Interaction between drilling and completion fluids and various minerals is unavoidable when fluids circulate through many thousands of metres of different formation types. When thick sections of salt anhydrate are drilled, it is especially important that the drilling fluid does not dissolve large amounts of formation. Equally, when drilling fluid filtrates and completion brines invade the reservoir and contact the formation brine, it is imperative that insoluble scales are not formed.

The ability of formate well construction fluids to interact with minerals or form scales in the reservoir is determined by the solubility of various minerals and salts in formate brines. This section of the formate manual looks at what is known about the solubility of minerals and salts in formate brines. Formate brines have a unique ability to dissolve alkaline earth metal sulfates, such as barium sulfate, and can serve as scale dissolvers or scale inhibitors for such scales. In addition to extensive solubility data for alkaline earth metal sulfates in formate brines, this section contains solubility data for some salts, such as potassium sulfate, sodium chloride, and magnesium chloride. Solubility data is also included for various clays, silicates, galena, hematite, Ilmenate, and calcium carbonate.