Combining seismic data from sensors to attenuate noise
To perform noise attenuation for seismic surveying, a sensor assembly is deployed on a ground surface, where the sensor assembly has a seismic sensor to measure seismic waves propagated through a subterranean structure, and a divergence sensor comprising a pressure sensor to measure noise. First data is received from the seismic sensor, and second data is received from the divergence sensor. The first data and the second data are combined to attenuate noise in the first data.
1. A method of noise attenuation for land-based seismic surveying, comprising:
deploying a sensor assembly at a ground surface, wherein the sensor assembly has a seismic sensor to measure seismic waves reflected from a subterranean structure in response to seismic waves transmitted due to activation of at least one seismic source, and a divergence sensor comprising a pressure sensor to measure ground-roll noise, wherein the divergence sensor includes a container containing a material and the pressure sensor immersed in the material, and the divergence sensor is insensitive to a direction of wave propagation, and wherein the divergence sensor is buried below the ground surface and a portion of the sensor assembly including the divergence sensor is in contact with an earth medium underneath the ground surface;
receiving first data representing the reflected seismic waves from the seismic sensor and second data representing the ground-roll noise from the divergence sensor, the first data representing measurements along two or more axes, and the second data comprising measurements insensitive to a direction of wave propagation; and
combining the first data and the second data to attenuate ground-roll noise in the first data.
2. The method of claim 1 , wherein the seismic sensor and divergence sensor are physically spaced apart by a predetermined distance.
3. The method of claim 1 , wherein combining the first data and the second data comprises subtracting the second data from the first data.
4. The method of claim 3 , wherein subtracting the second data from the first data comprises subtracting a product of the second data and a filter operator from the first data.
5. The method of claim 1 , wherein the material is selected from the group consisting of a liquid, a gel, and a solid.
6. The method of claim 1 , wherein the second data from the divergence sensor provides a better noise model than a component orthogonal to, or near-orthogonal to, the first data from the seismic sensor.
7. The method of claim 1 , further comprising deploying additional sensor assemblies on the ground surface, where each of the additional sensor assemblies has a seismic sensor to measure seismic waves reflected from the subterranean structure, and a divergence sensor to measure noise.
8. The method of claim 7 , wherein deploying the sensor assemblies comprises deploying the sensor assemblies in an environment that includes one or more obstructions that disturbs a regular pattern of the sensor assemblies, wherein provision of the divergence sensors enable noise attenuation even without the regular pattern of the sensor assemblies.
9. The method of claim 8 , wherein deploying the sensor assemblies comprises providing sensor assemblies that are spaced apart from each other by a distance larger than half a shortest wavelength of noise recorded by the divergence sensors.
10. The method of claim 1 , wherein deploying the sensor assembly comprises deploying the sensor assembly having a housing containing the seismic sensor and the divergence sensor.
11. A system comprising:
a controller having a processor to receive data collected by sensor assemblies deployed at a ground surface, where each of the sensor assemblies has a seismic sensor to measure seismic waves reflected from a subterranean structure, and a divergence sensor comprising a pressure sensor to measure ground-roll noise, wherein the divergence sensor includes a container containing a material and the pressure sensor immersed in the material, and the divergence sensor is insensitive to a direction of wave propagation, and wherein the divergence sensor is buried below the ground surface and a portion of the sensor assembly including the divergence sensor is in contact with an earth medium underneath the ground surface,
wherein the processor is configured to combine first data representing the reflected seismic waves from the seismic sensors with second data representing the ground-roll noise from the divergence sensors to attenuate ground-roll noise in the first data from the seismic sensors, the first data representing measurements along two or more axes, and the second data comprising measurements insensitive to a direction of wave propagation.
12. The system of claim 11 , wherein the material is selected from the group of a liquid, a gel, and a solid.
13. The system of claim 11 , wherein, in each of the sensor assemblies, the seismic sensor is provided above and external to the container of the divergence sensor.
14. The system of claim 11 , wherein the controller is configured to communicate over a cable with the sensor assemblies.
15. The system of claim 11 , wherein the controller is configured to communicate wirelessly with the sensor assemblies.
16. The system of claim 11 , wherein combining the first data and the second data comprises subtracting the second data from the first data.
17. The system of claim 16 , wherein subtracting the second data from the first data comprises subtracting a product of the second data and a filter operator from the first data.
18. The system of claim 11 , wherein at least one of the sensor assemblies has a housing containing the corresponding seismic sensor and the corresponding divergence sensor.
19. An article comprising at least one non-transitory computer-readable storage medium containing instructions that upon execution cause a system having a processor to:
receive data collected by sensor assemblies arranged at a ground surface, where each of the sensor assemblies has a seismic sensor to measure seismic waves reflected from a subterranean structure, and a divergence sensor comprising a pressure sensor to measure ground-roll noise, wherein the divergence sensor includes a container containing a material and the pressure sensor immersed in the material, and the divergence sensor is insensitive to a direction of wave propagation, and wherein the divergence sensor is buried below the ground surface and a portion of the sensor assembly including the divergence sensor is in contact with an earth medium underneath the ground surface; and
combine first data representing the reflected seismic waves from the seismic sensors with second data representing the ground-roll noise from the divergence sensors to attenuate ground-roll noise in the first data from the seismic sensors, the first data representing measurements along two or more axes, and the second data comprising measurements insensitive to a direction of wave propagation.
20. The article of claim 19 , wherein combining the first data and the second data comprises subtracting the second data from the first data.
21. The article of claim 19 , wherein at least one of the sensor assemblies has a housing containing the corresponding seismic sensor and the corresponding divergence sensor.