Study on Various Readily Available Proteins as New Green Scale

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A Study on Various Readily-Available Proteins as New Green Scale Inhibitors for Oilfield Scale Control Mohamed F. Mady, and Malcolm A. Kelland Energy Fuels, Just Accepted Manuscript • Publication Date (Web): 02 May 2017 Downloaded from http://pubs.acs.org on May 4, 2017

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A Study on Various Readily-Available Proteins as New Green Scale Inhibitors for Oilfield Scale Control Authors: Mohamed F. Mady,a,b,* and Malcolm A. Kellanda,**

a

Department of Mathematics and Natural Science, Faculty of Science and Technology,

University of Stavanger, N-4036 Stavanger, Norway

b

Department of Green Chemistry, National Research Centre, 33 El Bohouth st. (former El Tahrir

st.), Dokki, Giza, Egypt, P.O. 12622.

Key words: Proteins, Oilfield Scale, Crystal growth, Scale Inhibitors, Biodegradation

**

Corresponding author at:

Department of Mathematics and Natural Science, Faculty of Science and Technology, University of Stavanger, N-4036 Stavanger, Norway *

Corresponding authors, E-mail addresses [email protected] (M.A. Kelland),

[email protected] (M.F. Mady)

Abstract: A series of natural proteins and partially hydrolyzed proteins (peptones) from various animal and plant sources have been tested for the ability to prevent the formation of barium sulfate and 1

ACS Paragon Plus Environment

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calcium carbonate scaling for use as enviromentally-friendly scale inhibitors (SIs) in the petroleum industry. All SI performance experiments were carried out in a dynamic tube blocking rig at 100oC and 80 bar. Although many of the proteins/peptones showed poor or negligible performance, the milk proteins, casein peptones and tryptones, showed reasonable inhibition performance on sulfate scale although not as good as some commercial non-polymeric aminophosphonate scale inhibitors such as diethylenetriaminepentakis(methylenephosphonic acid) (DTPMP). On calcium carbonate scale Tryptone N1 19553 outperformed DTPMP. In addition, the best proteins/peptones showed excellent calcium compatibility. Thermal ageing studies indicated that the best peptones were not stable for squeeze treatments at 100oC and therefore are best used for topside continual injection. Several attempts were made to derivatize the pendant primary amine (from lysine) or hydroxyl groups in the proteins to increase the number of carboxylate groups or introduce phosphonate or sulfonate groups. Although scale inhibition performance enhancement was achieved this could simply be due to synergistic behavior between an unreacted or hydrolyzed starting material and the protein.

1. Introduction In the water processing industry, the precipitation of sparingly soluble inorganic salts such as calcium and barium as carbonate, sulfate or phosphate, and their adhesion to equipment surfaces is a major problem of mineral scaling.1,2 Carbonate and sulfate scaling in an oilfield are the beginning of a highly complicated and multi-disciplinary concern. The scale can occur anywhere along the production conduit, narrowing the internal diameter blocking flow, and can even occur as far along as the processing facilities.3,4 2


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Many chemicals and antiscalants have been widely reported to mitigate the mineral scaling problems, but the efficiency is often low on both economic and environmental grounds. The most common and effective scale control method is the use of scale inhibitors (SIs). Inhibition or dissolution of scale deposit by the SIs depends on either nucleation and/or crystal growth of the scale.1, 5-7 A series of commercial SIs for carbonate and sulfate scaling are typically polymeric, e.g., polyphosphonates, polyacrylates, polymaleates, polysulfonates, and copolymers thereof. Furthermore, non-polymeric phosphonates antiscalents are effective inhibitors of calcium and sulfate

scale

growth.

For

example,

aminotris(methylenephosphonic

diethylenetriaminepentakis(methylenephosphonic

acid)

acid)

(DTPMP)

(ATMP), and

Diethylenetriaminepentakis(methylphosphonic acid).8-14 Very recently, we have synthesized of several bisphosphonates (BPs), which have been evaluated for carbonate and sulfate scale inhibition in a high-pressure dynamic tube blocking rig at approximately 80 bar and 100°C as shown in Figure 1.15

3


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Figure 1. Some of the promising novel scale inhibitors synthesized within our group.

