LiLI L

salt diluted

Figure 4-30a. Effect of order of addition of salt and polymer (schematic)

Figure 4-30b. Platelets repel each other when the edges are saturated with poly electrolyte (schematic, plan view).

carry no electrostatic charge. Consequently, they have greater stability in high salinity fluids. Starch is nonionic, and as previously mentioned, is used for filtration control in salt water muds. It has the advantage of being inexpensive, but the disadvantage of being biodegradable, and a biocide must be used with it.

Other nonionic polymers include hydroxyethylcellulose (HEC) and guar gum. Like CMC, HEC is made from cellulose, but its functional group is an ethylene oxide chain, (CH2-0-CH2)n- HEC has two great advantages: it is stable in polyvalent brines, and it is almost completely soluble in acid. Consequently it is used a great deal in completion and workover fluids (see Chapter 10). Guar gum is also used in workover fluids, but is degraded by enzymes instead of acid. The colloidal activity of natural gums is reduced by high concentrations of monovalent salts, and eliminated in polyvalent brines. However, gums that have been reacted with ethylene oxide or propylene oxide (see Figure 4-31) are stable even in saturated polyvalent brines.

Compared to clay muds, polymer suspensions have low yield points relative to plastic viscosity, and no real gel strength. Structural properties may be obtained, however, with a gum known as xanthan biopolymer (because it is produced by bacterial action) by crosslinking between the chains with chromic chloride. The structure of xanthan gum is shown in Figure 11-10.

There are also cationic polymers which have positive sites along the chain, created by the dissociation of an inorganic anion. They are used in drilling fluids mostly as emulsifiers and wetting agents, as discussed in Chapter 7. However, a proprietary polyamine has recently been introduced for the purpose of stabilizing formation clays during completion and workover operations.58 The cationic group is strongly adsorbed on the clay, reducing its negative charge, and thus inhibiting swelling and dispersion.

Thermal decomposition is a major factor limiting the use of organic polymers in drilling fluids. It may be compensated for by the addition of fresh polymer, but the rate of decomposition increases with temperature, and above a certain temperature becomes excessive. Thomas59 developed a method, based on reaction rate kinetics, for determining the rate of decomposition at various temperatures. By this means he showed that the rate of decomposition of starch-based polymers increased sharply above about 225°F (107°C) and that of cellulose polymers above about 300°F (149°C), making their use uneconomical above those temperatures. He states that the method is applicable to other materials

CHiO(R)nH

CH20(R)nH

CHiO(R)nH

CH20(R)nH

R = CHjCHiO

Figure 4-31. Hydroxyalkyl guar gum molecule. (Courtesy of Stein Hall Company.)

R = CHjCHiO

Figure 4-31. Hydroxyalkyl guar gum molecule. (Courtesy of Stein Hall Company.)

References

1. Weaver. C.E., and Pollard, L.D., The Chemistry of Clay Minerals. Elsevier Scientific Publ. Co., New York, 1973.

2. Grim, R.E., Clay Mineralogy. McGraw Hill Book Co., New York, 1953.

3. Grim, R f . Applied Clay Mineralogy. McGraw Hill, 1962.

4. Marshall, C.E., The Colloid Chemistry of Silicate Minerals. Academic Press, New York, 1949.

5. Hofmann, U., Endell, K., and Wilm O. "Kristalstructur und Quellung von Motmorillonit," Z. Krist., vol. 86 (1933). pp. 340 348.

6. Marshall. C.E., "Layer Lattices and Base Exchange Clays," Z. Krist.. vol. 91 (1935). pp. 433 449.

X. Brindley, G.W. and Roy, R.,' 'Fourth Progress Report and First Annual Report." API Project 55 (Aug., 1957).

9. Weaver and Pollard, Chemistry of Clay Minerals, p. 63.

11. Dyal, R.S. and Hendricks, S.B., "Total Surface Areas of Clays on Polar Liquids as a Characteistic Index," Soil Sci. vol. 69 (June. 1950). pp. 421- 432.

12. Kyhn, A. "Studies in the Size and Shape of Clay Particles in Aqueous Suspension," Clays, day Minerals, vol. 6 (1957). pp. 220-235.

