Soluble Silicates - ACS Publications - American Chemical Society

12 S o d i u m Silicate i n C h e m i c a l F l o o d i n g Processes

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for Recovery of C r u d e O i l s PAUL H. KRUMRINE The PQ Corporation, Research and Development Center, Lafayette Hill, PA 19444 Sodium silicates have found numerous applications in the oil industry, particularly in EOR chemical processes. The objective of this paper is to review these applications and relate them to the basic properties and reactions of sodium silicate, in order to develop a better understanding of how silicates are used to solve a number of interesting problems in oil recovery. The silicate anion, in all its many forms, has specific properties which make it a valuable component in the various enhanced recovery processes. Among these properties are its ability: to sequester multi-valent metal cations; to act as a sacrificial agent in the adsorption process by clays; to maintain water-wettability; to reduce permeability in high permeability areas to improve sweep; and to aid in reducing IFT at the oil/water interface. Each of these properties depends on the size, charge, and basicity of the silicate molecule, which can be varied by changing ratio and concentration. Alkaline chemicals have been suggested as an agent to improve oil recovery as early as 1917 by Squires (1). Several others such as Atkinson (2), Nutting (3). Beckstrom and Van Tuyl (4), Subkow^iL', Reisburg and Dosher\â».Z/, and Wagner and Leach (8) have described the various mechanisms of displacement and benefits from injecting these chemicals. Nutting in 1925 was the first to suggest that sodium silicate might be used to improve waterfloods. Over the years, several field trials have been reported using caustic with limited success (3, 9-13). More recently four alkaline field trials have been .started, employing specifically sodium orthosilicates. These include projects by THUMS at the Wilmington field, by Aminoil USA at the Huntington Beach Field and by Union in their Van and Orcutt Fields. 0097-6156/82/0194-0187$07.75/0 © 1982 American Chemical Society In Soluble Silicates; Falcone, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

SOLUBLE


188

SILICATES

Work by Holm (JA, 15) has e s t a b l i s h e d the b e n e f i t of using a l k a l i n e chemicals as a p r e f l u s h agent for micellar/polymer f l o o d s . A f i e l d t r i a l of t h i s process using an o r t h o s i l i c a t e p r e f l u s h has been c a r r i e d out at Gary Energy's B e l l Creek F i e l d (16). A d d i t i o n a l o i l has been recovered, however, i t i s d i f f i c u l t to assess how much of t h i s was due to the p r e f l u s h . Recently we have c a r r i e d out l a b o r a t o r y t e s t s (17, 18, 19) i n which the sodium s i l i c a t e was added d i r e c t l y to a d i l u t e surfactant s o l u t i o n to recover o i l . Such a process would be akin to a l k a l i n e f l o o d i n g processes where a d i l u t e s u r f a c t a n t i s formed i n - s i t u . In t h i s case however the crude i s l i g h t e r and does not contain the n a t u r a l acids necessary to form surfactants i n - s i t u . Therefore s u r f a c t a n t i s i n j e c t e d and protected or enhanced by the sodium s i l i c a t e such that a low tension waterflood i s assured. Such a system i s l e s s complex and therefore more widely a p p l i c a b l e than micellar/polymer techniques thus f i l l i n g the v o i d between the a l k a l i n e and micellar/polymer EOR processes. Other techniques such as the m o b i l i t y c o n t r o l l e d c a u s t i c f l o o d i n g process by Saram (20, 21, 22) and combinations of polymer and a l k a l i have been i n v e s t i g a t e d , but these have not been widely used as yet and are c u r r e n t l y perceived as extensions of the three processes discussed above. SILICATES IN ALKALINE FLOODING Sodium o r t h o s i l i c a t e a l k a l i n e f l o o d i n g i s one of the most promising EOR technologies now under development. The THUMS and Aminoil USA o r t h o s i l i c a t e a l k a l i n e floods have received a good deal of p u b l i c i t y due to DOE p a r t i c i p a t i o n i n these p r o j e c t s , and t h e r e f o r e the parameters o f these floods are w e l l known, and shown i n Table I. Reservoir c o n d i t i o n s f o r these two floods are q u i t e d i f f e r e n t as are the flood designs, however t h e i r c h a r a c t e r i s t i c s are i l l u s t r a t i v e o f the type o f r e s e r v o i r which i s conducive to a l k a l i n e f l o o d i n g . Both r e s e r v o i r s have high concentrations of d i v a l e n t metal c a t i o n s contained i n the connate water, and the o i l i n each r e s e r v o i r i s a h e a v i e r , more viscous crude c o n t a i n i n g some n a t u r a l a c i d s ; t h e r e f o r e , both e l e c t e d to use sodium o r t h o s i l i c a t e instead o f sodium hydroxide alone. The p r e d i c t e d b e n e f i t i n increased o i l production i n the two r e s e r v o i r s i s shown i n the core f l o o d r e s u l t s of Tables I I (23) and I I I (24). In each comparison the sodium o r t h o s i l i c a t e was found to give an a d d i t i o n a l 20 to 50% more o i l than the sodium hydroxide. Since the pH and a l k a l i values of the two chemicals are n e a r l y i d e n t i c a l , the d i f f e r e n c e i n performance i s a t t r i b u t e d to the s i l i c a moiety o f the o r t h o s i l i c a t e , and predominantly i t s i n t e r a c t i o n with the hardness ions. A l s o , other more subtle a f f e c t s w i l l be discussed.

