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.
The present invention provides for methods of inhibiting the formation and deposition of barium sulfate on the surfaces of papermaking systems. The inventive treatments comprise adding an effective amount of a poly(amine) compound to the papermaking systems. Representative polymers include polyallylamine, polytrimethylallylammonium chloride and polyvinylamine.
Metal-chelating liquids having the formula ##STR1## wherein Y is oxygen or ##STR2## R.sub.1 is hydrogen, alkyl, arylalkyl aryl, alkoxy, hydroxyalkyl ##STR3## wherein G is ##STR4##
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.
The invention provides a process for the sequestration of barium sulfate scale and barium sulfate sequestrant compositions therefor comprising an aqueous solution of citric acid (CA), a polycarbazic acid (PA), and an alklyenepolyaminopolycarboxylic acid (APAPCA), the weight ratio of CA to APAPCA being in the range from about 0.5 to 1 to about 11 to 1 and the weight ratio of PCA to APAPCA being in the range from about 0.002 to about 0.2, wherein the polycarbazic acid has the formula (R).sub.2 --N--[CH.sub.2 CH.sub.2 N(R)].sub.m --R where R is the group CH.sub.2 --CO--NH--NH--COOH and m is 0 or an integer from 1 to about 4, and wherein the APAPCA has the formula (HOOC--CH.sub.2).sub.2 --N--[CH.sub.2 --CH.sub.2 --N(CH.sub.2 --COOH)].sub.n --CH.sub.2 COOH where n is an integer from 1 to about 4. The preferred aqueous sequestering solution has a pH in the range from about 9.5 to about 14, said pH being provided by a base selected from the group consisting of potassium hydroxide, potassium carbonate, and mixtures thereof.
Deposit formation on the contact surfaces of structures containing heated hydrocarbon fluids such as refinery units, particularly units associated with the distilling process such as preheating stages, is inhibited by incorporating in the feed stock from 0.0001 to 0.01 weight percent of the combination of thiophene-containing polycondensed aromatic/naphthenic compounds of number average molecular weight (Mn) from 200 to 1000 and a macrocyclic polyamine of 2 to 8 nitrogen atoms per molecule and, if desired, at least one other additive such as an oil-soluble dispersant, antioxidant, antipolymerant, anti-foulant and mixtures thereof into said hydrocarbon stream.