13. Might, R. Higdon, W.T., Darley, H.C.H., and Schmidt, P.W. "Small Angle Scattering from Montmorillonite Clay Suspension" J. Clwtn Phys. vol. 37 (Aug. 1962). pp. 502 510.

14. Melrose, J.C. Light Scattering Evidence for the Particle Size of Montmorillonite" Symp. Chemistry in Exploration and Production of Petroleum, ACS meeting Dallas. April 1956, pp. 19-29.

15. Barclay, L.M., and Thompson, D.W., "Electron Microscopy of Montmorillonite. " Nature, vol. 222 (1969). p. 263.

16. Bradley, W.F. "The Structure of Attapulgite," Mineralogist, vol. 25 (1940). pp. 405410.

17. Carney. L.L. and Meyer, R.L., "A New Approach to High Temperature Drilling Fluids," SPE Paper 6025. Annual meeting, New Orleans, Oct., 1976.

18. Jackson, M.L., "Frequency Distribution of Clay Minerals in Major Great Soil Groups as Related to Factors of Soil Formation," Clays Clay Minerals, vol 6 (1957). pp. 133 143.

19. Me A tee. J.L., "Heterogeneity in Montmorillonite." Clays. Clay Minerals, vol. ^ (1956). pp. 279-288.

20. Grim. Applied Clay Mineralogy, pp. 43 44.

21. Hendricks. SB. Nelson, R.A. and Alexander. L.T.. "Hydration Mechanism of the Clay Mineral Montmorillonite Saturated with Various Cations," ,/. Amer. ( hem. Sor.. vol. 62 (1940). pp. 1457- 1464.

22. Hendricks. S.B., and Jefferson, M.E., "Structure of Kaolin and Talc-Pyrophyllilc Hydrates and Their Bearing on Water Sorption of the Clays." Am. Mineralogist, vol. 23 (1938). p. 863-875.

23. Low, P.P., "Physical Chemistry of Clay-Water Interaction" Advan. Agron., vol. 13. (1961.) p. 323.

25. Ross, C.S. and Hendricks, S.B., "Minerals of the Montmorillonite Group " Professional Paper 205B, U.S. Dept. Interior, 1945, p. 53.

26. Norrish, K., "The Swelling of Montmorillonite,"' Disc. Faraday Soc. vol. 18, (! 954). pp. 120 134.

27. van Olphen, H., An Introduction to Clay ( <>Ibid Chemistry, second edition John Wiley & Sons, New York, 1977. p. 30.

28. Engelmann, W.H., Teriehow, O. and Selim, A.A., "Zeta Potential and Pendulum Sclerometer Studies of Granite in a Solution Environment. " U.S. Bar Mines, Report of Investigations 7048 (1967).

29. Schoßeid, R.K. & Samson, H.R., "Flocculation of Kaolinite Due to Oppositely Charged Crystal Faces." Disc. Faraday Sûç., vol. 18 (1954). pp. 135 145.

30. van Olphen, day Colloid Chemistry, p. 95.

31. Hauser, E.A. and Reed, C.E., "The Thixotropic Behavior and Structure of Bentonite," J. Phys. Chem., vol. 41 il937). pp. 910 934.

32. van Olphen, Clay Colloid Chemistry, p. 114.

33. Loomis, A.G., Ford, T.E. and Fidiam, J.F., "Colloid Chemistry ol Drilling Fluids," Trans. AIME, vol. 142 (1941). pp. 86-97.

34. van Olphen, Clay Colloid Chemistry, p. 114.

35. Jessen. F.W. and Johnson, C.A., "The Mechanism of Adsorption of Lignosulfonates on Clay Suspensions," Soc. Petrol. Eng. J. (Sept., 1963). pp 26" 273; Trans AIME, vol. 228.

36. McAtee, J.L. and Smith, N.R., "Ferrochrome Lignosulfonates

(1) X-Ray Adsorption Edge Fine Structure Spectroscopy;

(2) Interaction with Ion Exchange Resin and Clays,"

J. Colloid Interface Sei. vol. 29, No. 3 (March, 1969). pp 389 398.

37. Mering, J., "On the Hydration of Montmorillonite," Trans. Faraday Sot . vol. 42 B (1946). pp. 205-219.

38. Garrison, A.D. and ten Brink, K.C., "Some Phases of Chemical Control of Clav Suspensions," Trans. AIME, vol. 136 (1940). pp. 175 194.