In Soluble Silicates; Falcone, J.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.


12.

KRUMRiNE

Sodium Silicate in Chemical Flooding Processes

189

TABLE I RESERVOIR PARAMETERS

Type o f Reservoir Rock

AMINO IL Unconsolidated Sand

Average P o r o s i t y Average O i l G r a v i t y Average P e r m e a b i l i t y ( b r i n e ) Average Depth Average Net Sand Thickness Bottom Hole Temperature Average O i l V i s c o s i t y at Reservoir Temperature A c i d Number P i l o t Area Volume - acre feet Tank O i l i n Place - M b b l Average Water/Oil R a t i o I n i t i a l Water S a t u r a t i o n (average) Residual O i l S a t u r a t i o n a f t e r Waterflooding

THUMS Unconsolidated Sand

0.24 23° 200 md 3750 260* 170°

0.26 19.6° 400 md 3000« 305» 125°

11 cp 0.65 64.7 ac 17,300 12,300 40/1 18%

23cp 2.5 93 ac 26,900 33,900 10/1 29%

35%

38%

f

Reproduced, with permission, from Ref. 24. Copyright 1979, Society of Petroleum Engineers of AIME.



190

SOLUBLE

SILICATES

TABLE I I INCREASED RECOVERY OF WILMINGTON FIELD RANGER ZONE CRUDE C-331 FROM PRESERVED CORES BY ALKAINE FLOODING

ALKALINE TEST NO. MATERIAL

CONC.PREFLUSH % PV WT.% (1% NaCl)

INCREASED RECOVERY % PV OVER WATERFLOOD AT PV INJECTED 1

5

10

39

NaOH

0.2

0.2

40

NaOH

0.2

0.2

2.5

41

NaOH

0.2

0.05

3.0

42

NaOH

0.2

0.05

1.5

43

Na Si0

4

0.2

0.05

3.0

5.8

7.8

44

Na Si0

4

0.2

0.05

2.7

4.8

7.9

4

4

Reproduced, with permission, from Ref. 24. Copyright 1979, Society of Petroleum Engineers of AIME.



PV, ml

Total

PV I n j .

PV A l k a l i n e I n j .

