Patent ID: 11933928
Assignee: INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCES
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. An irregular seismic data collection method based on forward modeling, comprising the following steps:
S1: fully collecting geological information of a work area to build a geological model:
collecting previous geological and geophysical exploration data, obtaining underground information of the work area such as formation velocity, geological structure, anisotropy, and absorption attenuation by using logging data and gravity, magnetic, electrical, and seismic data, and building a high-precision geological model to guarantee accuracy of subsequent forward modeling of seismic data;
S2: determining arrangement parameters of receiver points and shot points for regular high-density collection and irregular sparse collection:
determining arrangement ranges and quantities of the receiver points and the shot points for regular high-density collection, and arrangement ranges, disturbance ranges, quantities, numbers of grids and spacing between the grids of the receiver points and the shot points for irregular sparse collection, and using all the grids as candidate excitation points or sampling points;
S3: performing irregular optimization design on positions of the shot points based on forward modeling:
performing the irregular optimization design on the positions of the shot points based on a high-precision seismic forward modeling technology by using a greedy strategy, to decompose a global optimization problem of arrangement of the shot points into local optimization problems of single shot points, wherein specific steps are as follows:
S301: arranging a receiver point in a center of the arrangement range of the receiver points;
S302: arranging regular high-density shot points in the arrangement range of the shot points, obtaining a regular high-density common receiver point gather D1crp by using the forward modeling technology, and computing a frequency-wavenumber spectrum FK1crp corresponding to the D1crp;
due to regular distribution of temporal sampling points and spatial sampling points of the common receiver point gather corresponding to distribution of the regular high-density shot points, performing discrete uniform Fourier transform on a spatial direction of the D1crp according to the following formula to obtain time-wavenumber domain data TK1crp:, T
   ⁢
   K
   ⁢
   
    1
    crp
   
   ⁢
   
    (
    
     t
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     n
     =
     1
    
    
     N
     -
     1
    
   
   ⁢
   D
   ⁢
   
    1
    crp
   
   ⁢
   
    (
    
     t
     ,
     
      n
      ⁢
      Δ
      ⁢
      x
     
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     k
     ⁢
     n
     ⁢
     Δ
     ⁢
     x
    
   
   ⁢
   Δ
   ⁢
   x
  
 

wherein N is a dimension in the spatial direction, t is time, nΔx is a spatial position of an nth sampling point, Δx is a spatial sampling spacing, k is wavenumber; then performing discrete uniform Fourier transform on a temporal direction of the time-wavenumber domain data TK1crp according to the following formula to obtain the frequency-wavenumber domain data FK1crp:, F
   ⁢
   K
   ⁢
   
    1
    crp
   
   ⁢
   
    (
    
     f
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     m
     =
     1
    
    
     M
     -
     1
    
   
   ⁢
   T
   ⁢
   K
   ⁢
   
    1
    crp
   
   ⁢
   
    (
    
     
      m
      ⁢
      Δt
     
     ,
     k
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     f
     ⁢
     m
     ⁢
     Δ
     ⁢
     t
    
   
   ⁢
   Δ
   ⁢
   t
  
 

wherein M is a dimension in the temporal direction and f is frequency;
S303: arranging the shot points uniformly in the arrangement range of the shot points according to a set quantity of irregular sparse collection shot points, enabling each shot point to traverse all candidate grids in the disturbance range of the shot points in turn, obtaining a common receiver point gather D2crp corresponding to current distribution of the shot points in each disturbance by using the forward modeling technology, and computing a frequency-wavenumber spectrum FK2crp corresponding to the D2crp, wherein specific steps are as follows:
due to uniform temporal sampling points and non-uniform spatial sampling points of the common receiver point gather D2crp obtained by the forward modeling of irregular distribution of the shot points, performing discrete non-uniform Fourier transform on a spatial direction of the D2crp according to the following formula to obtain time-wavenumber domain data TK2crp:, T
   ⁢
   K
   ⁢
   
    2
    crp
   
   ⁢
   
    (
    
     t
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
      
     
      n
      =
      0
     
    
    
     N
     -
     1
    
   
   ⁢
   D
   ⁢
   
    2
    crp
   
   ⁢
   
    (
    
     t
     ,
     
      x
      n
     
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     k
     ⁢
     
      x
      n
     
    
   
