Methods, apparatus and systems for creating wellbore plugs for abandoned wells

Patent metadata

Field	Value
Publication number	US-2023272689-A1
Application number	US-202318313423-A
Country	US
Kind code	A1
Filing date	May 8, 2023
Priority date	Apr 3, 2018
Publication date	Aug 31, 2023
Grant date	—

Abstract

A wellbore is plugged using a bismuth alloy. The wellbore is arranged so that a liquid bismuth alloy sets with an excess pressure of the plug relative to the borehole fluid pressure along a desired seal height distance.

First claim

What is claimed is:

1 . A method for the rigless plugging of an offshore wellbore having a casing and cement surrounding the casing and traversing a formation, comprising:
locating an impermeable layer of the formation; preparing an interface of said formation and said wellbore in said impermeable layer by using a tool extended by wireline, slickline or coiled tubing into the wellbore to remove the casing and cement along a selected portion of the wellbore along said impermeable layer to form a cavity with a shoulder, and etching at least one continuous groove in the impermeable layer at the interface to generate a pathway for borehole fluid to move upwards and above said prepared interface; deploying, using a wellbore bismuth alloy deployment tool, bismuth alloy into the wellbore at said prepared interface and into the casing above said prepared interface; causing the deployed bismuth alloy to become liquid; permitting said bismuth alloy to solidify in said wellbore and force fluid in the pathway upwards, to form a plug in said wellbore at said prepared interface and into the casing above said prepared interface with an excess pressure of the alloy as it solidifies along a desired seal height distance relative to the fluid pressure in the wellbore below the alloy of the plug.

2 . The method of claim 1 , wherein said etching at least one continuous groove comprises etching at least one helical groove.

3 . The method of claim 1 , wherein said etching at least one continuous groove comprises etching a plurality of vertical grooves and a plurality of grooves having a horizontal component connecting said vertical grooves.

4 . The method of claim 1 , wherein said preparing an interface comprises etching at least one second groove in fluid communication with said at least one continuous groove at the shoulder between the cement and casing and rock of the impermeable layer.

5 . The method of claim 1 , further comprising, prior to deploying said bismuth alloy into the wellbore, deploying a barrier in the wellbore just at or below the groove in the formation.

6 . The method of claim 5 , further comprising, determining an amount of bismuth alloy to deploy, wherein said determining an amount of bismuth alloy comprises determining a volume of bismuth alloy V substantially according to V=πr c 2 H+π(r b 2 −r c 2 )H c +V u , where r b is the radius of the cavity, r c is the radius of the casing, V u is the volume in the barrier below the cavity, H c is the height of the cavity where the casing is removed, and a H is a melted alloy height required to obtain said excess pressure of the plug.

7 . The method of claim 1 , wherein said preparing an interface of said formation and said wellbore further comprises preparing said interface by angling said shoulder to cause the cavity to taper.

8 . The method of claim 1 , wherein said plug comprises a solid bismuth alloy material having a solid first cylindrical body portion, a solid second cylindrical body portion of smaller diameter than the first cylindrical body portion, a shoulder being defined at a transition from said first cylindrical body portion to said second cylindrical body portion, and at least one continuous thread extending proud of and running along the first cylindrical body portion to the top of the cylindrical first body portion.

9 . A formation plug formed in situ in a wellbore traversing a formation, comprising:
solid bismuth alloy material having a solid first cylindrical body portion, a solid second cylindrical body portion of smaller diameter than the first cylindrical body portion, a shoulder being defined at a transition from said first cylindrical body portion to said second cylindrical body portion, and at least one continuous thread extending proud of and running along the first cylindrical body portion to the top of the cylindrical first body portion.

10 . A formation plug according to claim 9 , wherein said at least one thread comprises at least one helical thread.

11 . A formation plug according to claim 9 , wherein said at least one thread comprises a plurality of threads.

12 . A formation plug according to claim 11 , wherein said plurality of threads comprises a plurality of vertical threads and a plurality of additional threads having horizontal components and coupling said plurality of vertical threads.

13 . A formation plug according to claim 9 , wherein said shoulder is tapered.

14 . A formation plug according to claim 9 , wherein said shoulder includes at least one additional thread extending upward in the direction of said second cylindrical portion.

15 . A formation plug according to claim 14 , wherein said at least one additional thread forms a spiral.

16 . A formation plug according to claim 9 , wherein said plug further comprises a conical portion extending from an end of said first cylindrical body portion.

17 . A method for the rigless plugging of an offshore wellbore having a casing and cement surrounding the casing and traversing a formation, comprising:
locating an impermeable layer of the formation; preparing an interface of said formation and said wellbore in said impermeable layer by extending a tool into the wellbore without a rig to remove the casing and cement along a selected portion of the wellbore along said impermeable layer to form a cavity with a shoulder, and etching at least one continuous groove in the impermeable layer at the interface to generate a pathway for borehole fluid to move upwards and above said prepared interface; deploying, using a wellbore bismuth alloy deployment tool, bismuth alloy into the wellbore at said prepared interface and into the casing above said prepared interface; causing the deployed bismuth alloy to become liquid; permitting said bismuth alloy to solidify in said wellbore and force fluid in the pathway upwards, to form a plug in said wellbore at said prepared interface and into the casing above said prepared interface with an excess pressure on the alloy along a desired seal height distance relative to the fluid pressure in the wellbore below the alloy of the plug.

18 . The method of claim 17 , further comprising, prior to said deploying the bismuth alloy into the wellbore, deploying a barrier in the wellbore just at or below the groove in the formation, and determining an amount of bismuth alloy to deploy, wherein said determining an amount of bismuth alloy comprises determining a volume of bismuth alloy V substantially according to V=πr c 2 H+π(r b 2 −r c 2 )H c +V u , where r b is the radius of the cavity, r c is the radius of the casing, V u is the volume in the barrier below the cavity, H c is the height of the cavity where the casing is removed, and a H is a melted alloy height required to obtain said excess pressure of the plug.

Assignees

• Schlumberger Technology Corp

Inventors

• Ramakrishnan Terizhandur S
• Zhang Hua
• Elias Quincy K
• Perez Albert

Classifications

• E21B33/1212 Primary

  including a metal-to-metal seal element · CPC title

• E21B33/13 Primary

  Methods or devices for cementing, for plugging holes, crevices or the like · CPC title

• C09K8/426

  for plugging · CPC title

• C09K8/46

  containing inorganic binders, e.g. Portland cement · CPC title

• C22C12/00 Primary

  Alloys based on antimony or bismuth · CPC title