Commercial SIs do not occur naturally and, therefore most will show resistance to biodegradation. Increasing environmental concerns and discharge limitations has caused scale inhibitor chemistry to move towards “green antiscalants” that readily biodegrade and have minimum environmental impact.16-19 The European Economic Community (EEC) has assigned the Oslo and Paris Commission (OSPARCOM) with the task of preparing and providing environmental guidelines.20 Proteins are known for their specific binding interactions and can interact with a wide range of substrates and synthetic analogues. Proteins are chains of amino acids that fold into a threedimensional shape. Proteins come in a wide variety of amino acid sequences, sizes, and three4


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dimensional structures, which reflect their diverse roles in nearly all cellular functions.21,22 For example, casein is a natural phosphoprotein of milk-extracted and is a rich source of amino acid (Figure 2).23-27 In continuation of our research aimed to find environmentally friendly chemicals for oil and gas industry,15,28 we have evaluated the calcium carbonate and barium sulfate scale inhibition performance of a series of different natural proteins from sources such as milk, meat, gluten, soya and peas using a classic dynamic tube blocking equipment at approximately 80 bar and 100 °C. Such proteins are acceptable for use offshore as they are natural and therefore are easily biodegraded and have negligible impact on environment. We also report studies where we tried to modify the amino proteins, using different chemical routes such as the Moedritzer-Irani29 and other reactions, to improve their scale inhibition performance.

Figure 2. (Left) One of the proposed representations of the model of casein and submicelle. (Right) The primary structure of proteins.

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2. EXPERIMENTAL SECTION 2.1. Chemicals All chemicals were purchased from VWR, Nippon Chemical Industrial Co., Ltd., Tokyo Chemical Industry Co., Ltd. and Sigma-Aldrich. All solvents were used as purchased without further purification. The sodium salts of diethylenetriaminepentakis(methylenephosphonic acid) (DTPMP) and aminotris(methylenephosphonic acid) (ATMP) were obtained from Solvay. Most tested proteins were obtained from Organotechnie S.A.S. France. Whey protein-80% was obtained from Tina, Nærbø, Norway; Nisaplin was obtained from Danisco, Denmark; Sodium caseinate (P5206-1) was obtained from Havero Hoogwegt B.V. Netherlands and Crotein C obtained from Croda Europe Ltd., England. 3-chloropropyliminobis(methylenephosphonic acid) was prepared according to the literature method.30

2.2. Characterization of Scale Inhibitors Nuclear magnetic resonance (NMR) spectra were recorded on a 400 MHz Varian NMR spectrometer in deuterium oxide (D2O). 1H ,13C and 31P chemical shifts were obtained in D2O.

2.3. Synthesis of Scale inhibitors (SIs) Proteins are linear polymers formed by linking the α-carboxyl group of one amino acid to the αamino group of another amino acid with a peptide bond. Lysine (lys) is one of the three amino 6


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acids that have basic side chains at neutral pH. The amino group in lysine is highly reactive and often participates in reactions. Interestingly, the modified lysine was reported as a green scale inhibitor by reacting this amino acid with formaldehyde and phosphorous acid to give L-lysine tetra(methylenephosphonic acid) as shown in Figure 3.31 Therefore, in the following reactions we have modified the amino acids of lysine in Casein Peptone (19544) by different chemical reactions e.g. phosphonation, sulfonation and the reaction of primary amines with different anhydrides.

Figure 3. Lysine (left) and L-lysine tetra(methylenephosphonic acid) (right).

2.3.1. Attempted introduction of phosphonate groups into Casein Peptone Plus 19544 2.3.1.1. Moedritzer-Irani reaction (SI-1) To a 100 ml two-necked Erlenmeyer flask fitted with a thermometer, additional funnel and a magnetic stirring bar were placed appropriate Casein Peptone Plus 19544 (2 g, 1.0 equiv. of lysine), H3PO3 ( 2.0 equiv.) and AcOH (1%) in deionized water (20 ml), flushed with nitrogen 7


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for at least 10 min. Under the protection of nitrogen, the reaction mixture was allowed to heat stepwise from room temperature to 50oC, at which time HCHO (2 equiv.) was added dropwise. The reaction mixture was kept stirred at 70°C for 3 h. The mixture was cooled to room temperature and adjusted the pH in the range of 5 to 6 to approve the efficiency of pH on the scale inhibition. The final crude solution was tested for scale inhibitor experiments in a highpressure dynamic tube blocking rig. It was found that SI-1 showed poor performance against carbonate and sulfate scale compared to the original Casein Peptone Plus 19544 as presented in Table 2. It is hard to control the hydrolysis of proteins under acidic conditions. Therefore, we tried to use 1% of acetic acid instead of hydrochloric acid to avoid hydrolyzing proteins as shown in Figure 4. High-pressure dynamic tube blocking results showed the hydrolysis of proteins into their constituent amino acids. In addition,

31

P NMR analysis of the crude product did not display any peak related to

PO3H2 moiety. 2.3.1.2.

