Heavy fluid and method of making it

Abstract

Heavy fluids are made from calcium bromide and at least one hydrogen bond donor such as a low molecular weight polyol or an organic acid. The combination of a hydrogen bond donor and calcium bromide as a hydrogen bond acceptor in an appropriate molar ratio forms a higher density clear completion fluid at a low temperature not otherwise obtainable with heavy aqueous solutions of calcium bromide such as are used in oilfield wells. A method of making the fluid comprises mixing calcium bromide with the polyol(s) in the presence of water and then reducing the water content, thus forming a heavy fluid. A crystallization inhibitor such as nitrilotriacetamide or a particulate silicate is included in the formulation. When the heavy fluid 'freezes,' its physical form is somewhat amorphous and pumpable rather than crystalline. The heavy fluid is useful as a drilling fluid as well as a completion fluid and for other purposes in oil recovery processes where extreme density is beneficial.