Degradable seal member for downhole tools, downhole tool, and method of well drilling and completion

Patent metadata

Field	Value
Publication number	US-2016290091-A1
Application number	US-201415037352-A
Country	US
Kind code	A1
Filing date	Dec 25, 2014
Priority date	Dec 27, 2013
Publication date	Oct 6, 2016
Grant date	—

Abstract

Provided is a degradable seal member for downhole tools, the member being formed from a degradable polymer material that is preferred to be a thermoplastic polymer material or a polymer material including an ester bond, an amide bond, or a urethane bond, and that is further preferred to be a polymer material that contains an aliphatic polyester. It is preferred that the degradable seal member exhibits a bending elastic modulus of 0.01 to 8 GPa at 23° C., further preferred that a stable state is maintained in a dry environment and that degradation in a fluid of a temperature not less than 66° C. is possible, and also preferred that a molded article has an annular shape. Also provided are a downhole tool such as a plug for well drilling and completion, and a method of well drilling and completion.

First claim

1 . A degradable seal member for downhole tools comprising a degradable polymer material.

2 . The degradable seal member for downhole tools according to claim 1 , wherein a bending elastic modulus at 23° C. is from 0.01 to 8 GPa.

3 . (canceled)

4 . The degradable seal member for downhole tools according to claim 1 , wherein the member maintains a stable state in a dry environment and is degradable in fluid of a temperature of not less than 66° C.

5 . The degradable seal member for downhole tools according to claim 1 , wherein a decrease rate of a 50% strain compressive stress of the degradable polymer material after immersion for 24 hours in 150° C. water relative to a 50% strain compressive stress before immersion is not less than 5%.

6 . The degradable seal member for downhole tools according to claim 1 , wherein a loss rate of mass of the degradable polymer material after immersion for 72 hours in 150° C. water relative to a mass before immersion is from 5 to 100%.

7 . (canceled)

8 . The degradable seal member for downhole tools according to claim 1 , wherein the degradable polymer material contains not less than two types of degradable polymer material.

9 . The degradable seal member for downhole tools according to claim 1 , wherein the degradable polymer material contains a polymer material containing at least one ester bond, amide bond, or urethane bond.

10 . The degradable seal member for downhole tools according to claim 1 , wherein the degradable polymer material contains an aliphatic polyester.

11 . The degradable seal member for downhole tools according to claim 10 , wherein the aliphatic polyester is a copolymer.

12 . The degradable seal member for downhole tools according to claim 10 , wherein the aliphatic polyester contains at least one type selected from the group consisting of polylactic acid, stereocomplex-type polylactic acid, polybutylene succinate, polybutylene adipate/terephthalate, and polybutylene succinate/adipate.

13 . The degradable seal member for downhole tools according to claim 1 , wherein the degradable polymer material contains an acidic substance (which may also be an acid-producing substance).

14 . The degradable seal member for downhole tools according to claim 1 , wherein the degradable polymer material contains a reinforcing material.

15 . The degradable seal member for downhole tools according to claim 1 , wherein a tensile fracture strain is not less than 20%.

16 . The degradable seal member for downhole tools according to claim 1 , wherein the member is an annular molded article disposed on an outer circumferential surface orthogonal to an axial direction of a mandrel provided in a downhole tool.

17 . A downhole tool comprising:
the degradable seal member for downhole tools described in claim 1 .

18 . A method for well drilling and completion, the method comprising:
sealing a fluid between a downhole tool and a casing using the degradable seal member for downhole tools described in claim 1 .

19 . A method for well drilling and completion, the method comprising:
performing isolation treatment of a borehole using the degradable seal member for downhole tools described in claim 1 , and then the downhole tools being degraded.

20 . A method for well drilling and completion, the method comprising:
sealing a borehole using a downhole tool comprising a degradable seal member for downhole tools formed from a degradable polymer material and having a bending elastic modulus at 23° C. of 0.01 to 8 GPa, and maintaining a stable state in a dry environment and being degradable in fluid of a temperature of not less than 66° C.; and then the degradable seal member for downhole tools being degraded inside the borehole.

21 . A method for well drilling and completion according to claim 20 , the method comprising:
sealing a borehole using a downhole tool further comprising another member for downhole tools containing a degradable material; and then the degradable seal member for downhole tools being degraded inside the borehole.

22 . (canceled)

23 . A method for well drilling and completion, the method comprising:
performing well treatment using a downhole tool comprising a degradable seal member for downhole tools formed from a degradable polymer material and having a bending elastic modulus at 23° C. of 0.01 to 8 GPa, and maintaining a stable state in a dry environment and being degradable in fluid of a temperature of not less than 66° C., the degradable seal member for downhole tools being in contact with another member for downhole tools; and then the degradable seal member for downhole tools being degraded inside the borehole.

Assignees

• Kureha Corp

Inventors

• Takahashi Takeo
• Okura Masayuki
• Kobayashi Takuma

Classifications

• E21B43/26

  by forming crevices or fractures · CPC title

• C08L67/04

  Polyesters derived from hydroxycarboxylic acids, e.g. lactones (C08L67/06 takes precedence) · CPC title

• E21B33/12 Primary

  Packers; Plugs (used for cementing E21B33/134, E21B33/16) · CPC title

• E21B2200/08

  Down-hole devices using materials which decompose under well-bore conditions · CPC title

• E21B43/27

  by use of eroding chemicals, e.g. acids · CPC title