Rotational Motion Compensated Seabed Seismic Sensors and Methods of use in Seabed Seismic Data Acquisition

• US 20100103770A1
• Filed: 10/22/2009
• Published: 04/29/2010
• Est. Priority Date: 04/08/2005
• Status: Active Grant

• Current Assignee: Reflection Marine Norge AS
• Original Assignee: WesternGeco LLC
• Inventors: De Kok, Robbert J., Melbø, Aslaug H. S., Combee, Leendert, Goujon, Nicolas
• Granted Patent: US 8,351,298 B2
• Time in Patent Office: Days
• US Class Current: 367/15
• CPC Class Codes: G01V 1/16 Receiving elements for seismic signals; Arrangements or adaptations of receiving elements
• CPC Class Codes: G01V 1/184 Multi-component geophones
• CPC Class Codes: G01V 1/36 Effecting static or dynamic corrections on records, e.g. correcting spread; Correlating seismic signals; Eliminating effects of unwanted energy
• CPC Class Codes: G01V 1/38 specially adapted for water-covered areas G01V1/28 takes precedence

Abstract

Apparatus and methods for acquiring seismic data using a seabed seismic data cable positioned on a seabed are described, including correcting for the effect of one or more sensor non-linear motions, which improves accuracy of seismic data. One or multiple non-linear movements of the sensor may be corrected for. It is emphasized that this abstract is provided to comply with the rules requiring an abstract, which will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. 37 CFR 1.72(b).

Claims

1-10. -10. (canceled)

11. A method comprising:

a) acquiring seismic data using a seismic sensor;

b) sensing one or more non-linear motions of the seismic sensor; and

c) correcting the seismic data for the non-linear motion of the seismic sensor.

13. The method of claim 11 wherein sensing the one or more non-linear motions of the seismic sensor comprises sensing non-linear motion;

and wherein correcting the seismic data comprises resolving non-linear movement of the sensor about a substantially horizontal axis into vertical and horizontal components.

14. The method of claim 11 further comprising modeling non-linear motion of the sensor under expected environmental conditions including a non-flat seabed, storing modeled sensor non-linear motion data, and using the data in quality control methods, correcting measured seismic data, or combinations thereof.

21. The method of claim 11, wherein sensing the non-linear motion of the seismic sensor comprises converting horizontal motion of the Earth into non-linear motion of the seismic sensor, thereby reducing the horizontal motion at the sensor location with respect to the motion at the Earth-to-sensor-contact.

22. The method of claim 11, wherein the seismic sensor is an angular velocity sensor, a velocity sensor, an angular motion sensor, or an angular accelerometer.

23. The method of claim 11, wherein the seismic sensor is disposed on a cable lying on a seabed.

24. The method of claim 11, wherein the seismic sensor is disposed on a streamer.

25. The method of claim 11, wherein the seismic sensor is disposed inside the earth.

12. (canceled)

15. A method comprising:

a) acquiring seismic data using a seismic sensor;

b) allowing the sensor to non-linearly move about an axis of the sensor at will;

c) sensing one or more non-linear motions of the sensor; and

d) correcting the seismic data for the non-linear motion of the sensor.

17. The method of claim 15 wherein sensing the non-linear motions of the sensor comprises:

sensing non-linear motion, and

converting horizontal motion of the Earth into non-linear motion of the sensor, thereby reducing the horizontal motion at the sensor location with respect to the motion at the Earth-to-sensor-contact.

19. The method of claim 15 wherein correcting the seismic data comprises resolving non-linear motion of the sensor about a substantially horizontal axis into vertical and horizontal components.

20. The method of claim 15 further comprising:

modeling non-linear motion of the sensor under expected environmental conditions including a non-flat seabed,

storing modeled sensor non-linear motion data, and

using the data during quality control methods, correcting measured seismic data, or combinations thereof.

