Combining seismic data from sensors to attenuate noise

Abstract

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.

What is claimed is: 
     
         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, wherein the divergence sensor includes a container containing a material and a pressure sensor immersed in the material, and wherein a portion of the sensor assembly including the divergence sensor is connected with the ground so that the divergence sensor senses pressure fluctuations in the material resulting at least partially from ground roll;   receiving first data representing the reflected seismic waves from the seismic sensor and second data representing the pressure fluctuations from the divergence sensor, the first data representing measurements along one 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 at 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 . 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, wherein the divergence sensor includes a container containing a material and a pressure sensor immersed in the material, and the divergence sensor is insensitive to a direction of wave propagation, and wherein the sensor assembly including the divergence sensor is connected with the ground so that the divergence sensor senses pressure fluctuations in the material resulting at least partially from ground roll;   wherein the processor is configured to combine first data representing the reflected seismic waves from the seismic sensors with second data representing the pressure fluctuations from the divergence sensors to attenuate ground-roll noise in the first data from the seismic sensors, the first data representing measurements along one or more axes, and the second data comprising measurements insensitive to a direction of wave propagation.   
     
     
         11 . The system of  claim 10 , wherein the material is selected from the group of a liquid, a gel and a solid. 
     
     
         12 . The system of  claim 10 , 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 10 , wherein the controller is configured to communicate over a cable with the sensor assemblies. 
     
     
         15 . The system of  claim 10 , wherein the controller is configured to communicate wirelessly with the sensor assemblies. 
     
     
         16 . The system of  claim 10 , 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 . 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, wherein the divergence sensor includes a container containing a material and a pressure sensor immersed in the material, and the divergence sensor is insensitive to a direction of wave propagation, and wherein a portion of the sensor assembly including the divergence sensor is connected with the ground so that the divergence sensor senses pressure fluctuations resulting at least partially from ground roll; and   combine first data representing the reflected seismic waves from the seismic sensors with second data representing the pressure fluctuations from the divergence sensors to attenuate ground-roll noise in the first data from the seismic sensors, the first data representing measurements along one or more axes, and the second data comprising measurements insensitive to a direction of wave propagation.   
     
     
         19 . The article of  claim 18 , wherein combining the first data and the second data comprises subtracting the second data from the first data. 
     
     
         20 . 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. 
     
     
         21 . The system of  claim 10 , wherein at least one of the sensor assemblies has a housing containing the corresponding seismic sensor and the corresponding divergence sensor. 
     
     
         22 . 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.