The

reaction

of

Casein

Peptone

Plus

1954

with

3-chloropropyl

iminobis(methylenephosphonic acid): (SI-2) A mixture of Casein Peptone Plus 19544 (2 g, 1.0 equiv. of lysine), 3-chloro propyl imino bis(methylene phosphonic acid) (2.0 equiv.) and deionized water (20 ml ) was added to a 100 ml Erlenmeyer flask fitted with a thermometer under vigorous stirring. The reaction mixture was adjusted to pH = 9 with 50% sodium hydroxide as shown in Figure 4 and kept stirred at room temperature for 0.5 hr and/or heated for 3 hrs at 70oC. We tested the crude product under the both conditions (room temperature and heating) for sulfate and carbonate scale. 8


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2.3.2. Attempted introduction of sulfonate groups into Casein Peptone Plus 19544: (SI-3) To a 50 mLErlenmeyer flask, a mixture of Casein Peptone Plus 19544 (2 g, 1.0 equiv. of lysine), formaldehyde-sodium bisulfite adduct (2.0 equiv.) and 20 ml of deionized water was adjusted to pH = 9 with 50% sodium hydroxide. The solution was then subjected to stirring at room temperature for 0.5 hr and/or heating at 70oC for 3 hrs. The crude product was tested for sulfate and carbonate scale in a high-pressure dynamic tube blocking rig. The route for the synthesis of the new SIs with attached sulfonate moieties is summarized in Figure 4.

2.3.3. Reaction of Casein Peptone Plus 1954 with maleic anhydride: (SI-4) A mixture of Casein Peptone Plus 19544 (2 g, 1.0 equiv. of lysine), maleic anhydride (2.0 equiv.) and 20 ml of deionized water in a 50 mL Erlenmeyer flask was adjusted at pH = 9 with 50% sodium hydroxide. The solution was then subjected to stirring at room temperature for 0.5 hr and/or heating at 70oC for 3hrs. The crude product (Figure 4) was tested for sulfate and carbonate scale in a high-pressure dynamic tube blocking rig.

9


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O HO P HO N

O O HO P P OH HO OH

Page 10 of 29

O OH P OH N

NH

NH

COOH

COOH SI-2

H2O3P

H2O, pH= 8-9

H2O3P

RT. 0.5 hr or 70oC, 3 hrs HO

O

HO O

O

O NH2

NH2 O

NH

HN

O COOH

SI-4

H3PO3 HCHO

O H2O, pH= 9

COOH

Cl

N

RT. 0.5 hr or 70oC, 3 hrs

COOH

COOH

PO3H2

PO3H2

NH

HN

1% AcOH 70oC, 3 hrs

Casein Peptone Plus 19544

COOH

COOH SI-1

HO

SO3Na

H2O, pH= 8-9 RT. 0.5 hr or 70oC, 3 hrs

SO3Na

SO3Na

NH

HN

COOH

COOH

SI-3

Figure 4. Attempted modifications of lysine amine groups in proteins.

10


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2.4. High-Pressure Dynamic Tube Blocking Test Methods Dynamic tube blocking tests to determine relative scale inhibitor performance were carried out on an automated rig (built by Scaled Solutions Ltd., Scotland) at 100oC and 80 bars using a 1mm internal diameter 316 steel test coil. Both calcium carbonate and barium sulfate scale inhibition were investigated. Details of the test procedure have been given previously.32 The highest test scale inhibitor concentration, used in some but not all tests, was 100ppm and the lowest concentration investigated was 1ppm. The concentration at which rapid tube blocking occurs was taken as the fail inhibitor concentration (FIC) of the scale inhibitor. This is to avoid confusion with the operational use of the abbreviation MIC, which is the minimum inhibitor concentration which prevents scale formation.

