Sensor receiver nulls and null steering

Patent metadata

Field	Value
Publication number	US-2016109596-A1
Application number	US-201514818932-A
Country	US
Kind code	A1
Filing date	Aug 5, 2015
Priority date	Oct 17, 2014
Publication date	Apr 21, 2016
Grant date	—

Abstract

A method. In one embodiment there is provided a method in which a direction from a sensor position to a noise source is determined. A coordinate rotation is applied to a first set of signal values, wherein each signal value of the first set of signal values is based on an output of a corresponding component of a three-component particle motion sensor at the sensor position. The applying generates a rotated set of signal values. The coordinate rotation comprises a coordinate rotation transforming a first set of coordinate axes to a second set of coordinate axes, wherein the first set of coordinate axes has each coordinate axis aligned with a corresponding component of the three-component particle motion sensor at the sensor position, and the second set of coordinate axes comprises a first axis pointed in a direction opposite the direction from the sensor position to the noise source.

First claim

What is claimed is:

1 . A method comprising:
determining a direction from a sensor position to a noise source; applying a coordinate rotation to a first set of signal values, wherein each signal value of the first set of signal values is based on an output of a corresponding component of a three-component particle motion sensor at the sensor position, the applying generating a rotated set of signal values, wherein the coordinate rotation comprises a coordinate rotation transforming a first set of coordinate axes to a second set of coordinate axes, and wherein:
the first set of coordinate axes has each coordinate axis aligned with a corresponding component of the three-component particle motion sensor at the sensor position; and
the second set of coordinate axes comprises a first axis pointed in a direction opposite the direction from the sensor position to the noise source.

2 . The method of claim 1 further comprising summing a signal value in the rotated set of signal values corresponding to the first axis of the second set of coordinate axes with an output signal from a co-located hydrophone at the sensor position, the summing generating a sum output signal.

3 . The method of claim 1 further comprising determining an orientation of the three-component particle motion sensor, wherein the orientation defines the first set of coordinate axes.

4 . The method of claim 2 further comprising scaling the sum output signal based on a difference between an angle of incidence of a seismic acoustic signal reflected from a hydrocarbon bearing reservoir and a direction of maximum sensitivity of a sensor directivity pattern, wherein the direction of maximum sensitivity is opposite the direction from the sensor position to the noise source.

5 . The method of claim 2 further comprising scaling at least one of the output signal from the co-located hydrophone and the rotated set of signal values prior to the summing, wherein the scaling normalizes the magnitude of the rotated set of signal values and the output signal from co-located hydrophone.

6 . The method of claim 5 further comprising filtering the output signal from the co-located hydrophone, the filtering removing an impulse response of the hydrophone.

7 . The method of claim 5 further comprising filtering the second set of values, the filtering removing an impulse response of the three-component particle motion sensor.

8 . The method of claim 2 further comprising producing a geophysical data product from the sum output signal.

9 . The method of claim 8 further comprising recording the geophysical data product on a tangible, non-volatile computer-readable medium suitable for importing onshore.

10 . A method comprising:
applying a coordinate rotation to a first set of signal values, wherein each signal value of the first set of signal values is based on an output of a corresponding component of a three-component particle motion sensor at a sensor position, the applying generating a rotated set of signal values, wherein the coordinate rotation comprises a coordinate rotation transforming a first set of coordinate axes to a second set of coordinate axes, and wherein:
the first set of coordinate axes having each coordinate axis aligned with a corresponding component of the three-component particle motion sensor at the sensor position; and
the second set of coordinate axes comprises a first axis pointed in a direction opposite a direction from the sensor position to a noise source emitting an acoustic noise signal; and
summing a signal value corresponding to the axis in the second coordinate system in the direction opposite the direction of the sensor position to the noise source with an output signal from a co-located hydrophone at the sensor position to generate a directivity null in the direction of the noise source, the summing generating a sum output signal; differencing the signal value corresponding to the axis in the second coordinate system in the direction opposite the direction of the sensor position to the noise source with an output signal from the co-located hydrophone at the sensor position to generate a directivity null opposite the direction of the noise source, the differencing generating a difference output signal; and applying a signal processing operation on the sum signal and the difference signal to remove the attributes of the noise source from the sum output signal.

11 . The method of claim 10 wherein applying the signal processing operation on the sum output signal and the difference output signal comprises cross-correlating the sum output signal and the difference output signal, the signal processing operation generating a recovered signal.

12 . The method of claim 10 further comprising determining the direction from the sensor position to the noise source emitting an acoustic noise signal.

13 . The method of claim 10 further comprising determining an orientation of the three-component particle motion sensor.

14 . The method of claim 10 further comprising producing a geophysical data product from the recovered signal.

15 . The method of claim 14 further comprising performing geophysical analysis onshore on the geophysical data product.

16 . A method comprising:
determining a propagation direction of a surface-reflected seismic acoustic signal; applying a coordinate rotation to a first set of signal values, wherein each signal value of the first set of signal values is based on an output of a corresponding component of a three-component particle motion sensor at the sensor position, the applying generating a rotated set of signal values, wherein the coordinate rotation comprises a coordinate rotation transforming a first set of coordinate axes to a second set of coordinate axes, and wherein:
the first set of coordinate axes has each coordinate axis aligned with a corresponding component of the three-component particle motion sensor; and
the second set of coordinate axes comprises a first axis pointed in a direction opposite the propagation direction of the surface-reflected seismic acoustic signal; and
summing a signal value in the rotated set of signal values corresponding to the first axis of the second set of coordinate axes with an output signal from a hydrophone co-located with the three-component particle motion sensor, the summing generating a sum output signal.

17 . The method of claim 16 further comprising scaling the sum output signal based on a difference between an angle of incidence of a seismic acoustic signal reflected from a hydrocarbon bearing reservoir and a direction of maximum sensitivity of a sensor directivity pattern, wherein the direction of maximum sensitivity is opposite the direction of propagation direction of the surface-reflected seismic acoustic signal.

18 . The method of claim 16 further comprising determining an orientation of the three-component particle motion sensor.

19 . The method of claim 16 further comprising scaling at least one of the output signal from the co-located hydrophone and the second set of values prior to the summing, wherein the scaling normalizes the magnitude of the second set of signals and the output signal from co-located hydrophone.

20 . The method of claim 19 further comprising filtering the output signal from the co-located hydrophone, the filtering removing an impulse response of the hydrophone.

21 . The method of claim 16 further comprising producing a geophysical data product from the sum output signal.

Assignees

• Pgs Geophysical As

Inventors

• Murray Paul Edwin
• Fernihough Robert Alexis Peregrin

Classifications

• G01S5/22 Primary

  Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements (G01S5/28 takes precedence) · CPC title

• G01V1/3808

  Seismic data acquisition, e.g. survey design · CPC title

• G01V1/364 Primary

  Seismic filtering (G01V1/37 takes precedence) · CPC title

• G01V2210/324

  Filtering · CPC title

• G01S15/876 Primary

  Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector (G01S15/872 takes precedence) · CPC title