A method of removing a sulfate scale from a surface is provided. The method includes contacting the sulfate-comprising scale with a conversion solution including 1 to 10 wt. % of an alkali metal carbonate, 0.5 to 10 wt. % of a borate salt or hydrate thereof, and 0.5 to 2.5 wt. % of a base to produce a carbonate-comprising scale. The method further includes exposing the carbonate-comprising scale with an acid solution including 2.5 to 25 wt. % of an acid.