Fluids

Use of a composition as, or as a component of, a drilling, completion or workover fluid. The composition comprises an organic liquid selected from an alcohol, glycol and glycol ether having dissolved and/or suspended therein at least one Group I or Group II metal salt. The metal salt may be an inorganic salt. The metal salt may be a halide, carboxylate or carbonate salt of a Group I or Group II metal such as sodium chloride, sodium bromide, potassium chloride, potassium bromide, magnesium chloride, calcium bromide and mixtures thereof. The metal salt may be a blend of two or more Group I and/or Group II metal salts such as sodium chloride / sodium bromide, caesium formate / potassium formate or caesium formate / sodium formate. For example the composition may comprise monoethylene glycol, in combination with calcium chloride and/or calcium bromide. The composition may be used as a weighting agent in a drilling, completion or workover fluid. Methods of drilling, completing or workover of a well, which may be a hydrocarbon well, are carried out in the presence of the composition.