Figure 5 shows a typical graph obtained from a single run of the dynamic tube blocking rig, showing, in chronological order, a blank test with no inhibitor, a test to determine the FIC, a repeat FIC test and finally a repeat blank test. In the example in Figure 5, we injected scale inhibitor at 50 ppm, 20, and 10 ppm for 1 h each. After 40 min at 10 ppm (i.e. 194 min on the logger) rapid scale formation occurred. After cleaning of the coil, the repeat scale inhibitor test was carried out but starting from 20 ppm, which is at 214 min on the logger. After 34 min at 10 ppm (307 min on the logger), scale formed rapidly again. This shows that the reproducibility of the experiments is very good which was true for all experiments in this study. The final stage of the experiment was a new blank test without added inhibitor. In this case, the second blank scaling time was 19 min. We have found that the time for scaling in the second blank test is 11


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normally a little longer than the first blank test, both for carbonate and sulfate scaling. This may be due to the time needed to flush out the distilled water cleaning fluid in the system, which is not present in the first blank test. Before the first blank test, we flushed the scaling brines, one at a time, to check for good flow in the system.

Figure 5. A pressure-time graph showing the four stages of a scale inhibitor test. For this study, we chose to use model fluids based on production from the Heidrun oilfield, Norway. The composition of aqueous produced fluids from this field is given in Table 1. We used 50/50 volume mixture of formation water and synthetic seawater to produce barium sulfate scaling. Brines were degassed for 15 min using a vacuum pump to remove dissolve gas that might cause a pump to stop brine injection due to gas bubbles in the line.

12


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Table 1. The composition of Heidrun formation water, seawater, and a 50/50 mixture.

Ion

Heidrun formation water

Seawater (ppm)

(ppm)

50/50 Mixed brine (ppm)

Na+

19,510

10,890

15,200

Ca2+

1020

428

724

Mg2+

265

1368

816.5

K+

545

460

502.5

Ba2+

285

0

142.5

Sr2+

145

0

72.5

SO42-

0

2960

1480

HCO3-

880

120

500

2.5. Hydrothermal Stability Test A 20 wt.% additive solution in deionized water is nitrogen-sparged for 1 hour and placed in a pressure tube. It is then sparged again with nitrogen to minimize head space oxygen in the tube before heating at 100°C for one week. The resultant solution is then checked for efficacy in the sulfate and carbonate scale dynamic scale loop test.

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3. RESULTS AND DISCUSSION Mineral scales often form in oil wells and pipelines due to inorganic salt supersaturation. Most common scales contain carbonate, sulfate or sulfide salts of divalent metal ions (Ca2+, Sr2+, Ba2+ and Fe2+).1 There is increasing focus on using environmentally-friendly scale inhibitors (SIs) to approve the offshore regulations (OSPARCOM) for oilfield chemicals but few inhibitors show good biodegradability as well as containing phosphorus. It is well-known that phosphorylated proteins play an efficient role to control apatite nucleation, crystal growth, and inhibition of scale formation.33 Casein is the main natural phosphoprotein found in milk. Proteins are biopolymers and are a rich source of both phosphate groups and acidic amino acid. Moreover, it was reported that the strong binding of phosphate groups of casein to the calcium ions on the CaCO3 surface play an important role in the formation and stabilization of vaterite.34 Table 2 summarizes the fail inhibition concentration (FIC) for a series of commercial phosphorylated and/or non-phosphorylated proteins in dynamic SI tests on sulfate scale. This includes milk proteins (casein peptones, casein tryptones, whey, Nisaplin, sodium caseinate); meat proteins (meat peptone, gelatine peptone, protein C) and plant proteins (wheat, gluten, potato, soy and pea peptones), as well as two commercial SIs DTPMP and ATMP. Inhibition test results of these SIs for carbonate scale are given in Table 3. Furthermore, other modified proteinbased SIs have been tested for sulfate and carbonate scale inhibition and these are also shown in Tables 2 and 3.

