Lime | Schlumberger

Lime

Source of calcium and alkalinity in both water- and oil-base drilling fluids

Lime is used as a source of calcium and alkalinity in both water- and oil-based drilling fluids. Lime, a widely available commercial chemical, is an economical source of calcium (Ca2+) and hydroxyl ions (OH).

Drilling fluid applications for lime include increasing pH, providing excess lime as an alkalinity buffer, flocculating bentonite muds, removing soluble carbonate (CO32–) ions, controlling corrosion, and activating fatty-acid, oil-based mud additives.

Lime is a strong base and will form high-pH (alkaline) solutions. See product handling information.

 
Typical Physical Properties
Typical Physical Properties Physical appearance White powder
Typical Physical Properties Specific gravity 2.2
Typical Physical Properties pH (1% solution) 12.4
Typical Physical Properties Solubility @ 20° C (68° F) 0.165 g/100 ml water
Typical Physical Properties Bulk density 2,210.5 kg/m3 (138 lb/ft3)

Applications

Lime is used as an economical source of calcium for flocculating bentonite slurries (spud mud) for improved hole cleaning. Since it is only slightly soluble in water, it is used to maintain an excess of insoluble Lime in a wide range of both water- and oil-based systems. Excess lime buffers pH, provides a reserve quantity of calcium to precipitate soluble carbonates, and activates fatty-acid, oil-based additives. Lime is used for both calcium and pH control in gyp and lime systems. An alkaline pH that is buffered by excess lime will prevent acidic conditions from occurring, which can lead to accelerated corrosion from acid gases.

The solubility of lime increases with increased salinity but decreases with increased calcium, increased pH, and increased temperature.

Advantages

Widely available economical source of calcium and alkalinity

Toxicity and handling

Bioassay information is available upon request. Handle as an industrial chemical, wearing protective equipment and observing the precautions as described on the Transportation and Material Safety Data Sheet (MSDS).

Avoid exposure and handle only when fully protected. Lime is an alkaline material and can burn eyes, skin and respiratory tract, and may react violently with water or acids.

Lime should be added slowly to the mud system through a properly designed mud hopper. Do not mix lime with other chemicals or through the chemical barrel (due to its limited solubility, it will settle).

Packaging and storage

Lime is usually packaged in 22.7-kg [50-lbm] and 25-kg [55-lbm], multiwall paper sacks; numerous other sack sizes are used.

Store in a dry area away from water and acids. Keep all containers sealed. Once a container is opened, it should be used immediately. Lime is highly reactive and may be corrosive to certain materials. Spills should be cleaned up using protective equipment as described on the MSDS and with the utmost care.

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