DECOMMISSIONING OFFSHORE OIL AND GAS WELLS

• US 20150330048A1
• Filed: 05/12/2015
• Published: 11/19/2015
• Est. Priority Date: 05/19/2014
• Status: Active Grant

• Current Assignee: Conocophillips Company (ConocoPhillips)
• Original Assignee: Conocophillips Company (ConocoPhillips)
• Inventors: GARDER, Jean
• Granted Patent: US 9,366,091 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B63B 35/44 Floating buildings, stores, drilling platforms, or workshops, e.g. carrying water-oil separating devices construction methods for floating offshore platforms B63B75/00
• CPC Class Codes: E02B 17/00 Artificial islands mounted on piles or like supports, e.g. platforms on raisable legs or offshore constructions; Construction methods therefor construction methods for floating platforms B63B75/00; anchoring floating platforms B63B21/00; floating platforms, e.g. anchored, B63B35/44; underwater reservoirs B65D88/78
• CPC Class Codes: E02B 17/0034 Maintenance, repair or inspection of offshore constructions
• CPC Class Codes: E02B 2017/0052 Removal or dismantling of offshore structures from their offshore location
• CPC Class Codes: E02B 2017/0095 Connections of subsea risers, piping or wiring with the offshore structure
• CPC Class Codes: E21B 15/003 adapted to be moved on their substructure, e.g. with skidding means; adapted to drill a plurality of wells
• CPC Class Codes: E21B 15/02 specially adapted for underwater drilling E21B15/04 takes precedence
• CPC Class Codes: E21B 19/002 specially adapted for underwater drilling E21B19/09, E21B19/143 take precedence
• CPC Class Codes: E21B 19/16 Connecting or disconnecting pipe couplings or joints E21B19/20 takes precedence
• CPC Class Codes: E21B 29/00 Cutting or destroying pipes, packers, plugs or wire lines, located in boreholes or wells, e.g. cutting of damaged pipes, of windows; Deforming of pipes in boreholes or wells; Reconditioning of well casings while in the ground

Abstract

Method and structures perform decommissioning of offshore oil and gas platforms with associated wells. By installing on a platform (1) a movable decommissioning rig tower (2) but stripping away most of the other structures and equipment on the platform (1), and specifically not providing supporting resources such as drilling mud and power, accommodation, etc. on the platform, it is possible for both the rig tower (2) and a further rig tower (28) installed on a jack up rig (20) located alongside the platform (1) to access the well bay (5) of the platform. Thereby, two wells may be accessed simultaneously through the same well bay (5) and respective decommissioning operations carried out simultaneously and independently.

Claims

1. A method for decommissioning an offshore oil or gas platform, comprising the steps of:

a) providing a jack up rig, the jack up rig being equipped with one or more of an accommodation block, drilling mud supply and power supply, wherein the jack up rig has a cantilever structure extending over a side of the jack up rig, on which structure is mounted a first decommissioning rig tower;

b) maneuvering the jack up rig alongside the platform such that the cantilever and first decommissioning rig tower overlie a first well within a well bay of the platform;

c) installing on the platform a second decommissioning rig tower overlying a second well in the well bay of the platform; and

d) operating the first and second decommissioning rig towers and associated equipment with one or more of power, drilling mud and operator personnel from or housed on the jack up rig.

2. The method according to claim 1, wherein the jack up rig and first decommissioning rig tower are capable of supporting an operation of milling out a 10 meter length of well casing.

3. The method according to claim 1, wherein the jack up rig and second decommissioning rig tower are capable of supporting an operation of milling out a 10 meter length of well casing.

4. The method according to claim 1, wherein, in step (d), the first and second decommissioning rig towers are operated simultaneously.

5. The method according to claim 1, including moving one of the first and second decommissioning rig towers to overlie a third well in the well bay and commencing a down hole operation in the third well whilst the other of the first and second decommissioning rig towers is performing a down hole operation.

6. The method according to claim 1, wherein the platform has a further well bay and the method includes the step of moving either or both of the first and second decommissioning rig towers between wells in the respective well bays.

7. The method according to claim 1 wherein the platform has a second well bay and the method includes installing on the platform a third decommissioning rig tower overlying a well in the second well bay of the platform.

8. A combination of an offshore oil or gas platform being subject to decommissioning and a jack up rig, wherein:

a) the jack up rig is equipped with one or more of a drilling mud supply and power supply, and the jack up rig has a cantilever structure extending over a side of the jack up rig, on which structure is mounted a first decommissioning rig tower;

b) the jack up rig is located alongside the oil or gas platform such that the cantilever and first tower overlie a first well within a well bay of the platform;

c) the platform is equipped with a second decommissioning rig tower overlying a second well in the well bay of the platform; and

d) the second decommissioning rig tower is operable using one or more of the drilling mud supply and power supply from the jack up rig.

9. The combination according to claim 8, wherein the jack up rig and first decommissioning rig tower are capable of supporting the operation of milling out a 10 meter length of well casing.

10. The method according to claim 8, wherein the jack up rig and second decommissioning rig tower are capable of supporting the operation of milling out a 10 meter length of well casing.

11. The method according to claim 8, wherein the first and second decommissioning rig towers are capable of being operated simultaneously.

12. The method according to claim 8, wherein the first and/or second decommissioning rig tower is capable of being moved whilst the other of the first and second decommissioning rig towers is performing a down hole operation.

13. The method according to claim 8, wherein the platform has a further well bay and either or both of the first and second rig towers is capable of being moved between wells in the respective well bays.

14. The method according to claim 8 wherein the platform has a second well bay and a third decommissioning rig tower installed on the platform.

15. An oil or gas platform having installed thereon a movable decommissioning rig tower capable of supporting an operation of milling out a 10 meter length of well casing, the rig tower and associated equipment connected to a source of drilling mud and power, which is not located on the platform.

16. The platform according to claim 15, wherein the source of drilling mud and power is located on a jack up rig adjacent the platform.

17. The platform according to claim 15, wherein one or more further movable decommissioning towers are installed on the platform.