Cone., WT %

Alkali

RUN

4

237.8

3.3

0.5

0.15

Na SiO Η

Ι

1,000 μ -

10,000 ι—



100-300ppm

None

10-20ppm

0.376% N a C o

lOppm lOppm lOppm

0.376% N a 0 ( S i 0 2 ) 3 . 2

0.426% N a 0 ( S i 0 ) 1 . 6

1.0% N a S i 0 4

4

lOppm

0.376% STPP

2

2

2

lOppm

3

0.376% Na P04

2

20ppm

0.376% NaOH

3

Hardness

Alkaline Additive

0.68g 0.65g 0.26g 0.28g 0.18g 0.15g 0.20g 0.25g

15.5% 65% 64% 75% 80% 72.5% 65.8%

Surfactant Retention/ kg B e r e a

15%

Surfactant Recovery

ALKALI EFFECTS ON SURFACTANT RETENTION IN BEREA SANDSTONE

TABLE V S


74%

68%

20%

100%

95%

98%

90%

Alkali Recovery


206

SOLUBLE

SILICATES

can help to maintain the negative charge on these surfaces as shown i n Table V I I . Charges on m i n u s i l (very f i n e quartz) and montmorillonite c l a y p a r t i c l e s were measured i n a v a r i e t y o f a l k a l i n e and s u r f a c t a n t s o l u t i o n s . The surface charge i n these s o l u t i o n s as measured by e l e c t r o p h o r e t i c m o b i l i t y was found to become more negative i n the presence o f the s i l i c a t e i o n s . I f s u r f a c t a n t , i n o r g a n i c p r e c i p i t a t e s , or other chemical species are being r e t a i n e d i n the c o r e s , then the pores may begin to become blocked or decrease i n average diameter. This can a f f e c t flow patterns and the m o b i l i t y of the v a r i o u s phases w i t h i n that network. Severe plugging or r e d u c t i o n i n p e r m e a b i l i t y i s harmful due to l o s t i n j e c t i v i t y , while s e l e c t i v e p e r m e a b i l i t y r e d u c t i o n may be quite u s e f u l i n d i v e r t i n g f l u i d s i n t o p r e v i o u s l y unswept areas. Several t e s t s on l a r g e Berea slabs which can simulate an a r e a l p a t t e r n r a t h e r than a l i n e a r d r i v e have shown that the areas swept by s i l i c a t e enhanced s u r f a c t a n t f l o o d s are l a r g e r than simple s u r f a c t a n t LTWF processes. A v i s u a l comparison o f the swept areas i n two examples i s shown i n Figures 6 & 7. In Figure 6 no s i l i c a t e was used. A l a r g e slug of the d i l u t e s u r f a c t a n t s o l u t i o n was i n j e c t e d i n t o the lower l e f t - h a n d corner of the slab and produced from the upper right-hand corner. A f t e r about 3 PV o f i n j e c t i o n only about 26% of the r e s i d u a l o i l had been recovered whereas a l i n e a r f l o o d using the same s o l u t i o n recovered about 37%. Upon l a t e r v i s u a l i n s p e c t i o n of the c r o s s - s e c t i o n e d core i t appeared that only about 65% of the core area had been swept by the flood s o l u t i o n s . A s i m i l a r t e s t where a high r a t i o sodium s i l i c a t e was added showed that recovery o f r e s i d u a l o i l was about 46% as compared to 49% i n a l i n e a r f l o o d t e s t . This was v e r i f i e d b;, the c r o s s - s e c t i o n e d core diagrammed i n Figure 7 which showed that n e a r l y 91% o f i t had been swept. O v e r a l l p e r m e a b i l i t y r e d u c t i o n was only about 20%. Another set of core f l o o d i n g experiments showed how the a d d i t i o n of sodium s i l i c a t e can help to improve the sweep and recovery i n multipermeable zones. Two cores of d i f f e r e n t p e r m e a b i l i t y were i n d i v i d u a l l y prepared and then connected i n p a r a l l e l through a "T" type connection with the e f f l u e n t s c o l l e c t e d s e p a r a t e l y . The composite recovery curves f o r these t e s t s are shown i n F i g u r e 8. I n i t i a l production occurred from the higher p e r m e a b i l i t y s e c t i o n . At the point where each curve diverges i n t o two curves i s the beginning of production c o n t r i b u t i o n from the lower p e r m e a b i l i t y s e c t i o n . These t e s t s showed that the use o f a high r a t i o sodium s i l i c a t e r e s u l t s i n e a r l i e r production as w e l l as more production from the lower p e r m e a b i l i t y s e c t i o n . When the e f f l u e n t flow r a t i o s between the two p e r m e a b i l i t y zones were compared, i t was found that i n i t i a l l y the major p o r t i o n of the f l u i d i s d i v e r t e d i n t o the high p e r m e a b i l i t y zone. Then, g r a d u a l l y , t h i s zone i s s e l e c t i v e l y reduced i n p e r m e a b i l i t y so that more f l u i d i s