   ⁢
   Δ
   ⁢
   
    x
    n
   
  
 

wherein, Δ
    ⁢
    
     x
     n
    
   
   =
   
    
     
      x
      
       n
       +
       1
      
     
     -
     
      x
      
       n
       -
       1
      
     
    
    2
   
  
  ,, and N is a dimension in the spatial direction, k is the wavenumber, and x n is a spatial position of a non-uniform sampling point then performing discrete uniform Fourier transform on a temporal direction of the time-wavenumber domain data TK2crp according to the following formula to obtain frequency-wavenumber domain data FK2crp:, F
   ⁢
   K
   ⁢
   
    2
    crp
   
   ⁢
   
    (
    
     f
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     m
     =
     1
    
    
     M
     -
     1
    
   
   ⁢
   T
   ⁢
   K
   ⁢
   
    2
    crp
   
   ⁢
   
    (
    
     
      m
      ⁢
      Δt
     
     ,
     k
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     f
     ⁢
     m
     ⁢
     Δ
     ⁢
     t
    
   
   ⁢
   Δ
   ⁢
   t
  
 

wherein M is a dimension in the temporal direction;
using a grid corresponding to a minimum error σcrp of the frequency-wavenumber spectrum FK1crp in S302 as an arrangement position of the shot point, wherein the error σcrp is computed according to the following formula:, σ
   crp
  
  =
  
   
    
     ∑
      
    
    
     i
     =
     1
    
    p
   
   ⁢
   
    
     ∑
      
    
    
     j
     =
     1
    
    
     q
     =
     1
    
   
   ⁢
   
    
     (
     
      
       FK
       ⁢
       
        1
        crp
       
       ⁢
       
        (
        
         i
         ,
         j
        
        )
       
      
      -
      
       F
       ⁢
       K
       ⁢
       
        2
        
         c
         ⁢
         r
         ⁢
         p
        
       
       ⁢
       
        (
        
         i
         ,
         j
        
        )
       
      
     
     )
    
    2
   
  
 

wherein p and q are dimensions in a frequency direction and a wavenumber direction of the frequency-wavenumber spectrum and i and j are serial numbers of a data point in the frequency direction and the wavenumber direction of the frequency-wavenumber spectrum, respectively; stopping the disturbances of the shot points when the error cannot be decreased by disturbing any shot point; and
S304: outputting preferred irregular arrangement positions of the shot points;
S4: performing irregular optimization design on positions of the receiver points based on forward modeling:
performing the irregular optimization design on the positions of the receiver points based on the high-precision seismic forward modeling technology by using the greedy strategy, to decompose a global optimization problem of arrangement of the receiver points into local optimization problems of single receiver points, wherein specific steps are as follows:
S401: arranging the shot points in the work area according to the irregular positions of the shot points in S3;
S402: arranging regular high-density receiver points in the arrangement range of the receiver points in the work area, and performing forward modeling for each shot point to obtain a common shot point gather D1csp(s), wherein s is a serial number of the shot point; and computing a frequency-wavenumber spectrum FK1csp(s) corresponding to each common shot point gather;
due to regular distribution of temporal sampling points and spatial sampling points of the common shot point gather corresponding to distribution of the regular high-density receiver points, performing discrete uniform Fourier transform on a spatial direction of the D1csp(s) according to the following formula to obtain time-wave number domain data TK1csp(s):, T
   ⁢
   K
   ⁢
   
    1
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     t
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     n
     =
     0
    
    
     N
     -
     1
    
   
   ⁢
   D
   ⁢
   
    1
    
     c
     ⁢
     
      sp
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     t
     ,
     
      x
      n
     
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     k
     ⁢
     
      x
      n
     
    
   
   ⁢
   Δ
   ⁢
   
    x
    n
   
  
 

wherein the t is a sequence of the temporal sampling points, the k is a wavenumber, and the x is an arrangement position of a spatial sampling point;
then performing discrete uniform Fourier transform on a temporal direction of the time-wavenumber domain data TK1csp(s) according to the following formula to obtain frequency-wavenumber domain data FK1csp(s):, F
   ⁢
   K
   ⁢
   
    1
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     f
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     m
     =
     1
    
    
     M
     -
     1
    
   
   ⁢
   TK
   ⁢
   
    1
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     
      m
      ⁢
      Δt
     
     ,
     k
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     f
     ⁢
     m
     ⁢
     Δ
     ⁢
     t
    
   
   ⁢
   Δ
   ⁢
   t
  
 

