SENSOR ASSEMBLY HAVING A SEISMIC SENSOR, PRESSURE SENSOR, AND PROCESSOR TO APPLY FIRST AND SECOND DIGITAL FILTERS

• US 20110085419A1
• Filed: 04/09/2010
• Published: 04/14/2011
• Est. Priority Date: 10/12/2009
• Status: Active Grant

• Current Assignee: WesternGeco LLC (Schlumberger NV)
• Original Assignee: WesternGeco LLC (Schlumberger NV)
• Inventors: Liu, Qinglin, Soerli, Jon Magnus, Ronnow, Daniel, Kragh, Julian Edward, Edme, Pascal, Muyzert, Everhard
• Granted Patent: US 8,520,469 B2
• Time in Patent Office: Days
• US Class Current: 367/43
• CPC Class Codes: G01V 1/364 Seismic filtering G01V1/37 takes precedence

Abstract

A sensor assembly includes a housing structure, a seismic sensor in the housing structure to measure seismic waves propagated through a subterranean structure, and a pressure sensor in the housing structure. A processor in the housing structure is configured to receive a first signal based on an output of the seismic sensor, and a second signal based on an output of the pressure sensor. First and second digital filters are applied to the first and second signals. Application of the first and second digital filters to the first and second signals causes production of a substantially zero output in response to input that includes just noise data detected at the seismic sensor and the pressure sensor.

Claims

1. A sensor assembly comprising:

a housing structure;

a seismic sensor in the housing structure to measure seismic waves propagated through a subterranean structure;

a pressure sensor in the housing structure; and

a processor in the housing structure configured to;

receive a first signal based on an output of the seismic sensor, and a second signal based on an output of the pressure sensor;

apply a first digital filter to the first signal;

apply a second digital filter to the second signal,

wherein application of the first digital filter and second digital filter is to cause production of a substantially zero output by the processor in response to input that includes just noise data detected at the seismic sensor and the pressure sensor.

2. The sensor assembly of claim 1, wherein the first signal is represented as s_g, the second signal is represented as s_h, the first digital filter is represented as F_g, and the second filter is represented as F_h, and wherein the processor is configured to produce an output signal s_out=F_g[s_g]+F_h[s_h].

3. The sensor assembly of claim 2, wherein the processor is selected from the group consisting of a digital signal processor (DSP), a programmable gate array, and an integrated circuit device.

4. The sensor assembly of claim 1, further comprising:

a first analog-to-digital converter between the seismic sensor and the processor; and

a second analog-to-digital converter between the pressure sensor and the processor.

5. The sensor assembly of claim 1, wherein the housing structure includes separate housings for the seismic sensor and pressure sensor, respectively.

6. The sensor assembly of claim 1, wherein the seismic sensor is selected from the group consisting of a geophone, an accelerometer, an optical sensor, a velocity sensor, and a motion sensor.

7. The sensor assembly of claim 1, wherein the pressure sensor is selected from the group assembly of a hydrophone and a piezo-electric transducer.

8. The sensor assembly of claim 1, wherein the processor is configured to output a signal that is a combination of an output of the first digital filter and an output of the second digital filter, wherein the output signal is to be sent to a remote controller for recording.

9. The sensor assembly of claim 1, wherein the processor is configured to output plural signals corresponding to outputs of the first and second digital filters, wherein the plural output signals are to be sent to a remote controller for recording.

10. The sensor assembly of claim 1, further comprising a first analog matching filter connected to an output of the seismic sensor, and a second analog matching filter connected to an output of the pressure sensor, wherein the first and second matching filters are configured to produce outputs from which the first and second signals are respectively based.

11. The sensor assembly of claim 1, further comprising a storage medium to store a collection of digital filters, wherein the processor is configured to select the first digital filter from among multiple digital filters in the collection, and to select the second digital filter from among multiple digital filters in the collection, and wherein selecting the first and second digital filters is according to one or more criteria.

12. The sensor assembly of claim 11, wherein the one or more criteria comprise one or more selected from the group consisting of ground surface condition, temperature condition, and type of seismic source.

13. The sensor assembly of claim 1, wherein the processor is configured to dynamically determine the first and second filters based on measured signals by the sensor assembly, wherein dynamically determining the first and second filters comprises:

positioning seismic sources at predetermined positions relative to a spread including the sensor assembly;

recording signals from seismic sensors and pressure sensors in the spread;

selecting a part of each of the recorded signals that is due to noise; and

identifying matching filters for the sensor assembly.

14. The sensor assembly of claim 1, further comprising one or more of a temperature sensor and tilt meter, wherein the processor is configured to use measurements of the one or more of the temperature sensor and tilt meter to adjust a respective transfer function of one or both of the first and second digital filters.

16. The system of claim 1, wherein the processor is configured to output a signal that is a combination of corresponding outputs of the digital filters, the system further comprising:

a controller configured to receive the output signal over the communications medium.

17. The system of claim 16, wherein a first of the signal is represented as s_g, a second of the signals is represented as s_h, a first of the digital filters is represented as F_g, and a second of the digital filters is represented as F_h, and wherein the processor is configured to produce the output signal s_out=F_g[s_g]+F_h[s_h].

15. A system comprising:

a communications medium;

a plurality of sensor assemblies communicatively coupled to the communications medium, wherein at least one of the plurality of sensor assemblies comprises;

a housing structure;

a seismic sensor in the housing structure to measure seismic waves propagated through a subterranean structure;

a pressure sensor in the housing structure; and

a processor in the housing structure configured to;

receive signals based on corresponding outputs of the seismic sensor and pressure sensor;

apply digital filters to respective ones of the signals;

wherein application of the digital filters is to cause production of a substantially zero output by the processor in response to input that includes just noise data detected at the seismic sensor and the pressure sensor.

18. The system of claim 15, wherein the at least one sensor assembly further comprises a storage medium to store a collection of digital filters, wherein the processor is configured to select a first of the digital filters from among multiple digital filters in the collection, and to select a second of the digital filters from among multiple digital filters in the collection, wherein selecting the first and second digital filters is according to one or more criteria, and

wherein the processor is configured to apply the first digital filter to a first signal based on output of the seismic sensor, and to apply the second digital filter to a second signal based on output of the pressure sensor.

19. The system of claim 15, wherein the at least one sensor assembly further comprises a container within the housing structure, wherein the container contains a material, wherein the pressure sensor is immersed in the material, and wherein the material is selected from the group consisting of a liquid, a gel, and a solid.

20. A method comprising:

deploying a plurality of sensor assemblies communicatively coupled to a communications medium, wherein at least one of the plurality of sensor assemblies comprises;

a housing structure;

a seismic sensor in the housing structure to measure seismic waves propagated through a subterranean structure;

a pressure sensor in the housing structure; and

a processor in the housing structure configured to;

receive signals based on corresponding outputs of the seismic sensor and pressure sensor;

apply digital filters to respective ones of the signals;

wherein application of the digital filters is to cause production of a substantially zero output by the processor in response to input that includes just noise data detected at the seismic sensor and the pressure sensor; and

receiving, at a controller over the communications medium, an output signal that is based on the application of the digital filters to the signals.