Marine seismic surveying

• US 7,066,687 B2
• Filed: 11/17/2004
• Issued: 06/27/2006
• Est. Priority Date: 05/03/2000
• Status: Expired due to Fees

• Current Assignee: James Martin, Johan Fredrik Naes, Nicolas Goujon, Philip Christie, Rune Voldsbekk
• Original Assignee: James Martin, Johan Fredrik Naes, Nicolas Goujon, Philip Christie, Rune Voldsbekk
• Inventors: Christie, Philip, Martin, James, Voldsbekk, Rune, Goujon, Nicolas, Naes, Johan Fredrik
• Primary Examiner(s): LAGMAN, FREDERICK LYNDON
• Application Number:
  US10/990,572
• Publication Number:
  US 20050105392A1
• Time in Patent Office: 587 Days
• Field of Search: 405/157, 405/158, 405159-161, 405/172, 405/166, 405/167, 367/15, 367/20
• US Class Current: 405/160
• CPC Class Codes: G01V 1/38 specially adapted for water-covered areas G01V1/28 takes precedence
• CPC Class Codes: G01V 1/3852 to the seabed
• CPC Class Codes: G01V 2210/1427 Sea bed
• CPC Class Codes: G01V 2210/612 Previously recorded data, e.g. time-lapse or 4D
• CPC Class Codes: H02G 1/10 in or under water

Abstract

A method of performing a seismic survey of a hydrocarbon reservoir in the earth formations beneath a body of water includes deploying a seismic cable from a drum carried by a remotely operated vehicle on the seabed. The cable is deployed into a lined trench, which is formed either concurrently with cable deployment or during a previous survey, to ensure good repeatability of successive surveys of the reservoir, in order to enable changes in characteristics of the reservoir, eg due to depletion, to be monitored.

Claims

1. A method of performing a seismic survey of earth formations beneath a body of water, the method comprising the steps of:

(a) forming a trench in the bottom of the body of water;

(b) lining the trench;

(c) deploying a seismic cable having a plurality of seismic sensors distributed therealong in the lined trench;

(d) operating an acoustic source in the body of water to produce seismic signals which enter the formations; and

(e) detecting seismic signals which return from the formations with said sensors.

2. A method as claimed in claim 1, wherein the trench is lined with a relatively soft, relatively high friction material, such as nylon-reinforced plastic or rubber matting.

3. A method as claimed in claim 2, wherein the material used to line the trench is initially substantially flat, and is provided with fold lines which enable it to be folded into the trench.

4. A method as claimed in claim 3, wherein at least one of the fold lines comprises a line of perforations.

5. A method as claimed in any one of claims 1 to 4, wherein said material incorporates an elongate metal member which after installation of the material in the trench can be used as an elongate locating means.

6. A method as claimed in claim 2, wherein the material used to line the trench is made in pre-formed sections.

7. A method as claimed in claim 6, wherein the pre-formed sections are installed in the trench so as to be substantially acoustically de-coupled from each other.

14. A method as claimed in any one of claims 1 to 4 and 6 to 8 further including blowing debris from the trench immediately prior to laying the seismic cable therein.

8. A method of performing a seismic survey of earth formations beneath a body of water, the method comprising the steps of:

(a) forming a trench in the bottom of the body of water;

(b) lining the trench, wherein the trench is lined with a relatively soft, relatively high friction material, the material made in pre-formed sections, thereby forming a lined trench;

(c) deploying a seismic cable having a plurality of seismic sensors distributed therealong in the lined trench;

(d) operating an acoustic source in the body of water to produce seismic signals which enter the formations; and

(e) detecting seismic signals which return from the formations with said sensors.

9. A method as claimed in claim 8, wherein the pre-formed sections are installed in the trench so as to be substantially acoustically de-coupled from each other.

10. A method as claimed in claim 8, wherein the material used to line the trench is brightly colored, to enhance its visibility at the bottom of the body of water.

11. A method as claimed in claim 8, wherein the trench forming step includes providing the trench with an openable lid.

12. A method as claimed in claim 11, wherein the lid is made from a brightly colored material, to enhance its visibility at the bottom of the body of water.

13. A method as claimed in claim 8 further comprising guiding the seismic cable in to the trench using a guide means in the trench.

15. A method of performing a seismic survey of earth formations beneath a body of water, the method comprising the steps of:

(a) forming a trench in the bottom of the body of water employing an autonomous or remotely operated vehicle at the bottom of the body of water;

(b) lining the trench;

(c) deploying a seismic cable having a plurality of seismic sensors distributed therealong in the lined trench;

(d) operating an acoustic source in the body of water to produce seismic signals which enter the formations; and

(e) detecting seismic signals which return from the formations with said sensors.

16. A method as claimed in claim 15, wherein the trench is lined with a relatively soft, relatively high friction material, such as nylon-reinforced plastic or rubber matting.

17. A method as claimed in claim 16, wherein the material used to line the trench is initially substantially flat, and is provided with fold lines which enable it to be folded into the trench.

18. A method as claimed in claim 17, wherein at least one of the fold lines comprises a line of perforations.

19. A method as claimed in any one of claims 16 to 18, wherein said material incorporates an elongate metal member which after installation of the material in the trench can be used as an elongate locating means.

20. A method as claimed in claim 16, wherein the material used to line the trench is made in pre-formed sections.