Adewunmi, A. A. ;

Ismail, S.; Sultan, A. S. Crosslinked Polyacrylamide Composite

Hydrogels Impregnated with Fly Ash: Synthesis, Characterization and Their Application as Fractures Sealant for High Water Producing Zones in Oil and Gas Wells. J Polym Environ 2018, 26 (8), 3294 –3306. doi:10.1007/s10924-018-1204-9 (14)

Vasquez, J.; Civan, F.; Shaw, T. M.; Dalrymple, E.D.; Eoff L.; Reddy, B. R.; Brown, D.

Laboratory evaluation of high-temperature conformance polymer systems. SPE production and operations symposium, Oklahoma City. SPE 2003, doi:10.2118/80904-MS. (15)

Zaitoun, A.; Kohler, N. 1. Two-phase flow through porous media: effect of an adsorbed

polymer layer. SPE annual technical conference and exhibition, Houston, SPE 1988, doi:10.2118/18085-MS. (16)

Seright,

R.

S.

Disproportionate

Permeability

Reduction

with

Pore-Filling

Gels.

SPEJ, Soc. Pet. Eng. J. 2009, 14, 5 –13.

(17)

Lei, G.; Li, L.; Nasr-El-Din, H.A. New gel aggregates to improve sweep efficiency during

water flooding. SPE Reservoir Eng. 2011, 14,120–8. (18)

Heshmati, M.; Hossein, M.; Manouchehr, H.; Torabi, M. Visualization of polymer

flooding in heterogeneous system using glass micromodels. JUST 2007, 33 (2), 25-32 (19)

Qin, T.; Javanbakht, G.; Goual, L.; Piri, M.; Towler, B. Microemulsion-enhanced

displacement of oil in porous media containing carbonate cements. Colloids and Surfaces. 2017, 530, 60-71. (20)

Javanbakht, G.; Arshadi, M.; Qin, T.; Goual, L. Micro-scale displacement of NAPL by

surfactant and microemulsion in heterogeneous porous media. Advances in Water Resources 2017, 105, 173-187.


Page 25 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(21)

Heshmati, M.; Piri, M. Interfacial boundary conditions and residual trapping: A pore-scale

investigation of the effects of wetting phase flow rate and viscosity using micro-particle image velocimetry. Fuel 2018, 224, 560-578. (22)

Mingliang, L.; Xiaodong, S.; Yu, Z.; Zhenhe, Y.; Daoyong, Y.; Jun, G. Performance

Evaluation of Water Control with Nanoemulsion as Pre-pad Fluid in Hydraulically Fracturing Tight

Gas

Formations.

Energy

Fuels

2017,

31

(4),

3698–3707.

DOI:

10.1021/acs.energyfuels.6b03291 (23)

Jingyang, P.; Jia, Z.; Yashu, C.; Baojun, B. Development of Thermotransformable

Controlled Hydrogel for Enhancing Oil Recovery. Energy Fuels 2017, 31 (12), 13600–13609. DOI: 10.1021/acs.energyfuels.7b03202 (24)

Sydansk, R. D. A newly developed chromium (III) gel technology. SPE Reservoir Eng.

1990, 5, 346–52. (25)

Lockhart TP. Chemical Properties of Chromium/Polyacrylamide Gels. SPEJ, Soc. Pet. Eng.

J. 1994, 2, 199-205.

(26)

Morgan J. C.; Smith P. L.; Stevens, D. G. Chemical adaptation and deployment strategies

for water and gas shut-off gel systems. the Royal Chemistry Society’s chemistry in the oil industry international symposium, Ambleside 1997. (27)

Moradi-Araghi, A. A review of thermally stable gels for fluid diversion in petroleum

production. SPEJ, Soc. Pet. Eng. J. 2000, 26, 1–10. (28)

Albonico, P.; Bartosek, M.; Lockhart T. P.; Causin, E. New Polymer Gels for Reducing

Water Production in High-Temperature Reservoirs. European Production Operations Conference and Exhibition, Aberdeen, United Kingdom. 1994, doi:10.2118/27609-MS. (29)

Hutchins RD, Dovan HT, Sandiford BB. Field Applications of High Temperature Organic

Gels for Water Control. SPE/DOE Improved Oil Recovery Symposium, Tulsa, Oklahoma. 1996, doi:10.2118/35444-MS. (30)

Hardy, M.; Botermans, W.; Hamouda, A.; Valdal, J.; Warren, J. The First Carbonate Field

Application of a New Organically Crosslinked Water Shutoff Polymer System. SPE International

Symposium

on

Oilfield

Chemistry,

doi:10.2118/50738-MS.


