Method and apparatus for filling an annulus between casing and rock in an oil or gas well

Patent metadata

Field	Value
Publication number	US-10975657-B2
Application number	US-201916668841-A
Country	US
Kind code	B2
Filing date	Oct 30, 2019
Priority date	Feb 13, 2015
Publication date	Apr 13, 2021
Grant date	Apr 13, 2021

Abstract

The invention relates to the decommissioning of hydrocarbon wells. It concerns the artificial promoting or inducing of creep in the overburden formation 3 surrounding an oil well 1 , so that the formation rock 3 encroaches against the casing 5 to form a seal. This avoids the need to plug the annulus between the casing 5 and formation 3 with cement. The overburden may be caused to creep by reducing the pressure in the annulus, by applying heat to the overburden rock or by stressing the rock repeatedly to cause fatigue in the rock 3.

First claim

The invention claimed is:

1. A process for plugging an annulus between casing and formation in a hydrocarbon wellbore during a plug and abandon operation, the process comprising placing the well in an underbalanced state with an underbalance of between 2.76 MPa and 27.6 MPa, thereby artificially promoting or inducing creep in the formation surrounding the casing and plugging the annulus only with the formation.

2. The process according to claim 1 which further comprises a step of substantially equalizing pressure between the annulus and the interior of the casing by perforating or puncturing the casing in order to achieve said equalization of pressure between the annulus and the interior of the casing.

3. The process according to claim 1 which further comprises a step of substantially equalizing pressure between the annulus and the interior of the casing passing coil tubing down the wellbore in order to achieve said equalization of pressure between the annulus and the interior of the casing.

4. The process according to claim 1 which further comprises a step of substantially equalizing pressure between the annulus and the interior of the casing, wherein said equalization of pressure between the annulus and the interior of the casing is achieved via casing valve outlets in the wellhead.

5. The process according to claim 1 which further comprises applying heat to the formation and wherein the temperature is elevated by between 5 and 50 degrees Celsius.

6. The process according to claim 1 which further comprises stressing the formation and wherein the stressing step is repeated with the objective of fatiguing the formation.

7. The process according to claim 6 wherein the repeated stressing is achieved by repeatedly increasing and reducing the pressure in the annulus.

8. The process according to claim 7 wherein the pressure in the annulus is increased and reduced via fluid in the annulus.

9. The process according to claim 7 wherein the pressure is varied over a range of plus or minus 2.76 MPa (400 psi) and 27.6 MPa (4,000 psi).

10. The process according to claim 7 wherein the pressure is cycled between 5 and 50,000 times.

11. The process according to claim 1 which further comprises stressing the formation including directly stressing the formation using a mechanical device comprising a mechanical vibrator, a seismic vibrator, or other vibrational source.

12. The process according to claim 1 wherein the underbalance is between 4.14 MPa and 13.8 MPa.

13. The process according to claim 1 wherein the underbalance is achieved by using seawater in the string.

14. The process according to claim 1 wherein the underbalance is achieved by using gas under production in the string.

15. The process according to claim 1 wherein the underbalance is achieved by using oil in the string.

Assignees

• Conocophillips Co

Inventors

• Watts Rick D
• Tompkins Dianne
• Haneferd Helen
• Hovda Lars
• Omdal Edvard
• Nielsen Hardy Hartmann
• Vedvik Lars
• Husby Tove

Classifications

• E21B36/04 Primary

  using electrical heaters · CPC title

• E21B33/13 Primary

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