Calcium Chloride Calcium Bromide Zinc Bromide Solutions

CaCl2/CaBr2/ZnBr2 solutions using 15.0 ppg (1.80 SG) CaCl2/CaBr2 brine and 19.2 ppg (2.28 SG) CaBr2ZnBr2, the proper order of addition is as follows:

  1. Start with the 15.0 ppg (1.80 SG) CaCl2/CaBr2 brine.
  2. Add the 19.2 ppg (2.28 SG). CaBr/ZnBr2 brine.

Rules of thumb for blending of brines

  1. DO NOT CUT SACKS. Exception: CaBr2 brines from 11.6 to 15.1 ppg.
  2. An increase of CaBr2 decreases the crystallization temperature for CaBr2 brines.
  3. An increase of ZnBr2 decreases the crystallization temperature in any blend.
  4. A decrease in crystallization temperature increases the cost of the fluid.
  5. Do not mix fluids containing divalent ions (Ca2+, Zn2+) with fluids containing monovalent ions (Na+, K+), Precipitation may occur.
  6. Do not increase the pH of CaBr2 or ZnBr2 fluids or precipitation may occur.
  7. Do not add large volumes of water to CaBr2 or ZnBr2 brines or precipitation may occur.

Fluid Selection A good approach to selecting a fluid is to decide what functions the fluid is to perform and then select a base fluid and additives that will most effectively do the job. The first decision in selecting a fluid is identification of the required functions or properties. The next step is the selection of the type of fluid to be used. The properties or functions of the fluid dictate the type of fluid to be used. If the decision is made in reverse order, a poor performance is likely to result.

Completion and Workover Fluids Weighting Materials

Calcium Carbonate Calcium carbonate is available in five grades: 5,50, 150, 600, and 2,300. At least 50% of the particles in each grade are large than the size (^m) indicated by the number. Other grind sizes can be made available.

Typical Physical Constants

Hardness (Mohr's scale) 3

Specific gravity 2.7

Bulk density, lb/ft3, or ppg 168.3 or 22.5

Typical Chemical Composition

CaCO3 (5) (93% will pass through a 325 mesh) can be used alone or with (FeCO3) to increase the densities of freshwater or brine fluids beyond their saturation limits. It may also be used to increase the density of oil base fluids (Table 1.10).

CaCO3 (5) can be used instead of clays to provide wall cake buildup for acid-soluble fluids.

Total carbonates (Ca2+, Mg2+)

Total impurities (AI2O3, Fe2O3, SiO2, Mn)

TABLE 1.10 Specific Gravity and Specific Weight of Common Materials

Material

Specific gravity

lb/gal

lb/bbl

Barite

4.2-4.3

35.0-35.8

1470-1504

Calcium carbonate

2.7

22.5

945

Cement

3.1-3.2

25.8-26.7

1085-1120

Clays and/or

2.4-2.7

20.0-22.5

840-945

drilleld solids

Diesel oil

0.84

7.0

294

Dolomite

2.8-3.0

23.3-25.0

980-1050

Feldspar

2.4-2.7

20.0-22.5

840-945

Fresh water

1.0

8.33

350

Galena

6.5

54.1

2275

Gypsum

2.3

19.2

805

Halite (rock salt)

2.2

18.3

770

Iron

7.8

65.0

2730

Iron oxide

5.1

42.5

1785

(hematite)

Lead

11.4

95.0

3990

Limestone

2.7-2.9

22.5-24.2

945-1015

Slate

2.7-2.8

22.5-23.3

945-980

Steel

7.0-8.0

58.3-66.6

2450-2800

It may also be used as an acid-soluble bridging agent for formations having pore sizes up to 15 ^m.

CaCO3 50,150,600, and 2,300 grades are recommended for use as bridging agents for lost circulation problems, in squeeze mixtures, and in other similar applications. The particle size distribution is maintained in the slurry to provide effective bridging at the surface of the pay zone.

Acid solubility CaCO3 is 98% soluble in 15% HCl solution. One gallon of 15% HCl dissolves 0.83 kg or 1.84 lb of CaCO3.

Bridging agent Normal treatment is 2.27 to 5 kg (5 to 10 ppb) of the appropriate grade(s). From 5% to 10% of the material added should have particle size at least one third of the formation pore diameter.

Iron Carbonate Iron carbonate is used to achieve densities in excess of 14.0 ppg in (1.68 SG) solids-laden systems. The maximum density of a CaCO3 fluid is approximately 14.0 ppg (1.68 SG) and the maximum density of iron carbonate fluids is 17.5-18.0 ppg (2.10-2.16 SG). For weighting fluids in the 13.0-16.5 ppg (1.56-1.98 SG) range, a blend is recommended.

The following precautions should be considered when using iron carbonate:

  1. Iron carbonate is only 87% acid soluble, and after acidizing, 13% of the solids added may be left to plug the formation or may be flushed out, depending on the size and distribution of the formation flow channels.
  2. Mud acid, a combination of hydrofluoric acid and hydrochloric acid, should not be used with iron carbonate. The hydrofluoric acid reacts with iron carbonate to produce insoluble salts of acidic and basic nature (iron fluoride and iron hydroxide). When using iron carbonate, use only hydrochloric acid.
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  • Patrick
    How to increase calcium bromide solution?
    5 months ago

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