Houston,

Texas.

SPE

1999,


(31)

Daoyi, Z.; Baojun, B.; Jirui, H. Polymer Gel Systems for Water Management in High

Temperature Petroleum Reservoirs: A Chemical Review. Energy Fuels 2017, 31 (12), 13063– 13087. DOI: 10.1021/acs.energyfuels.7b02897 (32)

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. Society of Petroleum Engineers. SPEJ 2014, 19 (1), doi:10.2118/163100-PA. (33)

Mohamed A. Development of Emulsified gels for Water control in Oil and Gas Wells,

department of Petroleum Engineering, KFUPM, M. Sc. Thesis 2014. (34)

Stavland, A.; Andersen, K. I.; Sandoey, B.; Tjomsland, T.; Mebratu, A. A. How to apply a

blocking gel system for bullhead selective water shutoff: from laboratory to field. SPE conference. SPE 2006, doi:10.2118/99729-MS. (35)

Mohamed, A.I.A.; Hussein, I. A.; Sultan A. S.; El-Karsani K. S. M.; Al-Muntasheri G. A.

DSC investigation of the gelation kinetics of emulsified PAM/PEI system Influence of surfactants and retarders. J Therm Anal Calorim 2015. 122,1117-1123.

(36)

Mohamed, A.I.A.; Hussein, I. A.; Sultan A. S.; Al-Muntasheri G. A. Use of organoclay as

a stabilizer for water-in-oil emulsions under high-temperature high-salinity conditions. J Petrol Sci Eng 2018, 160, 302-312. (37) El-karsani K. S. M.; Al-Muntasheri G. A.; Sultan A. S.; Hussein I. A. Gelation of a WaterShutoff Gel at High Pressure and High Temperature: Rheological Investigation. SPEJ, Soc. Pet. Eng. J. 2014, 20 (5), 1103 - 1112. (38)

Al-Muntasheri, G. A.; Hussein I. A.; Nasr-El-Din, H. A.; Amin M. B. Viscoelastic

Properties of a High Temperature Cross-linked Water Shut-Off Polymeric Gel. J. Pet. Sci Eng 2007, 55, 56-66. (39)

Yingrui, B.; Chunming, X.; Falin, W.; Junjian, L.; Yong, S.; Dexin, L. Gelation Study on

a Hydrophobically Associating Polymer/Polyethylenimine Gel System for Water Shut-off Treatment. Energy Fuels 2015, 29 (2), 447–458. DOI: 10.1021/ef502505k (40)

Grattoni, C. A.; Al-Sharji, H. H.; Yang, C.; Muggeridge, A. H.; Zimmerman, R. W.

Rheology and Permeability of Cross-linked Polyacrylamide Gel. J. Colloid Interface Sci 2001, 240, 601-607. 26 ACS Paragon Plus Environment

Page 26 of 30

Page 27 of 30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60


(41)

Moakes, R. J. A.; Sullo, A.; Norton, I. T. Preparation and rheological properties of whey

protein emulsion fluid gels. RSC Adv 2015; 5, 60786-60795. (42)

Hussein I. A.; Ho, K.; Goyal, S. K.; Karbashewski, E.; Williams M. C. Thermomechanical

degradation in the preparation of polyethylene blends. Polymer Degradation and Stability 2000, 68, 381-392. (43)

García, B. F.; Saraji S. A new insight into the dependence of relaxation time on frequency

in viscoelastic surfactant solutions : From experimental to modeling study. J. Colloid Interface Sci. 2018, 517, 265-277. doi :10.1016/j.jcis.2018.01.078. (44)

Koohi, A. D.; Seftie, M. V.; Ghalam, A.; Moghadam, A. M.; Sabet, S. Z. Rheological

Characteristics of Sulphonated Polyacrylamide/Chromium Triactate Hydrogels Designed for Water Shut-off. Iran. Polym. J. 2010, 19, 757-770. (45)

Rajkamal, R.; Pathak, N. P.; Chatterjee, D.; Paula, A.; Yadav, S. Arabinose based gelators:

rheological characterization of the gels and phase selective organogelation of crude-oil. RSC Adv 2016, 6, 92225-92234. (46)

Mohamed, A. I. A.; Sultan, A. S.; Hussein, I. A.; Al-Muntasheri, G. A. Influence of

surfactant structure on the stability of water-in-oil emulsions under high-temperature highsalinity conditions. J. Chem 2017, 10.1155/2017/5471376 Article ID 5471376. (47)

