Determining An Orientation Angle of A Survey Sensor

Abstract

Measurement data acquired by at least one sensor in a cable structure towed through a body of water is received. A torsional vibration noise component in the measurement data is estimated. The torsional vibration noise component is used to estimate a rotation angle of the at least one survey sensor with respect to a reference coordinate system of the cable structure.

What is claimed is: 
     
         1 . A system comprising:
 a storage medium to store measurement data acquired by at least one survey sensor in a subterranean survey operation, wherein the at least one survey sensor is in a cable structure for towing through a body of water; and   at least one processor to:
 estimate a torsional vibration noise component in the measurement data; and 
 use the torsional vibration noise component to estimate a rotation angle of the at least one survey sensor with respect to a reference coordinate system of the cable structure. 
   
     
     
         2 . The system of  claim 1 , wherein the at least one processor is to further rotate the measurement data based on the estimated rotation angle. 
     
     
         3 . The system of  claim 1 , wherein the estimating of the rotation angle is achieved by using Kalman filtering. 
     
     
         4 . The system of  claim 1 , wherein the at least one processor is to further:
 compute a particular angle component of the rotation angle using the torsional vibration noise component, where the rotation angle is composed of the particular angle component and a second angle component that varies at a rate slower than the particular angle component.   
     
     
         5 . The system of  claim 4 , wherein the at least one processor is to further:
 apply a filter to remove components of the measurement data in a predefined wavenumber range to allow computing of the particular angle component.   
     
     
         6 . The system of  claim 4 , wherein the at least one processor is to further:
 compute the second angle component based on applying a low-pass filter having a predefined cutoff frequency.   
     
     
         7 . The system of  claim 1 , wherein the measurement data is collected from multiple survey sensors in the cable structure, and wherein at least two of the multiple survey sensors are provided on different sides of a center axis of the cable structure. 
     
     
         8 . An article comprising at least one machine-readable storage medium storing instructions that upon execution cause a system to:
 receive measurement data acquired by at least one sensor in a cable structure towed through a body of water;   estimate a torsional vibration noise component in the measurement data; and   use the torsional vibration noise component to estimate a rotation angle of the at least one survey sensor with respect to a reference coordinate system of the cable structure.   
     
     
         9 . The article of  claim 8 , wherein the instructions upon execution cause the system to further rotate the measurement data based on the rotation angle. 
     
     
         10 . The article of  claim 8 , wherein the rotation angle is composed of a first angle component and a second angle component that varies at a rate faster than the first angle component, wherein the instructions upon execution cause the system to further:
 compute the second angle component based on the torsional vibration noise.