Digital core workflow method using digital core image

Abstract

A method for registration and correction of downhole core depth information using digital core images. Digital core images are employed during depth registration, with top and base depths for a selected interval being determined by field data and a digital ruler which calculates an actual interval length based on the digital core image. Correction of the top and base depths is enabled by side-by-side display of the digital core image interval and corresponding well logging data, which displayed information can be manipulated by a user to provide more accurate depth information. The method further allows for shale volume calculations and facies interpretation, again employing the digital core images.

1 . A method for registration of downhole core depth information comprising the steps of: 
 a. providing at least one digital image of a core sample from a well;    b. displaying the at least one digital image on a display device;    c. selecting a displayed interval from the displayed at least one digital image, the displayed interval being defined by a first depth and a second depth spaced from the first depth;    d. establishing an approximate actual depth value for the first depth of the displayed interval; and    e. measuring the length of the displayed interval to determine an approximate actual depth value for the second depth of the displayed interval.    
   
   
       2 . A method for registration and correction of downhole core depth information comprising the steps of: 
 a. providing at least one digital image of a core sample from a well;    b. providing well logging data corresponding to the core sample;    c. displaying the at least one digital image on a display device;    d. selecting a displayed interval from the displayed at least one digital image, the displayed interval being defined by a first depth and a second depth spaced from the first depth;    e. establishing an approximate actual depth value for the first depth of the displayed interval;    f. measuring the length of the displayed interval to determine an approximate actual depth value for the second depth of the displayed interval;    g. displaying the well logging data adjacent the displayed interval;    h. allowing for comparison of the well logging data and the displayed interval; and    i. allowing for correction of the first depth and the second depth.    
   
   
       3 . A method for on-line registration and correction of downhole core depth information comprising the steps of: 
 a. providing a web portal for accessing digital images and well logging data and a server for storing the digital images and the well logging data;    b. allowing for uploading of at least one digital image of a core sample from a well to the server;    c. allowing for uploading of well logging data from the well to the server;    d. downloading and displaying the at least one digital image on a display device;    e. selecting a displayed interval from the displayed at least one digital image, the displayed interval being defined by a first depth and a second depth spaced from the first depth;    f. establishing an approximate actual depth value for the first depth of the displayed interval;    g. measuring the length of the displayed interval to determine an approximate actual depth value for the second depth of the displayed interval;    h. downloading and displaying the well logging data adjacent the displayed interval;    i. allowing for comparison of the well logging data and the displayed interval; and    j. allowing for correction of the first depth and the second depth.    
   
   
       4 . The method of  claim 1  or  2  wherein the providing of the at least one digital image of a core sample from a well is achieved by obtaining the at least one digital image from an oil company.  
   
   
       5 . The method of any one of  claims 1  to  3  wherein the display device is a computer monitor receiving signals from a user computer workstation.  
   
   
       6 . The method of any one of  claims 1  to  3  wherein the displayed interval is selected by means of: 
 positioning a mouse cursor over a first location on the displayed at least one digital image representing the first depth;    clicking a mouse button to select the first location;    positioning the mouse cursor over a second location on the displayed at least one digital image representing the second depth; and    clicking the mouse button to select the second location.    
   
   
       7 . The method of any one of  claims 1  to  3  wherein the first depth represents the top depth of the displayed interval, and the second depth represents the base depth of the displayed interval.  
   
   
       8 . The method of any one of  claims 1  to  3  wherein the first depth represents the base depth of the displayed interval, and the second depth represents the top depth of the displayed interval.  
   
   
       9 . The method of any one of  claims 1  to  3  wherein the approximate actual depth value for the first depth is established based on field data.  
   
   
       10 . The method of any one of  claims 1  to  3  wherein the length of the displayed interval is measured by means of a predetermined digital ruler that equates pixel numbers with a set length value.  
   
   
       11 . The method of  claim 2  or  3  wherein the providing of the well logging data is achieved by obtaining the well logging data from an oil company.  
   
   
       12 . The method of  claim 2  or  3  wherein the allowing for comparison of the well logging data and the displayed interval is achieved by means of displaying the well logging data and the displayed interval in parallel, adjacent orientation, enabling a user to visually inspect the well logging data and the displayed interval for correlation purposes.  
   
