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.
Formation of scale from radioactive components is monitored with a radiation detector. Upon indication of initiation of scale formation in a system, treatment with inhibitor is carried out.
A method for treating a subterranean formation, or a well penetrating the formation, comprises injecting into the well an aqueous composition containing an aminopolycarboxylic acid and water-soluble organosilicon compound. By use of the method, scale is removed from well equipment and/or openings in the formation, and fine particles within the formation are stabilized to prevent their subsequent movement, resulting in increased, more stable fluid flow through the formation and well.
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 macrocyclic polyether containing at least two nitrogen-linked phosphomethyl groups and enough monovalent basic compound to provide a solution pH of about 8.
A method and composition for removing barium and strontium sulfate scale deposits. The composition comprises an aqueous solution having a pH of about 8 to about 14, an EDTA or DTPA chelant, and a catalyst or synergist. Preferred chelants comprise diethylenetriaminepentaacetic acid (DTPA) or ethylenediaminetetraacetic acid (EDTA or alkali salts thereof. Anions of organic and inorganic acids comprise the catalyst. Catalysts which can be used include fluoride, oxalate, persulfate, dithionate, hypochlorite and formate anions. When the solution containing the composition is contacted with a surface containing a scale deposit, the deposit dissolves substantially more scale quicker than heretofore possible.
Alkaline earth metal scales, especially barium sulfate scale deposits are removed from oilfield pipe and other tubular goods with a scale-removing composition comprising an aqueous alkaline solution having a pH of about 8 to about 14, a polyaminopolycarboxylic acid, preferably EDTA or DTPA and a catalyst or synergist comprising oxalate anion. When the scale-removing solution is contacted with a surface containing a scale deposit, substantially more scale is dissolved at a faster rate than previously possible.
