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

Abstract

A dispersion solution for drilling obtained by dispersing, in an aqueous medium, a polyoxalate as the hydrolysable resin material. The dispersion solution for drilling comprises an aqueous medium in which is dispersed the hydrolysable resin material that exhibits a high hydrolysable capability at a temperature of as low as 80° C. or lower and, specifically, 60° C. or lower. The dispersion solution for drilling is used for the well drilling method such as hydraulic fracturing method, rotary drilling method or riserless drilling method.

1 . A dispersion solution for drilling obtained by dispersing, in an aqueous medium, a polyoxalate as the hydrolysable resin material. 
     
     
         2 . A method of extracting underground natural resources through a well formed by drilling, comprising the step of introducing the dispersion solution described in  claim 1  into under the ground with pressure to hydrolyze the hydrolysable resin material in hot water of not lower than 40° C. 
     
     
         3 . The extraction method according to  claim 2 , wherein the dispersion solution for drilling is introduced with pressure into the well to generate cracks in the vicinities of the well. 
     
     
         4 . The extraction method according to  claim 3 , wherein the well is filled with the hydrolysable resin material. 
     
     
         5 . The extraction method according to  claim 3 , wherein the dispersion solution for drilling is blended with a gelling agent, a gel is formed in the well with an acid released by the hydrolysis of the hydrolysable resin material and, thereafter, the gel is decomposed.