Patent ID: 11880011
Assignee: UNIVERSITY OF HOUSTON SYSTEM
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 3:
4. A method for predicting surface waves in seismic data to facilitate their removal from the seismic data prior to analysis of the seismic data in connection with seismic exploration of subsurface energy sources, comprising:
obtaining and recording input multi-channel seismic data from a plurality of receivers located near a subsurface feature, wherein the input multi-channel seismic data comprises a plurality of recorded seismic traces at a plurality of locations near the receivers;
generating estimated surface wave phase velocities from the input multi-channel seismic data using nonlinear signal comparison (NLSC), wherein the step of generating estimated surface wave phase velocities comprises using the following equation:, S
     NLSC
     ij
    
    (
    
     ω
     ,
     
      
       V
       
        p
        ⁢
        h
       
      
      ;
      σ
     
    
    )
   
   =
   
    
     
      
       S
       NL
       ij
      
      (
      
       ω
       ,
       
        
         V
         
          p
          ⁢
          h
         
        
        (
        ω
        )
       
      
      )
     
     -
     
      
       S
       π
      
      (
      ω
      )
     
    
    
     1
     -
     
      
       S
       π
      
      (
      ω
      )
     
    
   
  
  ,
 

wherein ω is frequency,
Vph(ω) is phase-velocity,
SNLSCij is a normalized dispersion map using ith and jth traces,
σ is a nonnegative parameter to control resolution,
SNLij is an unnormalized dispersion map represented by:, S
     NL
     ij
    
    (
    
     ω
     ,
     
      V
      
       p
       ⁢
       h
      
     
    
    )
   
   =
   
    
     1
     T
    
    ⁢
    
     
      
       ∫
       T
      
      0
     
     
      
       exp
       (
       
        -
        
         
          
           [
           
            
             
              
               d
               _
              
              i
             
             (
             
              t
              ;
              ω
             
             )
            
            -
            
             
              
               d
               _
              
              j
             
             (
             
              
               t
               +
               
                
                 x
                 ij
                
                
                 V
                 ph
                
               
              
              ;
              ω
             
             )
            
           
           ]
          
          2
         
         
          4
          ⁢
          
           ω
           2
          
          ⁢
          
           π
           
            -
            2
           
          
          ⁢
          
           σ
           2
          
         
        
       
       )
      
      ⁢
      dt
     
    
   
  
  ,
 

wherein T is the length of the measured time window,
di and dj are recorded seismic traces normalized by variance and represented as:, d
      _
     
     i
    
    (
    
     t
     ;
     ω
    
    )
   
   -
   
    
     σ
     i
     
      -
      1
     
    
    ⁢
    
     
      d
      i
     
     (
     
      t
      ;
      ω
     
     )
    
   
  
  ,
  
   
    
     
      d
      _
     
     j
    
    (
    
     
      t
      +
      
       
        x
        ij
       
       
        V
        ph
       
      
     
     ;
     ω
    
    )
   
   =
   
    
     σ
     i
     
      -
      1
     
    
    ⁢
    
     
      d
      j
     
     (
     
      
       t
       +
       
        
         x
         ij
        
        
         V
         ph
        
       
      
      ;
      ω
     
     )
    
   
  
  ,
 

wherein σi and σj are variances defined as:, σ
    i
    2
   
   =
   
    
     ∫
     0
     T
    
    
     
      
       d
       i
       2
      
      (
      
       t
       ;
       ω
      
      )
     
     ⁢
     dt
    
   
  
  ,
  
   
    σ
    j
    2
   
   =
   
    
     ∫
     0
     T
    
    
     
      
       d
       j
       2
      
      (
      
       
        t
        +
        
         
          x
          ij
         
         
          V
          ph
         
        
       
       ;
       ω
      
      )
     
     ⁢
     dt
    
   
  
  ,
 

 and
Sπ is a reference value for normalization represented by:

Sπ(ω)=I0(b)e−b,

wherein, b
  =
  
   
    π
    2
   
   
    
     σ
     2
    
    ⁢
    
     ω
     2
    
    ⁢
    T
   
  
 

 and I0 is a modified Bessel function of zero-th order;
generating predicted surface waves for each receiver by using the estimated surface wave phase velocities and performing a phase shift and local stacking analysis for seismic traces at locations near each receiver; and
using the predicted surface waves in connection with analysis of the seismic data to provide information about the subsurface feature, wherein the subsurface feature is an energy source.