16. (canceled)

18. (canceled)

26. An apparatus comprising:

a plurality of seismic sensors, each sensor comprising;

a first linear motion seismic sensing unit configured to measure a linear motion along a first axis;

a second linear motion seismic sensing unit configured to measure a linear motion along a second axis that is perpendicular to the first axis; and

one or more non-linear motion sensors configured to measure rotational motions of the sensor about an axis centrally disposed along the line.

27. The apparatus of claim 26, wherein the non-linear motion sensors are configured to resolve the rotational motions of the sensor about the axis into vertical and horizontal components.

28. The apparatus of claim 26, wherein the non-linear motion sensors comprise angular velocity sensors.

29. The apparatus of claim 26, wherein the seismic sensors are disposed on land.

30. The apparatus of claim 26, wherein the seismic sensors are disposed under water.

31. The apparatus of claim 26, further comprising a seismic sensor rotational motion database comprising modeled sensor rotational motion data, measured sensor rotational motion data, or both, wherein one or both of the modeled and measured sensor rotational motion data is collected for non-flat surface conditions.

32. The apparatus of claim 31, further comprising a calculation unit configured to fit the modeled sensor rotational motion data to the measured sensor rotational motion data when the sensor is in a non-flat surface.

33. The apparatus of claim 26, wherein the non-linear motion sensors are configured to measure a horizontal displacement at a circumference of the sensor.

34. An apparatus comprising:

a plurality of seismic sensors spaced along a line, each sensor comprising;

at least one linear motion seismic sensing unit; and

one or more angular velocity sensors for sensing rotational motions of the at least one linear motion sensing unit about an axis centrally disposed along the line, wherein the angular velocity sensors are configured to resolve rotational motions of the at least one linear motion sensing unit about the axis into a horizontal displacement at a circumference of the sensor.

35. The apparatus of claim 34, wherein the angular velocity sensors are configured to resolve a lateral component of the at least one linear motion sensing unit by adding a lateral acceleration of the at least one linear motion sensing unit to a product of an angular acceleration received from one of the angular velocity sensors, and a radius of the sensor.

36. An apparatus comprising:

a plurality of seismic sensors spaced along a line, each sensor comprising;

a first linear motion sensing unit positioned at a center of the sensor;

a second linear motion sensing unit positioned in a first orthogonal position with respect to the first linear motion sensing unit at the center of the sensor;

a third linear motion sensing unit positioned in a second orthogonal position with respect to the first linear motion sensing unit and the second linear motion sensing unit at the center of the sensor; and

a fourth linear motion sensing unit positioned away from the center of the sensor, wherein the first linear motion sensing unit, the second linear motion sensing unit, the third linear motion sensing unit, and the fourth linear motion sensing unit are configured to determine a rotational motion of the sensor.

37. The apparatus of claim 36, further comprising:

a calculation unit configured to determine the rotational motion of the sensor by;

predicting a translation movement of the fourth linear motion sensing unit; and

determining a difference between the predicted translation movement of the fourth linear motion sensing unit and a measured signal of the fourth linear motion sensing unit.

38. The apparatus of claim 37, wherein the translation movement is predicted by decomposing a measured signal of the first linear motion sensing unit, a measured signal of the second linear motion sensing unit, and a measured signal of the third linear motion sensing unit along an axis of the fourth linear motion sensing unit.

39. An apparatus comprising:

a plurality of seismic sensors spaced along a line, each sensor comprising;

a first linear motion sensing unit positioned at a center of the sensor;

a second linear motion sensing unit positioned perpendicularly to the first linear motion sensing unit at the center of the sensor;

a third linear motion sensing unit positioned away from the center of the sensor; and

a calculation unit configured to determine the rotational motion of the sensor by;

predicting a translation movement of the third linear motion sensing unit; and

determining a difference between the predicted translation movement of the third linear motion sensing unit and a measured signal of the third linear motion sensing unit.

40. The apparatus of claim 39, wherein the translation movement is predicted by decomposing a measured signal of the first linear motion sensing unit and a measured signal of the second linear motion sensing unit along an axis of the third linear motion sensing unit.