Al-Yaari, M.; Hussein, I. A.; Al-Sarkhi, A.; Abbad, M.; Chang, F. Pressure Drop Reduction

of Stable Emulsions: Role of Aqueous Phase Salinity. SPE Saudi Arabia Section Technical Symposium and Exhibition, Al-Khobar, Saudi Arabia. SPE 2013, doi:10.2118/168078-MS. (48)

Kakadjian, S.; Rauseo, O.; Mejias, F. Dynamic Rheology as a Method for Quantify Gel

Strength of Water Shutoff Systems. SPE International Symposium on Oilfield Chemistry, Houston, Texas. SPE 1999, doi:10.2118/50751-MS. (49)

Calvet, D.; Wong, J. Y.; Giasson, S. Rheological Monitoring of Polyacrylamide Gelation:

Importance of Cross-Link Density and Temperature. Macromolecules 2004, 37 (20), 77627771. (50)

Omari, A. Rheological study of the gelation kinetics of the scleroglucan-zirconium system.

Polym Journal 1995, 36 (10), 815-819. (51)

Huang, R.; Cai, W. Study on gelation of partially hydrolyzed polyacrylamide with titanium

(IV). Eur. Polym. J. 2001, 37, 1553–9.



(52)

Nasr-El-Din, H. A.; Hawkins, B. F.; Green, K. A. Viscosity Behavior of Alkaline,

Surfactant, Polyacrylamide Solutions Used for Enhanced Oil Recovery. SPE International Symposium on Oilfield Chemistry, Anaheim, California. SPE 1991, doi:10.2118/21028-MS. (53)

Broseta, D.; Marquer, O.; Blin, N.; Zaitoun, A. Rheological Screening of Low-Molecular-

Weight Polyacrylamide/Chromium(III) Acetate Water Shutoff Gels. SPE/DOE Improved Oil Recovery Symposium, 3-5 April, Tulsa, Oklahoma. SPE 2000; doi:10.2118/59319-MS. (54)

Broseta, D.; Marquer, O.; Alain, Z.; Baylocq, P.; Fery, J. J. Shear Effects on

Polyacrylamide/Chromium (III) Acetate Gelation. SPEJ, Soc. Pet. Eng. J. 2000, 3, 204-208. (55)

Romero-Zeron, L. B.; Hum, F. M.; Kantzas, A. Characterization of Crosslinked Gel

Kinetics and Gel Strength by Use of NMR. SPEJ, Soc. Pet. Eng. J. 2008, 11, 439– 453. (56)

Tam, K. C.; Tiu, C. Steady and dynamic shear properties of aqueous polymer solutions. J

Rheol. 1989, 33 (2), 257-280. (57)

Ghannam, M. T. Rheological Properties of Aqueous Polyacrylamide Solutions. J. Appl.

Polym. Sci. 1999, 72, 1905-1912. (58)

Kherb, J.; Flores, S. C.; Cremer, P. S. Role of Carboxylate Side Chains in the Cation

Hofmeister Series. J. Phys. Chem. B 2012, 116 (25), 7389-7397. (59)

El Karsani, K. S. ; Al‐Muntasheri, G. A. ; Sultan, A. S. ; Hussein, I. A. Impact of salts on

polyacrylamide hydrolysis and gelation : New insights. J. Appl. Polym. Sci. 2014, 131(23). (60)

El-Karsani, K. S. M. ; Al-Muntasheri, G. A. ; Sultan, A. S. ; Hussein, I. A. Gelation kinetics

of PAM/PEI System : DSC investigation. J Therm Anal Calorim 2014, 116 (3),1409–1415.


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Table of Contents Graphic (TOC) Figure 1. Emulsified Gels generic formulations ........................................................................................... 7 Figure 2. Storage modulus of polymer gels and emulsified gels .................................................................. 8 Figure 3a. Effect of emulsification on storage modulus ............................................................................. 10 Figure 4b. Types of formed gels ................................................................................................................. 10 Figure 5. FTIR Spectroscopy at ambient conditions................................................................................... 12 Figure 6. Effect of emulsifier on storage modulus, at different polymer concentration ............................. 14 Figure 7. Effect of polymer concentration on storage modulus, at different salinity ................................. 15 Figure 8. Effect of mixing water salinity on storage modulus, at different polymer concentration ........... 16 Figure 9. Effect of retarder on storage modulus, at different polymer concentration ................................ 18 Figure 10. Gelation time as function of NaCl concentration at 120 ℃ ...................................................... 18 Figure 11. Effect of temperature on storage modulus ................................................................................. 19 Figure 12. Avrami plots for emulsified PAM/PEI at different temperatures in the isothermal regime ...... 20 Figure 13. Reaction rate constant as function of temperature ..................................................................... 21


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Polyethylenimine under High

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