—

—

1.0

1.0

0.25

0.25

0.25

1.0

1.0

1.0

--

2

3

2

2

2

0.37 N a 0 ( S i 0 ) 3 . 2 2

2

0.37 N a C 0

0.37 NaOH

2

0.37 N a 0 ( S i 0 ) 3 . 2 2

2

0.37 N a 0 ( S i 0 ) 3 . 2 2

2

0.37 N a C 0 3

ALKALI

0.37 NaOH

* p l u s 10 ppm Ca + Mg i o n s

0.25

1.0

—

—

1.0

-

—

PETROLEUM SULFONATE

1.0*

1.0

NaCl

(%)

H

10.80

11.0

13.0

7.34

10.99

10.86

11.06

12.97

5.85

5.95

P

2.05

2.18

3.11

1.57

0.21

2.03

2.24

3.09

1.53

1.53

CONDUCTIVITY (m mho/r»)

-2.75

-2.25

-2.60

-2.10

-4.40

-2.75

-1.70

-1.90

MINUSIL

-3.75

-3.75

-2.50

-3.00

-2.50

-2.80

-2.90

-2.40

-2.40

-2.40

MONTMORILLONITE

ELECTROPHORETIC MOBILITY (urn cm/volt sec)

ELECTROPHORETIC MOBILITY OF TYPICAL RESERVOIR MINERALS VS. VARIOUS ALDALINE SOLUTIONS

SOLUTION COMPOSITION

TABLE V I I .


208

SILICATES


SOLUBLE

Figure 6. produced,

Radial flood using low tension water-flood system without silicate. (Rewith permission, from Ref. 18. Copyright 1981, Society of Petroleum Engineers of AIME.)


12.

Sodium

KRUMRiNE

Silicate

in Chemical

Flooding

Processes

209

1/4 PV (0.1% NaCl) PREFLUSH 5-SPOT

PATTERN

PROD.

4

9

CONTINUOUS (0.25% PETROSTEP 450, 1.0% NaCl, 0.3676 SODIUM SILICATE)

7


2

5

8

3 1

6

INJ.

A CROSS SECTIONS

0//

TOP

ψ,

BOTTOM PROJECTIONS

Figure 7. Radial flood using low tension water-flood system plus sodium silicate. (Reproduced, with permission, from Ref. 1 8 . Copyright 1981, Society of Petroleum Engineers of AIME.)



210

SOLUBLE

60.0

L

SILICATES

COMPOSITE CORES

50.0

10.0

30.0

20.0

10.0

0.25Z PETROSTEP

0.0 1.0

2.0

3.0

150, 1 . 0 Z NACL

4.0

5.0

PORE VOLUMES Figure 8. Recovery profiles from multipermeable zone floods. Key: , no alkali; ~—, 0.01% NaOH; , 0.367% Na CO ; and · ·. ·, 0.367% sodium silicate. (Reproduced, with permission, from Ref. 18. Copyright 1981, Society of Petroleum Engineers of AIME.) 2

s



12.

