Water solution, clean fracturing fluid and method for fracturing reservoir

A method for fracturing a reservoir, comprising:

• preparing an aqueous solution by:
• mixing an organic acid amidopropyl dimethylamine, an additive, and water, while stirring at a temperature of 30° C. to 50° C. for a time of 5 min to 20 min,
• wherein the additive is selected from the group consisting of salicylate, cis-butenedioic acid, o-phthalic acid, dodecyl sulfonate, p-toluene sulfonate, benzoate and combinations thereof,
• wherein a weight ratio of the organic acid amidopropyl dimethylamine and the additive is 8:1-12:1;
• introducing carbon dioxide at a rate of 0.1-0.5 L/min. into the aqueous solution for gelatinization, to form a clean fracturing fluid,
• wherein the carbon dioxide is introduced for a time sufficient render the clean fracturing fluid clear;
• injecting the clean fracturing fluid into a reservoir for fracturing;
• and
• introducing air, nitrogen, or an inert gas into the reservoir after the fracturing for gel breaking.