   
       13 . The method of  claim 2  or  3  wherein the allowing for correction of the first depth and the second depth is achieved by means of: 
 allowing a user to pick corresponding markers on the well logging data and the displayed interval, by means of mouse cursor positioning and location selection;    inserting correlation lines connecting the corresponding markers;    inspecting the digital interval to determine if there are any lost core intervals;    adding any desired sub-intervals to the displayed interval to represent lost core intervals; and    axially shifting the displayed interval such that the correlation lines are generally horizontal.    
   
   
       14 . A computer readable memory having recorded thereon statements and instructions for execution by a computer to carry out the method of any one of  claims 1  to  3 .  
   
   
       15 . A method for determining shale volume in a core sample from a well comprising the steps of: 
 a. selecting at least one region of a digital image of the core sample to represent a shale type;    b. specifying colour threshold values for the shale type;    c. specifying shale volume calculation options; and    d. calculating a shale volume value.    
   
   
       16 . The method of  claim 15  wherein a plurality of shale volume values are calculated, each at a discrete shale volume depth point, enabling plotting of a shale volume curve which can be displayed on a display device.  
   
   
       17 . The method of any one of  claims 1  to  3  comprising the further steps of: 
 a. selecting at least one region of the at least one digital image of the core sample to represent a shale type;    b. specifying colour threshold values for the shale type;    c. specifying shale volume calculation options; and    d. calculating a shale volume value.    
   
   
       18 . A method for enabling facies interpretation of a core sample from a well comprising the steps of: 
 a. displaying a digital image of the core sample on a display device;    b. defining at least one facies by means of characteristics including facies colour and minimum and maximum shale volume value cut-offs, the facies colour and minimum and maximum shale volume value cut-offs being determined by reference to the digital image of the core sample;    c. selecting a facies interval directly from the digital image by selecting first and second locations representing top and base depths of the facies interval;    d. identifying the at least one facies with at least a part of the facies interval based on the characteristics;    e. displaying the at least one facies on the display device according to the top and base depths; and    f. allowing for inspection and interpretation of the displayed at least one facies.    
   
   
       19 . The method of any one of claims  1 ,  2 ,  3  and  15  comprising the further steps of: 
 a. displaying the digital image of the core sample on the display device;    b. defining at least one facies by means of characteristics including facies colour and minimum and maximum shale volume value cut-offs, the facies colour and minimum and maximum shale volume value cut-offs being determined by reference to the digital image of the core sample;    c. selecting a fades interval directly from the digital image by selecting first and second locations representing top and base depths of the facies interval;    d. identifying the at least one facies with at least a part of the facies interval based on the characteristics;    e. displaying the at least one facies on the display device according to the top and base depths; and    f. allowing for inspection and interpretation of the displayed at least one facies.    
   
   
       20 . The method of  claim 2  or  3  comprising the further step of using corrected top and base depths to annotate the at least one digital image.  
   
   
       21 . A digital core workflow method comprising the steps of: 
 a. providing at least one digital image of a core sample from a well;    b. providing well logging data corresponding to the core sample;    c. displaying the at least one digital image on a display device;    d. selecting a displayed interval from the displayed at least one digital image, the displayed interval being defined by a first depth and a second depth spaced from the first depth;    e. establishing an approximate actual depth value for the first depth of the displayed interval;    f. measuring the length of the displayed interval to determine an approximate actual depth value for the second depth of the displayed interval;    g. displaying the well logging data adjacent to the displayed interval;    h. allowing for comparison of the well logging data and the displayed interval to enable selecting corresponding depth markers on the displayed interval and the displayed well logging data, and to enable adjusting lost core intervals;    i. allowing for correction of the first depth and the second depth;    j. selecting at least one region of the at least one digital image of the core sample to represent a shale type;    k. specifying colour threshold values for the shale type;    l. specifying shale volume calculation options;    m. calculating a shale volume value;    n. defining at least one facies by means of characteristics including facies colour and minimum and maximum shale volume value cut-offs, the facies colour and minimum and maximum shale volume value cut-offs being determined by reference to the at least one digital image;    o. selecting a facies interval directly from the at least one digital image by selecting first and second locations representing top and base depths of the facies interval;    p. identifying the at least one facies with at least a part of the facies interval based on the characteristics;    q. displaying the at least one facies on the display device according to the top and base depths;    r. allowing for inspection and interpretation of the displayed at least one facies; and    s. using corrected top and base depths to annotate the at least one digital image.