2. . 
Saline liquid usually used in completion operations and, increasingly, when penetrating a pay zone. Brines are preferred because they have higher densities than fresh water but lack solid particles that might damage producible formations. Classes of brines include chloride brines (calcium and sodium), bromides and formates.
3. . 
A general term that refers to various salts and salt mixtures dissolved in an aqueous solution. Brine can be used more strictly, however, to refer to solutions of sodium chloride. We prefer to use brine as a general term. Clear brines are salt solutions that have few or no suspended solids.
4. . 
A water-based solution of inorganic salts used as a well-control fluid during the completion and workover phases of well operations. Brines are solids free, containing no particles that might plug or damage a producing formation. In addition, the salts in brine can inhibit undesirable formation reactions such as clay swelling. Brines are typically formulated and prepared for specific conditions, with a range of salts available to achieve densities ranging from 8.4 to over 20 lbm/gal (ppg) [1.0 to 2.4 g/cmo]. Common salts used in the preparation of simple brine systems include sodium chloride, calcium chloride and potassium chloride. More complex brine systems may contain zinc, bromide or iodine salts. These brines are generally corrosive and costly.