Shell Oil Comapny

Shell Development Company

David N Reinhoudt

Feike De Jong

Robin T Gray

Gerridina J Torny-Schutte

Reike De Jong

Barium sulfate scale is dissolved by contacting it with an aqueous solution of: a bicyclic macrocyclic polyether in which the intramolecular cavity or cript is preferentially receptive to the cations of alkaline earth metals, at least a catalytically effective proportion of an alkali metal salt of an organic acid, and enough dissolved alkaline inorganic alkali metal or ammonium compound to provide a solution pH of at least about 8.

Dissolving barium sulfate scale with aqueous solutions of bicyclic

Novel complexes of macrocyclic polyethers such as 1,4,7,10,13,16-hexaoxacyclooctadecane (18-crown-6) and disulfonates of the formula I ##STR1## wherein X represents barium or strontium and R.sup.1 is an alkylene moiety, optionally substituted with an alkyl group, are described as well as a process for isolating said macrocylic polyethers through formation of said novel complexes. In the isolation process disclosed, a macrocyclic polyether containing solution is contacted with a disulfonate of formula I to afford the polyether-disulfonate complex as a solid suspension in the solution, the suspended complex is separated from the solution and the separated complex is extracted with a solvent for the macrocyclic polyether.

Macrocyclic polyether complexes

Barium sulfate scale can be removed from remote locations such as those in or around the borehole of a well extending into a subterranean earth formation by contacting the scale with an aqueous solution consisting essentially of water,a monovalent cation salt of a monocyclic macrocyclic polyamine containing at least two nitrogen-linked carboxymethyl groups and enough monovalent basic compound to provide a solution pH of about 8.

Dissolving barium sulfate scale with aqueous solutions of salts of

Macrocyclic polyethers, their preparation, complexes of these macrocyclic polyethers and their preparation are described.

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Amsterdam, Netherlands

David N Reinhoudt