14


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SIs were injected at concentrations of 100, 50, 20, 10, 5, and 1 ppm for 1 h at each concentration until scale formation occurred. Two blanks tests with no inhibitor were also carried out in each run, before and at the end of the SI tests. In addition, we adjusted the pH of all SIs tests in this work in the range of pH 5-7 to keep the role of pH on the inhibition efficiency of the SIs constant and consistent with field conditions, as discussed previously.35 For the sulfate scale test, the FIC of the commercial products DTPMP and ATMP were 5 and 10 ppm respectively. However, for carbonate scale, the FICs for these SIs were 10 and 20 ppm respectively as presented in Table 3. For the protein inhibitors, meat peptone, gelatine peptone, crotein C, wheat, gluten, potato, soy and pea peptones, whey, and Nisaplin, a negligible or weak inhibition effect compared to blank tests was seen at 100 ppm for sulfate scale. For example, Meat Peptone N1 gave rapid scaling at 8 minutes at 100 ppm for both runs. For casein protein, the data indicate that the first and repeat tests gave slightly longer times to scale formation than the other proteins. Interestingly, Tryptone N1 19553 showed muchimproved sulfate and carbonate scale inhibition compared to a blank test and the other casein derivatives. The FIC was 20 ppm after 5 min for sulfate scale as shown in Figure 6 and 5 ppm for 8 min for carbonate scale. In addition, Figure 7 shows the FIC values of the commercial Casein Peptone Plus 19544 for sulfate scale. The FIC was 50 ppm for 22 min for each run compared to blank tests. We also found that Casein Peptone Plus 19544 gave good carbonate scale inhibition. The FIC was 20 ppm for 4 min for each run, as presented in Table 3 and Figure 6.

15


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Furthermore, it is interesting that all casein peptones and tryptones showed good compatibility with calcium ions (724ppm) under the scale inhibition test conditions. This was done by observing the metal ion tolerance toward SIs before scale formation on the graph of differential pressure. For example, Figures 8 and 9 showed no build-up of pressure that is not due to scale formation for tryptone N1 19553 for both runs for sulfate and carbonate scaling. Some phosphate inhibitors can be poorly intolerant of calcium ions and show a gradual build-up of calciuminhibitor deposit, so here we presume the other hydrophilic groups in the casein help keep the peptones soluble. To determine the limits of the window of calcium compatibility a series of bottle tests at 60oC was carried out for Casein Peptone N1 19516 and the Tryptone N1 19553. It was found that there was no clouding or precipitation in any test for up to 50000ppm (5 wt.%) chemical and 20000ppm Ca2+ ions. This means these scale inhibitors are compatible with very high calcium concentrations, both for topside injection or for squeezing into low formation temperature reservoirs.

Table 2. Sulfate scale tests showing FIC values with commercial and proteins SIs. Inhibitor

First blank

First scale test Concn. Time (ppm) (mins) 5 9

Second scale test Concn. (ppm) 5

Second blank Time (mins) 11

Time (mins) 7

DTPMP

Time (mins) 5

ATMP

4

10

13

10

16

6

4

50

22

50

22

7

4

50

18

50

18

7

Casein

Peptone

Plus

19544 (Mw= 491 Da ) Casein

Peptone

N1

16


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Energy & Fuels

19516 (Mw= 681 D ) Casein Peptone E1

3

50

15

50

15

5

19553

3

20

5

20

5

7

Tryptone Plus AI343

5

50

21

50

21

7

Caseinate

4

50

15

50

15

6

Nisaplin (Mw = 3354

5

100

8

100

8

7

Whey protein-80%

6

100

24

100

24

8

MeatPeptone N1 19521

5

100

8

100

8

7

Crotein C

4

100

9

100

9

5

Gelatine Peptone N2

8

100

10

100

10

9

5

100

8

100

8

7

7

100

19

100

19

8

19546 (Mw= 840 D ) Tryptone

N1

(Mw= 490 D )

(Mw= 600 D ) Sodium (P5206-1)

D)

(Mw= 1040 D)

19532 (Mw= 1111 D) Plant Peptone E1 19025 (Mw= 400 D) Pea Peptone A482 AI275 (Mw= 550 D)

17


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Soy Peptone A3 SC

Page 18 of 29

6

100

10

100

10

7

5

100

24

100

24

7

Gluten from Wheat

7

100

55

100

55

8

SI-1

5

100

10

100

10

6

SI-2

7

20

8

20

8

8

SI-3

6

50

50

50

50

7

SI-4

5

20

5

20

7

7

Casein Peptone Plus

7

100

30

100

29

8

19685 (Mw= 227 D) Wheat Peptone E430 AI233 (Mw= 350 D)

19544 (Mw= 491 D )b a

D= Daltons the Casein Peptone Plus 19544 was tested for sulfate scale after thermal ageing at 100oC for one week under anaerobic conditions.

