Dispersion solution for drilling and method of extracting underground resources using the dispersion solution

Patent metadata

Field	Value
Publication number	US-10040983-B2
Application number	US-201314649947-A
Country	US
Kind code	B2
Filing date	Dec 12, 2013
Priority date	Dec 12, 2012
Publication date	Aug 7, 2018
Grant date	Aug 7, 2018

Abstract

A dispersion solution for drilling obtained by dispersing, in an aqueous medium, a hydrolysable resin material that contains a resin that is hydrolysable but sparingly and a hydrolysable resin that accelerates the decomposition of esters. The dispersion solution for drilling exhibits a highly hydrolysable capability despite of using an inexpensive hydrolysable resin material, and can be favorably used for extracting resources relying on a well drilling method such as hydraulic fracturing method, rotary drilling method or riserless drilling method.

First claim

The invention claimed is:

1. A method of extracting underground resources through a well formed by drilling, comprising:
preparing a hydrolysable resin material composed of a mixture of 100 parts by weight of polylactic acid and not less than 40 parts by weight of polyoxalate;
introducing the hydrolysable resin material and an enzyme into water that contains no organic solvent to prepare a dispersion solution for drilling; and
introducing the dispersion solution for drilling into the well with pressure to hydrolyze the hydrolysable resin material in water at a temperature of from 40° C. to 50° C.

2. The method of extraction according to claim 1 , wherein the dispersion solution for drilling is introduced into the well with pressure to form a filter cake of solid components contained in the dispersion solution on the wall surfaces of the well, and said filter cake is decomposed with an acid released by the hydrolysis of the hydrolysable resin material.

3. The method of extraction according to claim 1 , wherein minerals in the vicinities of the well are dissolved with the acid produced by the hydrolysis of the hydrolysable resin material to thereby form cracks in the vicinities of the well.

4. The method of extraction according to claim 1 , wherein the well is filled with the hydrolysable resin material.

5. The method of extraction according to claim 1 , wherein the dispersion solution for drilling is blended with a gelling agent, a gel is formed in the well with the acid released by the hydrolysis of the hydrolysable resin material and, thereafter, the gel is decomposed.

6. The method of extraction according to claim 1 , wherein the enzyme is at least the one selected from protease, lipase and cutinase.

Assignees

• Toyo Seikan Group Holdings Ltd

Inventors

• Yoshikawa Seishi
• Katayama Tsutaki

Classifications

• E21B37/06

  using chemical means for preventing or limiting {, e.g. eliminating,} the deposition of paraffins or like substances · CPC title

• C09K8/12 Primary

  containing synthetic organic macromolecular compounds or their precursors · CPC title

• C09K8/508

  macromolecular compounds {(C09K8/512 takes precedence)} · CPC title

• E21B43/26

  by forming crevices or fractures · CPC title

• C09K8/08

  containing natural organic compounds, e.g. polysaccharides, or derivatives thereof · CPC title