KRUMRINE

Sodium

Silicate

in Chemical

Flooding

Processes

211

d i v e r t e d i n t o the low p e r m e a b i l i t y zone, but only a f t e r the o i l has been recovered from the higher p e r m e a b i l i t y zone. Some o f t h i s m o b i l i t y c o n t r o l and improvement i n sweep could be due to the emulsions formed which e x h i b i t a higher bulk v i s c o s i t y . Some work by Wasan et a l (32) has shown that the sodium s i l i c a t e s w i l l r e s u l t i n emulsions with lower shear or i n t e r f a c i a l v i s c o s i t i e s than sodium hydroxide. These lower i n t e r f a c i a l v i s c o s i t i e s at the m i c r o - l e v e l help promote o i l coalescence so that o i l banking can occur and o i l d r o p l e t s are not retrapped and l e f t behind. The o i l banking and r a p i d e m u l s i f i c a t i o n on the macro-level or i n the bulk h e l p to g i v e good m o b i l i t y c o n t r o l . A l s o some recent work by Wasan^2JJ has i n d i c a t e d that the s i l i c a t e s tend to keep the surfaces more water-wet, thereby i n p r o v i n g recovery. I t has been noted that the t h i c k n e s s o f the water f i l m on quartz surfaces i s t h i c k e r when s i l i c a t e s are present. Further work i n these areas i s c u r r e n t l y being done to determine the l i m i t s and e f f e c t s on the o i l recovery mechanisms. CONCLUSIONS Sodium s i l i c a t e s can impart a number o f s i g n i f i c a n t b e n e f i t s i n chemical f l o o d i n g techniques. Among these b e n e f i t s are the following : s e q u e s t r a t i o n or r e d u c t i o n o f hardness maintenance o f negative surface charges on c l a y s and emulsion d r o p l e t s . improved coalescence o f o i l d r o p l e t s increased water-wetness reduced s u r f a c t a n t r e t e n t i o n reduced IFT and improved e m u l s i f i c a t i o n reduced a l k a l i consumption or r e a c t i o n — - improved sweep e f f i c i e n c y and m o b i l i t y c o n t r o l o v e r a l l improved recovery of r e s i d u a l crude o i l . The p r o p e r t i e s and b e n e f i t s a l l depend on the nature o f the s i l i c a t e molecules and t h e i r r e a c t i v i t y or a d s o r p t i v i t y which can be c o n t r o l l e d by adjustments i n the Si02/Na20 r a t i o and c o n c e n t r a t i o n . As these s i l i c a t e molecules are present i n a r e s e r v o i r environment over long periods o f time, the d i s t r i b u t i o n and c o n c e n t r a t i o n of species w i l l change due t o the many r e a c t i o n s which can occur. However, i t i s such s a c r i f i c i a l r e a c t i o n s o f the s i l i c a t e s which allow more o f the s u r f a c t a n t s , which are e i t h e r formed i n - s i t u or d e l i b e r a t e l y i n j e c t e d , to accomplish t h e i r intended r o l e o f m o b i l i z i n g and producing r e s i d u a l crude o i l .


212

SOLUBLE SILICATES

Acknowledgments The author would like to thank the PQ Corporation for granting me the permission to publish this paper. I would also like to thank the many people who have contributed to the knowledge and role of silicates in EOR processes and have shared this knowledge with me.


Literature Cited 1. 2. 3. 4. 5. 6. 7.

