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

Patent metadata

Field	Value
Publication number	US-2016237779-A1
Application number	US-201615042814-A
Country	US
Kind code	A1
Filing date	Feb 12, 2016
Priority date	Feb 13, 2015
Publication date	Aug 18, 2016
Grant date	—

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

1 . A process for plugging an annulus between casing and formation in a hydrocarbon wellbore by artificially promoting or inducing creep in formation surrounding the casing.

2 . The process according to claim 1 including the step of substantially equalizing pressure between the annulus and the interior of the casing and/or placing the well in an underbalanced state.

3 . The process according to claim 2 including the step of perforating or puncturing the casing in order to equalize the pressure between the annulus and the interior of the casing.

4 . The process according to claim 3 including the step of passing coil tubing down the wellbore and controlling pressure within the casing and in the annulus via the coil tubing.

5 . The process according to claim 2 including the step of controlling pressure in the annulus via casing valve outlets in the wellhead.

6 . The process according to claim 1 including the step of applying heat to formation surrounding the casing.

7 . The process according to claim 6 wherein the temperature is elevated by between 0.5 and 50 degrees Celsius.

8 . The process according to claim 1 including the step of stressing formation surrounding the casing.

9 . The process according to claim 8 wherein the stressing step is repeated with the objective of fatiguing the formation.

10 . The process according to claim 9 wherein the repeated stressing is achieved by repeatedly increasing and reducing the pressure in the annulus.

11 . The process according to claim 10 wherein the pressure in the annulus is increased and reduced via liquid, such as drilling, completion or workover fluid in the annulus.

12 . The process according to claim 10 wherein the pressure is varied over a range of plus or minus 2.76 MPa (400 psi) and 27.6 MPa (4,000 psi).

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

14 . The process according to claim 8 including directly stressing the formation using a mechanical device including a mechanical vibrator, a seismic vibrator, or other vibrational source.

Assignees

• Conocophillips Co

Inventors

• Husby Tove
• Watts Rick D
• Tompkins Dianne
• Haneferd Helen
• Hovda Lars

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

• E21B33/14 Primary

  for cementing casings into boreholes · CPC title