b

Table 3. Carbonate scale tests showing FIC values with commercial and proteins SIs. Inhibitor

First blank

First scale test Concn. Time (ppm) (mins) 10 20

Second scale test Concn. (ppm) 10

Second blank Time (mins) 20

Time (mins) 9

DTPMP

Time (mins) 7

ATMP

7

20

26

20

26

9

8

20

4

20

4

7

Casein

Peptone

Plus

19544 (Mw= 491 D)

18


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Energy & Fuels

Casein

Peptone

N1

6

5

7

5

7

7

7

20

23

20

23

8

8

5

8

5

8

9

10

10

8

10

8

10

9

50

46

50

46

8

SI-2

8

10

9

10

9

7

SI-3

8

10

25

10

25

8

SI-4

9

10

10

10

10

8

19516 (Mw= 681 D ) Casein Peptone E1 19546 (Mw= 840 D ) Tryptone N1 19553 (Mw= 490 D ) Tryptone Plus AI343 (Mw= 600 D ) Sodium

Caseinate

(P5206-1)

19


Page 20 of 29

120

FIC (SO4)

100

FIC (CO3)

80 60 40 20 0

Scale Inhibitors (SIs)

Figure 6. FIC results for casein and tryptone proteins, modified casein pepetone and commercial

1600

14

1400

12

1200

10

1000 8

100 ppm

50 ppm

100 ppm

800

50 ppm 6

600 4

400

2

200 0

0 0

20

40

60

80

100

120

140

160

180

200

Time (min) abs tdx1

abs tdx2

20


diff 1

220

240

Differential pressure (psi)

SIs for sulfate and carbonate scales.

Absolute pressure (psi)

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

Fail inhibitor concentration (FIC)

Energy & Fuels

Page 21 of 29

Figure 7. FIC and time values from high-pressure dynamic tube blocking experiments of Casein

1600

14

1400

12

1200

10

1000 50 ppm

100 ppm

800

20 ppm

50 ppm

8

20 ppm

6 600 4

400

2

200


Peptone Plus 19544 for sulfate scale.


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Figure 9. FIC and time values from high-pressure dynamic tube blocking experiments of tryptone N1 19553 for carbonate scale.

All casein peptones and tryptones are manufactured by a controlled enzymatic hydrolysis of casein. The above interesting results of nature casein proteins as a good SIs encouraged us to modify the amino groups of the polymer by phosphonation, sulfonation and/or reaction with anhydride derivatives. For the modification of proteins, we chose to use Casein Peptone 19544 based on the relatively high percentage of lysine (and therefore derivatizable amino groups) in the polymer. Phosphonation of amino groups of Casein Peptone Plus 1954 was attempted by the aid of Moedritzer-Irani reaction to give SI-1 or by reaction with 3-chloropropyliminobis(methylene phosphonic acid) to produce SI-2. It was found that the SI-1 showed low sulfate scale inhibition 22


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compared to the unfunctionalized starting material, giving an FIC of 100 ppm after 10 min at the test conditions. A possible reason for the poor inhibition performance of SI-1 may be due to acid hydrolysis of proteins even as far as to the constituent amino acids. In contrast, the reaction product for making SI-2 at 70oC gave improved performance against both sulfate and carbonate scaling compared to the Casein Peptone Plus 1954. This might initially suggest that a target product SI-2 had indeed been formed but there was a second possibility: the 3-chloro propyl imino bis(methylene phosphonic acid) may some effect as a SI in its own right and could improve the performance of the casein, acting as a synergist. To test this we conducted the synthesis of SI-2 at room temperature, which should not lead to any appreciable reaction, but rather a simple mixing of the two starting materials. This mixture gave a very similar performance as the heated mixture on both sulfate and carbonate scales, which indicated that it is plausible that no reaction had taken place. A reaction may have been more likely with the more activated 3-bromo propyl imino bis(methylene phosphonic acid) but this is not commercially available. We also investigated the possibility to sulfonate the amine groups of Casein Peptone Plus 19544 by treatment with formaldehyde-sodium bisulfite adduct to give SI-3. The product obtained showed only moderate calcium carbonate and barium sulfate scale inhibition compared to the starting material as tabulated in Tables 2 and 3. A fourth reaction of the peptone that we attempted was to add extra carboxylate groups by a ring-opening reaction of amine or hydroxyl groups with maleic anhydride to give SI-4. This time, carbonate and sulfate scale inhibition performance increased whether the reaction with maleic anhydride was carried out at room 23


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temperature or 70oC. For sulfate scale, the FIC was 20 ppm for 5 minutes for each run as presented in Table 2 and Figure 10. As with the reaction with 3-chloro propyl imino bis(methylene phosphonic acid), we cannot be sure if maleic anhydride has indeed reacted with the peptone. NMR spectroscopic analysis was inconclusive. Secondly, the improvement in performance could either be due to a reaction having taken place or a synergistic effect of the

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peptone and maleic acid from aqueous hydrolysis.


