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

Patent metadata

Field	Value
Publication number	US-11732547-B2
Application number	US-201817045366-A
Country	US
Kind code	B2
Filing date	May 24, 2018
Priority date	Apr 3, 2018
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

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 rigless plugging of an offshore wellbore having a casing and cement surrounding the casing and traversing a formation, comprising:
locating a relatively permeable layer of the formation adjacent a relatively impermeable cap rock layer of the formation;
preparing an interface of said formation and said wellbore at said relatively permeable 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 relatively permeable layer to form a cavity with a shoulder;
using a wellbore bismuth alloy deployment tool, deploying 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;
applying pressure to the liquid bismuth alloy to force some of the liquid bismuth alloy into the permeable layer;
permitting said bismuth alloy to solidify to form a plug in said wellbore and in said permeable layer 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 formation fluid pressure; and
determining an amount of bismuth alloy to deploy, wherein said determining an amount of bismuth alloy comprises determining a minimum volume of bismuth alloy V TA +V a where V TA is a total bismuth alloy volume other than cylindrical portions of the plug and V a is a bismuth alloy volume of the cylindrical portions of the plug, and V TA =V A +V C +V u where V A is a volume that penetrates into the relatively permeable layer, V C is a volume of the grooves, if any, etched into the relatively impermeable layer, and V u is a volume in the barrier below the cavity.

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

3. The method of claim 1 , wherein said determining an amount of bismuth alloy comprises determining the bismuth alloy volume of the cylindrical portions of the plug substantially according to
where n is a radius of the cavity, r c is a radius of the casing, H c is a height of the cavity where the casing is removed, H is a melted alloy height required to obtain an excess pressure of the plug, V R is a casing volume removed above H c , and V T is a volume of a tapered area, if any, of said shoulder.

4. A method for rigless plugging of an offshore wellbore having a casing and cement surrounding the casing and traversing a formation, comprising:
locating a relatively permeable layer of the formation adjacent to a relatively impermeable cap rock layer of the formation;
preparing an interface of said formation and said wellbore at said relatively permeable 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 relatively permeable layer to form a cavity with a shoulder;
using a wellbore bismuth alloy deployment tool, deploying 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;
applying pressure to the liquid bismuth alloy to force some of the liquid bismuth alloy into the permeable layer; and
permitting said bismuth alloy to solidify to form a plug in said wellbore and in said permeable layer 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 formation fluid pressure, and wherein said applying pressure comprises utilizing a wellbore tool assembly including a packer and said wellbore bismuth alloy deployment tool; deploying said packer at a relatively impermeable layer of the formation; locating a tool body of the wellbore bismuth alloy deployment tool so that it extends through the packer in the wellbore with said wellbore bismuth alloy deployment tool comprising a fluid passageway having a fluid inlet located above the packer, a fluid outlet located below the packer, and a pump between said fluid inlet and fluid outlet for pumping fluid from above the packer to below the packer in the wellbore, said tool body including a bismuth alloy storage chamber storing bismuth alloy and adapted to release the bismuth alloy into the wellbore.

5. The method of claim 4 , wherein said preparing an interface further comprises preparing said interface both at the permeable layer of the formation and along a portion of the adjacent relatively impermeable cap rock layer in the formation.

6. The method of claim 5 , wherein said preparing an interface comprises etching at least one continuous groove in the formation at the relatively impermeable cap rock layer of the formation.

7. The method of claim 6 , wherein said etching at least one continuous groove comprises etching at least one helical groove.

8. The method of claim 6 , 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.

9. The method of claim 6 , 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.

10. The method of claim 4 , further comprising, prior to deploying said amount of bismuth alloy into the wellbore, deploying a barrier in the wellbore just at or below a continuous groove in the formation.

11. The method of claim 10 , further comprising, determining an amount of bismuth alloy to deploy, wherein said determining an amount of bismuth alloy comprises determining a minimum volume of bismuth alloy V TA +V a where V TA is a total bismuth alloy volume other than cylindrical portions of the plug and V a is a bismuth alloy volume of the cylindrical portions of the plug, and V TA =V A +V C +V u where V A is a volume that penetrates into the relatively permeable layer, V C is a volume of the grooves, if any, etched into the relatively impermeable layer, and V u is a volume in the barrier below the cavity.

12. The method of claim 11 , wherein said determining an amount of bismuth alloy comprises determining the bismuth alloy volume of the cylindrical portions of the plug substantially according to
where n is a radius of the cavity, r c is a radius of the casing, H c is a height of the cavity where the casing is removed, H is a melted alloy height required to obtain an excess pressure of the plug, V R is a casing volume removed above H c , and V T is a volume of a tapered area, if any, of said shoulder.

13. The method of claim 4 , 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.

14. The method of claim 4 , wherein said plug comprises a solid bismuth alloy material having a solid first cylindrical body portion, a dendritic web extending outwardly from and around at least a portion of said solid first cylindrical body portion, a solid second cylindrical body portion of smaller diameter than the first cylindrical body portion, and a shoulder being defined at a transition from said first cylindrical body portion to said second cylindrical body portion.

15. The method of claim 4 , wherein said plug comprises a solid bismuth allo

Assignees

• Schlumberger Technology Corp

Inventors

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