An oil well brine is the saline liquid that is used in oil well drilling completion operations while penetrating a bore well for oil and gas production. Brines are the most preferred choice in oil well drilling activities because they have higher densities than fresh water but lack solid particles that might damage producible formations. There are a variety of classes of brines like chloride brines (calcium and sodium), bromides and formates. Amongst these, the bromides, clear, chlorine-free brines are a popular choice as drilling fluids.
Calcium Bromide(CaBr2): A clear brine fluid, CaBr2 solution is used as a single salt brine in densities ranging from from 11.7 lbs/gal to 15.1 lbs/gal.
Sodium Bromide (NaBr): NaBr, a salt is used alone or in a combination with sodium chloride or Zinc Bromide to form clear workaround and drilling fluids with densities of 8.4-12.5 lbs/gal.
Zinc Bromide(ZnBr2): It is a clear, solid-free brine fluid with minimum density of 19.2 lbs/gal. It can be used with other bromides and chlorides to prepare non-damaging fluids with densities ranging from 15.1 lbs/gal to 19.2 lbs/gal.
While the above bromides serve as good high density Drilling Fluids, a combination of these fluids with each other or chlorides form excellent multi-salt liquids that form excellent drilling, completion, and packer fluids. The various multi-salt combinations formed by the above 3 bromides are as follows:
Zinc Bromide/Calcium Bromide blend:
It is used as a clear-brine workaround and completion fluid. This multi-salt brine, jointly known as zinc bromide, requires high-density fluids and can be blended with lower density brines and can be formulated with various crystallization points. It is a clear, solids free brine fluid of 19.2 lbs/gal density, with 53-58% ZnBr2 and 20.0-23.0% CaBr2. It can be blended with other solutions containing bromides and chlorides.
Calcium Bromide (CaBr2) /Calcium Chloride (CaCl2) blend:
It is a two-salt brine system ranging from 11.7 to 15.1 lb/gal densities. This density range is obtained by blending 11.6 lb/gal CaCl2 with 14.3 lb/gal CaBr2. This multi-salt brine is the most economically available clear brine solution.
Sodium Chloride (NaCl) /Sodium Bromide (NaBr) blend:
It is a clear brine fluid that is formulated to meet and crystallization temperature requirements and individual density, covering the density range from 8.4 lb /gal to 12.7 lb /gal. This blend is often used when the calcium ion is not desirable and costs are a concern, as it is less expensive than pure sodium bromide brines.
Thus, the bromides, meeting the desirable heavy densities for drilling oil well purposes and used as both single-salt & multi-salt liquids are the most desirable of the range of drilling fluids available.