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To investigate the possibility to use the casein peptone for squeeze treatments, in which good and long-term thermal stability is needed, we carried out hydrothermal stability tests. The conditions chosen were not too severe; a 5 wt.% solution of Casein Peptone Plus 19544 was heated in a sealed tube at 100 oC for one week under anaerobic conditions. After ageing the Casein Peptone Plus 19544 was retested and showed to give significantly poorer sulfate scale inhibition. The FIC was now found to be 100 ppm after 10 min for each run, as shown in Figure 11. This result indicated considerable if not complete breakdown of the protein and that squeeze treatments at 100oC or more are very unlikely to succeed. Thus, the best proteins natural are more useful for topside continual injection applications where the temperature and residence time are within the

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Figure 11. Fail inhibitor concentration (FIC) and time values from high-pressure dynamic tube blocking experiments of Casein Peptone Plus 19544 after ageing at 100oC for sulfate scale.

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4. CONCLUSION

In this study, we have evaluated the calcium carbonate and barium sulfate inhibition performance of a series of commercial proteins from sources such as milk, meat, gluten, soya and pea using a classic dynamic tube blocking equipment at approximately 80 bars and 100oC. The fail inhibitor concentration (FIC) for protection against scale has been determined and comparison has been made with some commercial scale inhibitors. It was found that all proteins belonged to meat, gluten, soya and pea showed low calcium carbonate and barium sulfate scale inhibition compared to the milk proteins and commercial products, ATMP and DTPMP. For example, Casein Peptone Plus 19544, Casein Peptone N1 19516 and Tryptone N1 19553 gave the best SI performance for sulfate scale inhibition. Interestingly, Casein Peptone N1 19516 and Tryptone N1 19553 showed improved carbonate scale inhibition compared to the commercial SIs. The FIC for Casein Peptone N1 19516 was 5 ppm for 8 minutes for each run. The peptones also showed improved calcium compatibility. However, thermal ageing studies indicated that the best proteins were not stable for squeeze treatments at 100oC and therefore are best used for topside continual injection. Attempts were also made to functionalize the side chains of Casein Peptone Plus 19544 to incorporate more carboxylate groups, or the first phosphonate or sulfonate groups, to improve the SI performance. The scale inhibition performance of the modified peptone did increase on two occasions compared to the starting peptone, but it was inconclusive whether this was synergy of unreacted reagent or a genuine new product had formed. For example, the FIC for SI-4 was 20 ppm for 5 minutes for sulfate scale. We are currently investigating the use of 26


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biodegradable synergists with proteins to improve the scale inhibition performance, as well as other modifications of Casein Peptone N1 19516 by a variety of chemical reactions.

ACKNOWLEDGMENTS We gratefully acknowledge Total E&P Norge AS for financial support.

REFERENCES (1) Kelland, M. A. Production Chemicals for the Oil and Gas Industry; Second Edition, CRC Press (Taylor & Francis Group): Boca Raton, FL, 2014. (2) Frenier, W.W.; Ziauddin, M. Formation, Removal and Inhibition of Inorganic Scale in the Oilfield Environment. SPE Publishing, Houston, U.S. 2008. (3) Amjad, Z. The Science and Technology of Industrial Water Treatment. CRC Press (Taylor & Francis Group): Boca Raton, FL, 2010. (4) Sallis, J. D.; Juckes, W.; Anderson, M. E. In Mineral Scale Formation and Inhibition; Amjad, Z., Ed.; Plenum Press: New York, 1995. (5) Tomson, M.B.; Fu, G.; Watson, M.A.; Kan, A.T. SPE Prod. Facil. 2003, 18, 192. (6) Stewart, N.J.; Walker, P.A.M. US Patent 6527983, 2003.

