Gravity measurements using seismic streamers

Patent metadata

Field	Value
Publication number	US-9297923-B2
Application number	US-93886610-A
Country	US
Kind code	B2
Filing date	Nov 3, 2010
Priority date	Mar 1, 2010
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A technique facilitates collection and use of data on subterranean formations. The technique comprises obtaining gravity measurements through the use of seismic streamers. At least one streamer is provided such that each streamer has multiple sensors, e.g. accelerometers. The at least one streamer is towed with a tow vessel, and gravity data are accumulated via the multiple sensors during towing.

First claim

What is claimed is:

1. A method of obtaining gravity measurements using seismic streamers, comprising:
providing at least one multi-component streamer, each multi-component streamer having a plurality of sensors;
towing the at least one multi-component streamer with a tow vessel;
accumulating gravity data with the plurality of sensors during towing;
ensemble averaging the gravity data from the plurality of sensors to enhance the precision of the gravity measurements;
processing the gravity data to correct for sensor rotation due to motion of the at least one multi-component streamer during towing; and
determining information related to a subterranean formation based on horizontal gravity gradients determined from the gravity data accumulated with the plurality of sensors.

2. The method as recited in claim 1 , wherein providing comprises providing each multi-component streamer with the plurality of sensors in the form of accelerometers.

3. The method as recited in claim 2 , wherein providing further comprises providing each multi-component streamer with a plurality of pressure sensors.

4. The method as recited in claim 1 , further comprising conducting a seismic

5. The method as recited in claim 4 , wherein conducting the seismic survey comprises collecting seismic data with the plurality of sensors; and wherein determining comprises determining whether a reservoir of hydrocarbons is present.

6. The method as recited in claim 5 , wherein towing further comprises towing seismic sources.

7. The method as recited in claim 6 , wherein accumulating comprises continuously acquiring and storing the gravity data independently of shots fired by the seismic sources; and further comprising independently processing and storing the seismic data.

8. The method as recited in claim 4 , wherein accumulating comprises accumulating gravity data from a low frequency dataset while seismic measurements are obtained from a higher frequency dataset collected from the same plurality of sensors.

9. The method as recited in claim 1 , wherein accumulating comprises accumulating data on horizontal gradients of gravity.

10. The method as recited in claim 1 , further comprising filtering, binning, and averaging the gravity data.

11. A method of conducting a seismic survey, comprising:
towing a plurality of streamers with a tow vessel in which each streamer comprises multiple accelerometers;
collecting seismic data from the multiple accelerometers during towing;
simultaneously collecting gravity data from the multiple accelerometers during towing;
independently processing and storing the seismic data and the gravity data on at least one processing system; and
processing the gravity data to determine gravity gradients which provide information on a subterranean formation.

12. The method as recited in claim 11 , further comprising correcting the gravity data to compensate for environmental parameters; and wherein processing comprises determining horizontal gravity gradients indicating the presence of a reservoir of hydrocarbons.

13. The method as recited in claim 11 , further comprising calibrating the accelerometers at each sensor location by calibrating orthogonal accelerometers.

14. The method as recited in claim 11 , further comprising calibrating the accelerometers by calibrating accelerometers, located at different sensor locations along each streamer, with respect to each other.

15. The method as recited in claim 11 , further comprising enhancing the signal to noise ratio of the gravity data by summing measurements from accelerometers of the multiple accelerometers according to a binning procedure.

16. A system, comprising:
a survey system having at least one streamer with each streamer comprising a plurality of sensors, the survey system further comprising a processing system to process data transferred from the plurality of sensors of each streamer, wherein the processing system processes the data in a manner which provides both seismic information and gravity measurements, the processing system being configured to ensemble average gravity data from the plurality of sensors to enhance the gravity measurements, the processing system comprising at least one filter to correct for environmental parameters and to determine data related to a subterranean formation via horizontal gravity gradients.

17. The system as recited in claim 16 , wherein the plurality of sensors comprises a plurality of accelerometers.

18. The system as recited in claim 17 , wherein the survey system comprises at least one seismic source.

19. The system as recited in claim 16 , wherein the survey system comprises a plurality of streamers; and wherein the data related to the subterranean formation comprises data related to the presence of hydrocarbon deposits.

Assignees

• Muyzert Everhard
• Christie Philip A F
• Goujon Nicolas
• Kragh Julian Edward Ed
• Robertsson Johan O A
• Westerngeco Llc

Inventors

• Muyzert Everhard
• Christie Philip A F
• Goujon Nicolas
• Kragh Julian Edward Ed
• Robertsson Johan O A

Classifications

• G01V7/06

  Analysis or interpretation of gravimetric records · CPC title

• G01V7/00 Primary

  Measuring gravitational fields or waves; Gravimetric prospecting or detecting · CPC title

• G01V2210/6165

  Gravitational · CPC title

• G01V7/16

  specially adapted for use on moving platforms, e.g. ship, aircraft · CPC title