S403: arranging the receiver points uniformly in the arrangement range of the receiver points according to a set quantity of irregular sparse collection receiver points, enabling each receiver point to traverse all candidate grids in the disturbance range of the receiver points in turn, and obtaining a common shot point gather D2csp(s) corresponding to all the shot points under the distribution of the irregular sparse collection receiver points by forward modeling for each transform of the positions of the receiver points, wherein s is a serial number of a shot point; and computing a frequency-wavenumber spectrum FK2csp(s) corresponding to the D2csp(s), wherein s is the serial number of the shot point, wherein specific steps are as follows:
due to uniform temporal sampling points and non-uniform spatial sampling points of the common shot point gather D2csp(s) obtained by forward modeling the irregular distribution of the receiver points, performing discrete non-uniform Fourier transform on a spatial direction of the D2csp(s) according to the following formula to obtain time-wavenumber domain data TK2csp(s):, T
   ⁢
   K
   ⁢
   
    2
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     t
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     n
     =
     0
    
    
     N
     -
     1
    
   
   ⁢
   D
   ⁢
   
    2
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     t
     ,
     
      x
      n
     
    
    )
   
   ⁢
   
    e
    
     j
     ⁢
     k
     ⁢
     
      x
      n
     
    
   
   ⁢
   Δ
   ⁢
   
    x
    n
   
  
 

wherein, Δ
    ⁢
    
     x
     n
    
   
   =
   
    
     
      x
      
       n
       +
       1
      
     
     -
     
      x
      
       n
       -
       1
      
     
    
    2
   
  
  ;, then performing discrete uniform Fourier transform on a temporal direction of the time-wavenumber domain data TK2csp(s) according to the following formula to obtain frequency-wavenumber domain data FK2csp(s):, F
   ⁢
   K
   ⁢
   
    2
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     f
     ,
     k
    
    )
   
  
  =
  
   
    
     ∑
      
    
    
     m
     =
     1
    
    
     M
     -
     1
    
   
   ⁢
   T
   ⁢
   K
   ⁢
   
    2
    
     c
     ⁢
     s
     ⁢
     
      p
      ⁡
      (
      s
      )
     
    
   
   ⁢
   
    (
    
     
      m
      ⁢
      Δ
      ⁢
      t
     
     ,
     k
    
    )
   
   ⁢
   
    e
    
     jfm
     ⁢
     Δ
     ⁢
     t
    
   
   ⁢
   Δ
   ⁢
   t
  
 

computing an average value σcsp of frequency-wavenumber spectrum errors of the regular high-density common shot point gathers and the irregular sparse common shot point gathers of all the shot points according to the following formula:, σ
   
    c
    ⁢
    s
    ⁢
    p
   
  
  =
  
   
    1
    S
   
   ⁢
   
    
     ∑
      
    
    
     s
     =
     1
    
    S
   
   ⁢
   
    
     ∑
      
    
    
     i
     =
     1
    
    p
   
   ⁢
   
    
     ∑
      
    
    
     j
     =
     1
    
    q
   
   ⁢
   
    
     (
     
      
       F
       ⁢
       K
       ⁢
       
        1
        
         c
         ⁢
         s
         ⁢
         
          p
          ⁡
          (
          s
          )
         
        
       
       ⁢
       
        (
        
         i
         ,
         j
        
        )
       
      
      -
      
       F
       ⁢
       K
       ⁢
       
        2
        
         c
         ⁢
         s
         ⁢
         
          p
          ⁡
          (
          s
          )
         
        
       
       ⁢
       
        (
        
         i
         ,
         j
        
        )
       
      
     
     )
    
    2
   
  
 

wherein S is a total number of the shot points, and p and q are dimensions in the frequency direction and the wavenumber direction of the frequency-wavenumber spectrum, respectively; using the grid corresponding to a minimum average value as an arrangement position of the receiver point; and stopping the disturbances of the receiver points when the average value of the frequency-wavenumber spectrum errors of the regular high-density common shot point gathers and the irregular sparse common shot point gathers of all the shot points cannot be decreased; and
S404: outputting preferred irregular arrangement positions of the receiver points; and
S5: outputting a preferred irregular sparse observation system:
combining the irregular arrangement positions of the shot points output in S3 and the irregular arrangement positions of the receiver points output in S4 to obtain the irregular sparse observation system comprising the arrangement parameters of the receiver points and the shot points.