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(7) Sorbie, K.S.; Laing, N. How Scale Inhibitors Work: Mechanisms of Selected Barium Sulfate Scale inhibitors Across a Wide Temperature Range, SPE 87470, SPE International Symposium on Oilfield Scale, 26-27 May, Aberdeen, UK, 2004. (8) Li, J.L.; Liu, X.; Lai, D.M.; Wang, H.Y.; Ji, Y.Y. Oilfield Chem. 2013, 30, 438. (9) Touir, R.; Dkhireche, N.; Touhami, M.E.; Sfaira, M.; Senhaji, O.; Robin,J.J.; Boutevin, B.; Cherkaoui, M.; Mater. Chem. Phys. 2010, 122, 1. (10) Wang, C.; Li, S.P.; Li, T.D. Desalination 2009, 249, 1. (11) Mei, P.; Xiao, J.X. Ind. Water Treat. 2005, 25, 36. (12) Yang, Q.F.; Gu, A.Z.; Ding, J.; Shen, Z.Q. Chin. J. Chem. Eng. 2002, 10, 190. (13) Mishra, S.; Saxena, P.; Deore, D.A. Polym.-Plast. Technol. 2005, 44, 1389. (14) Shen, Z.H.; Li, J.S.; Xu, K.; Ding, L.L.; Ren, H.Q.; Desalination 2012, 284, 238. (15) Mady, M.F.; Bagi, A.; Kelland, M.A. Energy Fuels 2016, 30, 9329. (16) Zeng, J.P.; Wang, F.H.; Zhou, C.; Gong, X.D. Chin. J. Chem. Phys. 2012, 25, 219. (17) Touir, R.; Dkhireche, N.; Touhami, M.E.; Lakhrissi, M.; Lakhrissi, B.; Sfaira, M. Desalination 2009, 249, 922. (18) Zhang,Y.; Yin, H.; Zhang, Q.; Li,Y.; Yao, P. Desalination 2016, 395, 92. (19) Demadis, K.D.; Preari, M. Desalin. Water Treat. 2015, 55, 749. (20) OSPAR Guidelines for Completing the Harmoniised Offshore Chemical Notification Format (2010-05) (http://www.ospar.org). (21) Gupta, A.K.; Berry, C.; Gupta, M.; Curtis, A.; IEEE Trans. Nanobiosci. 2003, 2, 255. (22) Laurent, S.; Forge, D.; Port, M.; Roch, A.; Robic, C.; Elst, L.V.; Muller, R.N.; Chem. Rev. 2008, 108, 2064. 28


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(23) Sahu, A.; Kasoju, N.; Bora, U. Biomacromolecules, 2008, 9, 2905. (24) Huppertz,T.; Smiddy, M.A.; DeKruiff, C.G. Biomacromolecules, 2007, 8, 1300. (25) DeKruiff, C.G.; Huppertz, T.; Urban, V.S.; Petukhov, A.V. Adv. Colloid Interface Sci. 2012, 36, 171. (26) Semo, E.; Kesselman, E.; Danino, D.; Livney, Y.D. Food Hydrocolloids 2007, 21, 936. (27) Pan, X.Y.; Yao, P. and Jiang, M. J. Colloid Interface Sci. 2007, 315, 456. (28) Perfeldt, C.M.; Chua, P.C.; Daraboina, N.; Friis, D.; Kristiansen, E.; Ramlov, H.; Woodley, J.M.; Kelland, M.A.; von Solms, N. Energy Fuels 2014, 28, 3666. (29) Moedritzer, K.; Irani, R. R. J. Org. Chem. 1966, 31, 1603. (30) Hudson, H.R.; Koroma, S.N.; Ojo, Isaac, A. O. Phosphorus Sulfur Silicon Relat. Elem. 2015, 190, 2187. (31) Bodnar, S.H.; Fisher, H.C.; Miles, A.F.; Sitz, C.D.; International Patent Application WO/2010/002738. (32) Jensen, M. K.; Kelland, M. A. J. Pet. Sci. Eng. 2012, 66, 94. (33) George, A.; Veis, A. Chem. Rev. 2008, 108, 4670. (34) Liu, Yan.; Cui, Y.; Mao, H.; Guo, R. Cryst. Growth Des. 2012, 12, 4720. (35) Amjad, Z. Water Treat. 1994, 9, 47.

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Study on Various Readily Available Proteins as New Green Scale

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