39. Darley, H.C.H., "A Test for Degree of Dispersion in Drilling Muds." Tram AIME, vol. 210 (1957). pp. 93 96.

40. Williams, F.J.. Neznayko, M. and Weintritt, D.J., "The Effect of Exchangeable Bases on the Colloidal Properties of Bentonite," J. Phys. ( 7wn., vol. 57 f 1953). pp 6 10.

41. van Olphen, Clay Colloid Chemistry, pp. 103-105.

42. M'Ewen, M.B. and Pratt, M.I., "The Formation of a Structural Framework in Sols of Wyoming Bentonite," Trans. Faraday Soc., vol. 53 (April, 1957). pp. 535 547.

43. Leonard, R. A. and Low, P.P., "Effect of Gelation on the Properties of Water in Clay Systems," Clays, Clay Minerals, vol., 10 (1961). pp. 311 325.

44. Norrish, K. and Rausell-Colom, J.A., "Low-Angle X-Ray Diffraction Studies of the Swelling of Montmorillonite and Vermieulite," Clays. Clav Minerais, vol 10 (1961). pp. 123 149.

45 Borst, R.L. and Shell, F.J., "The Effect of Thinners on the Fabric of Clay Muds and Gels," J. Petrol. Technoi. (Oct., 1971). p. 1193 -1201. 4ii Norrish, K. and Rausell-Colom, J.A., "Effect of Freezing on the Swelling of Chi) Minerals," Clay Minerals Bull. No. 5 (1963) pp. 9 16.

47. Gray, G.R., Foster, J.L. and Chapman, T.S., "Control of Filtration Characteristics of Salt Water Muds," Trans AIM E, vol. 146 (1942). pp. I 17 125

48. Chatter|i. J., and Borchardt, J. K., "Application of Water-Soluble Polymers in the Oilfield," J. Petrol. Technol. (Nov., 1981). pp. 2042-2056.

49. Lauzon, R. V., "Water-Soluble Polymers for Drilling Fluids." Oil Gas J. (April 19, 1982). pp. 93-98.

50. Kaveler, H. H., "Improved Drilling Muds Containing Carboxymethylcelluhise," API Drill Pred. Prac. (1946). pp. 43-50.

51. Scanley. C. S., "Acrylic Polymers as Drilling Mud Additives,"1 World Oil (July, 1959). pp. 122-128.

52. Clarke, R. N., Scheuerman, R. F., Rath, H., and van Laar, H.. "Polyacrylamide-Potassium Chloride Mud For Drilling Water-Sensitive Shales," ./. Petrol. Techno!. (June, 1976). pp. 719-727. Trans. AIME, vol. 261.

53. Gallus. J P., "Method for Drilling with Clear Water," U.S. Patent No. 3,040,820 (June 26, 1962).

54. La Mer, V. K. and Healey, T. W., "The Role of Filtration in Investigating Floceu lation and Redispersion of Colloidal Suspensions," J. Phys. Chem. vol. 67 (1963) pp. 2417-2420.

55. Ruehrwein, R. A. and Ward, D. W., "Mechanism of Clay Aggregation by Polyelectrolytes," Soil Sei., vol. 73 (1952), pp. 485-492.

56. Park, A.. Scott. P. P., and Lummus, J L., "Maintaining Low Solids Drilling Flu ids." Oil and Gas J. (May 30, 1960). pp. 81-84.

57. Deily, F. H., Lindblom, P., Patton, J. T., and Holman, W. E., "New Biopolymer Low-solids Mud Speeds Drilling Operations," Oil Gas J. (June 26, 1967). pp. 6270.

58. Williams, L. H., and Underdown, D. R., "New Polymer Offers Effective, Permanent Clay Stabilization Treatment," J. Petrol. Technol. (July, 1981). pp. 1211-1217.

59. Thomas, D. C., "Thermal Stability of Starch- and Carboxymethyl Cellulose-Based

Polymers I'sed in Drilling Fluids," Soc. Petrol. Eng. J. (April, 1982). pp. 171-180.

0 0

Post a comment