Squires F. U.S. Patent No. 1,238,355,(Aug. 28, 1917). Atkinson, A. U.S. Patent No. 1,651,311, (Nov. 29, 1927). Nutting, P.G. Ind. Engr. Chem. 1925, 17, 1035. Beckstrom, R.C.; Van Tuyl, F.M. Bull. AAPG 1927, 223. Subkow, P., U.S. Patent No. 2,288,857, (July 7, 1942). Reisburg, J. and Doscher, T.M. Prod. Monthly 1956, 43. Doscher, T.M.; Reisburg, J. Canadian Patent No. 639,050 (March 27, 1962). 8. Wagner, O.R.; Leach, R.O. Trans. AIME 1959, 216, 65. 9. Leach, R.O.; Wagner, O.R.; Wood, H.W.; Harpke, C.F. J. Pet. Tech. 1967, 206. 10. Emery, L.W.; Mungan, N.; Nicholson, R.W. J. Pet. Tech. 1970, 1569. 11. McAuliffe, C.D. J. Pet. Tech. 1973, 721. 12. Graue, D.J.; Johnson, C.E. J. Pet. Tech. 1974, 1353. 13. Raimondi, P.; Gallagher, B.J.; Bennett, G.S.; Ehrlich, R.; Messmer, J.H. J. Pet. Tech. 1977, 1359. 14. Holm, L.W.; Robertson, S.D. J. Pet. Tech. 1981, 161. 15. Holm, L.W. U.S. Patent No. 4,011,908, (March 15, 1977). 16. Goldburg, Α.; Stevens, P. "Proceedings of the 5th Annual DOE Symposium on EOR";The Petroleum Publishing Co.:Tulsa, OK,1979 p A-4/1. 17. Krumrine, P.H.; Campbell, T.C.; Falcone, J.S. SPE Preprint #8998, 1980. 18. Krumrine, P.H.; Falcone, J.S.; Campbell, T.C. SPE Preprint #9811,1981. 19. Krumrine, P.H.; Ailin-Pyzik, I.B.; Falcone, J.S.; Campbell, T.C."The Effect of Akaline Chemicals on the Adsorption of Anionic Surfactants by Clays", ACS Symposium on the Chemistry of EOR, March 1981. 20. Sarem, A.M. U.S.Patent No. 3,805,893, April 23, 1974. 21. Sarem, A.M. U.S. Patent No.3,876,002, April 8, 1975. 22. Sarem, A.M. SPE Preprint #4901, 1974. 23. Carmichael, J.D. "Improved Oil Recovery by Controlled Waterflooding, Caustic", DOE Progress Review No. 20, BETC-79/4, Quarter Ending Sept. 30, 1978, p. 28. 24. Campbell, T.C.,; Krumrine, P.H. SPE Preprint #8328, 1979. 25. Campbell, T.C. SPE Preprint #7873, 1979. 26. Whiteley, R.C.; Ware, J.W. J. Pet. Tech. 1977, 925.


12. KRUMRINE


27.

Sodium Silicate in Chemical Flooding Processes

Widmyer, R.H.; Satter, Α.; Frazier, G.D.; Graves, R.H. J.Pet. Tech. 1977, 933. 28. Talash, A.W.; Strange, L.K. SPE Preprint #10162, 1981. 29. Murphy, C.L.; Thiede, D.M.; Eskow, J.O. SPE Preprint #6005, 1976. 30. Somasundaran, P.; Hanna, H.S. SPE Preprint #7059, 1978. 31. Tsai, F.S.; and Falcone, J.S. "Influence of Sodium Silicates and Other Reagents on Zeta Potential of Oxide-Water Interfaces", ACS/CSJ Chem. Cong., Honolulu, HI, April 1979. 32. Wasan, D.T.; Sampath, K.; McNamara, J.; Perl, J . ; Aderange, N.; Shah, S. M.; Shah, R.; Chan, M.; Nevrekar, P.; Pasquarelli, C.; Srivatsa, S.; Venkataraman, K. "The Mechanism of Oil Bank Formation, Coalescence in Porous Media and Emulsion Stability", 4th Annual DOE Symposium, Tulsa, OK, Aug. 1978. 33. Chang, M.M.; Wasan, D.T. SPE Preprint #9001, 1980. RECEIVED March 8, 1982.


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Soluble Silicates - ACS Publications - American Chemical Society

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