US2014081577A1PendingUtilityA1

Method For Calibrating Seismic Imaging Velocities

46
Assignee: FAIRFIELD IND INCPriority: Jan 16, 2009Filed: Nov 21, 2013Published: Mar 20, 2014
Est. expiryJan 16, 2029(~2.5 yrs left)· nominal 20-yr term from priority
Inventors:Paul Docherty
G01V 1/28G01V 1/345
46
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Claims

Abstract

A method for adjusting an isotropic depth image based on a mis-tie volume is provided. The method generally includes obtaining an isotropic velocity volume for a geophysical volume, obtaining an isotropic depth image of the geophysical volume, obtaining time-depth pairs at downhole locations in the geophysical volume, generating mis-tie values based on the time-depth pairs and the isotropic velocity volume, assigning uncertainties to the mis-tie values, generating a smoothest mis-tie volume that satisfies a target goodness of fit with the mis-tie values. Adjustment of the isotropic depth image may be achieved based on the mis-tie volume or a calibration velocity obtained from the mis-tie volume.

Claims

exact text as granted — not AI-modified
1 - 20 . (canceled) 
     
     
         21 . A method, comprising:
 obtaining an isotropic depth image of a geophysical volume;   obtaining time-depth pairs at downhole locations in the geophysical volume;   generating, via a computer, mis-tie values as a function of a discrepancy between a depth and a corresponding isotropic depth based on the isotropic depth image;   assigning uncertainties to the mis-tie values; and   generating a mis-tie volume that satisfies a target goodness of fit with the mis-tie values.   
     
     
         22 . The method of  claim 21 , comprising:
 obtaining an isotropic velocity volume for the geophysical volume; and   determining the isotropic depth image based on an isotropic velocity analysis of the isotropic velocity volume.   
     
     
         23 . The method of  claim 22 , comprising:
 generating the mis-tie values based on the time-depth pairs and the isotropic velocity volume.   
     
     
         24 . The method of  claim 21 , comprising:
 obtaining a calibration velocity from the mis-tie volume.   
     
     
         25 . The method of  claim 24 , comprising:
 differentiating the mis-tie volume to obtain the calibration velocity, wherein the calibration velocity is an estimate of a velocity of vertically propagating waves in the geophysical volume.   
     
     
         26 . The method of  claim 21 , comprising:
 adjusting the isotropic depth image using the mis-tie volume.   
     
     
         27 . The method of  claim 21 , comprising:
 generating a time image from the isotropic depth image.   
     
     
         28 . The method of  claim 27 , comprising:
 generating a depth image from the time image.   
     
     
         29 . The method of  claim 29 , wherein the depth image is substantially equivalent to an adjusted isotropic image from the mis-tie volume. 
     
     
         30 . The method of  claim 21 , comprising:
 computing the depth mis-tie values according to the expression:
     m ( x, y, t )= z   iso ( x, y, t )− z ( x, y, t )
 
   
       where z iso (x, y, t) is an isotropic depth based on the isotropic depth image, z(x, y, t) is a depth, and m(x, y, t) is a depth mis-tie. 
     
     
         31 . A computer implemented method comprising:
 obtaining, via a computer, an isotropic depth image of a geophysical volume;   obtaining time-depth pairs at downhole locations in the geophysical volume, the time-depth pairs corresponding to one or more wells located in the geophysical volume based on the data indicative of the at least one measurement;   generating, via the computer, mis-tie values as a function of a discrepancy between a depth and a corresponding isotropic depth based on the isotropic depth image;   assigning uncertainties to the depth mis-tie values;   generating a smoothest mis-tie volume that satisfies a target goodness of fit with the depth mis-tie values;   obtaining a calibration velocity from the mis-tie volume;   generating a time image from the isotropic depth image; and   generating a depth image from the time image using the calibration velocity.   
     
     
         32 . The computer implemented method of  claim 31 , comprising:
 obtaining an isotropic velocity volume for the geophysical volume using data indicative of at least one seismic survey.   
     
     
         33 . The computer implemented method of  claim 31 , comprising:
 adjusting the isotropic depth image using the mis-tie volume.   
     
     
         34 . The computer implemented method of  claim 31 , comprising:
 computing the depth mis-tie values according to the expression:
     m ( x, y, t )= z   iso ( x, y, t )− z ( x, y, t )
 
   
       where z iso (x, y, t) is an isotropic depth based on the isotropic depth image, z(x, y, t) is a depth, and m(x, y, t) is a depth mis-tie. 
     
     
         35 . A computer configured to:
 obtain an isotropic depth image of a geophysical volume;   obtain time-depth pairs at downhole locations in the geophysical volume;   generate mis-tie values as a function of a discrepancy between a depth and a corresponding isotropic depth based on the isotropic depth image;   assign uncertainties to the mis-tie values; and   generate a mis-tie volume that satisfies a target goodness of fit with the mis-tie values.   
     
     
         36 . The computer of  claim 35 , further configured to:
 obtain an isotropic velocity volume for the geophysical volume; and determine the isotropic depth image based on an isotropic velocity analysis of the isotropic velocity volume.   
     
     
         37 . The computer of  claim 36 , further configured to:
 generating the mis-tie values based on the time-depth pairs and the isotropic velocity volume.   
     
     
         38 . The computer of  claim 35 , further configured to:
 obtain an isotropic velocity volume for the geophysical volume using data indicative of at least one seismic survey.   
     
     
         39 . The computer of  claim 35 , further configured to:
 obtain a calibration velocity from the mis-tie volume; and   differentiate the mis-tie volume to obtain the calibration velocity, wherein the calibration velocity is an estimate of the velocity of vertically propagating waves in the geophysical volume.   
     
     
         40 . The computer of  claim 35 , further configured to:
 computing the depth mis-tie values according to the expression:
     m ( x, y, t )= z   iso ( x, y, t )− z ( x, y, t )
 
   
       where z iso (x, y, t) is an isotropic depth based on the isotropic depth image, z(x, y, t) is a depth, and m(x, y, t) is a depth mis-tie.

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