Dispersion solution for drilling and method of extraction using the dispersion solution

A method of extracting underground natural resources through an ore chute located in a temperature region where temperature in the region is not higher than 60° C.,

• the method comprising introducing a dispersion solution into the ore chute with pressure,
• wherein the dispersion solution is obtained by dispersing, in water, a hydrolyzable resin pellet that contains a polyoxalate having a ratio of decomposition higher than 40% when the pellet is stored for 4 days at 45° C. in distilled water, in order to hydrolyze the hydrolyzable resin pellet to extract underground natural resources.