Method and apparatus for creating horizons from 3
Contents
1. 012 2 18 82 18 zs FIG 11 U S Patent Oct 29 1996 Sheet 4 of 4 5 570 106 12 Al MOUSE DIRECTION N DELETE AND SCAN A TOE DELETE AND SCAN A TOB 5 570 106 1 METHOD AND APPARATUS FOR CREATING HORIZONS FROM 3 D SEISMIC DATA BACKGROUND OF THE INVENTION 1 Field of Invention This invention relates generally to the field of seismic data interpretation In particular the invention relates to a machine process for selection of three dimensional 3D seismic data or a horizon to provide petroleum exploration professionals more detailed understanding of subsurface geology and geometry Still more particularly this invention relates to an interactive method and apparatus by which an explorationist may change portions of a workstation monitor displayed horizon which has been created from a 3 D seismic data base 2 Description of the Prior Art FIGS 1 through 7 of the drawings illustrate features and methods associated with the prior art picking methods and are used herein to illustrate and define a horizon which has been picked from 3D seismic data and displayed on a workstation screen FIGS 8 through 12 illustrate apparatus and methods of the invention and are referenced in connec tion with the Description Of The Invention section of this specification below Only figures associated with prior art methods are introduced here FIG 1 illustrates a porti2. Data so as to display the horizon on the CRT Areas of dead or bad data appear on the horizon display where picking failed In a delete and scan mode between horizontally or verti cally adjacent areas the mouse is first clicked on a first area of good horizon points and then dragged i e with the mouse button on to and across a second area which includes bad or non existent horizon data The method of the invention as incorporated in the delete and scan computer program deletes all the data points in the second or dragged area rescans all the first clicked area and desig nates picked points of such area as seed points Such seed points are used to expand the scan into the dragged area The picked points of the second or dragged area are then used to fill in that space on the CRT display 5 570 106 5 For dragged areas that are neither horizontal nor vertically disposed with respect to the first clicked area on the CRT display a stair step application of the basic delete and scan method is used The program may be instructed by clicking the mouse on screen command buttons to delete the points of the dragged area to rescan the points of the dragged area to fill in the dragged area with picked points of a certain depth or to smooth the picked points across a horizon boundary BRIEF DESCRIPTION OF THE DRAWINGS The objects advantages and features of the invention will become more apparent by refere
3. moves a cursor 20 to different positions on the screen of monitor 14 Cursor 20 may be made larger and smaller on the screen by means of computer program and user interface mechanisms well known to computer programmers of ordinary skill in the art of interactive computer controls A hypothetical horizon 22 is shown presented on the screen of monitor 14 Such horizon is picked from a user supplied seed point or points using a picking or scanning computer program which manipulates 3D seismic data stored in a data base of memory The two large cross hatched areas 22 22 represent picked points of a strata in the earth which have two different depths On an actual workstation monitor such two different areas would be presented in two different colors to represent such different depths The areas of small cross hatching 24 represent holes or areas on the horizon which were not picked in the automatic picking method used to produce such display The picking methods used to produce such a horizon are described in U S Pat No 5 056 066 issued Oct 8 1991 U S Pat No 5 153 858 issued Oct 6 1992 and 6 U S application Ser No 08 046 026 filed Apr 12 1993 now U S Pat No 5 432 751 Such patents and application are incorporated by reference herein for their disclosure as 10 15 20 25 30 35 40 50 55 60 65 to automatic scanning or picking In order to manipulate the displayed horizon t
4. DENTIFICATION OF OBJECTS OF INVENTION A primary object of the invention is to provide a method and apparatus by which a user may interactively manipulate a horizon display on a CRT screen Another object of the invention is to provide a method and apparatus by which a CRT displayed horizon may be inter actively manipulated with a pointing device such as a mouse in order to delete areas of the displayed horizon which were not originally picked with the option of auto matically rescanning the deleted areas or filling in the horizon with interpolated data and smoothing the display across boundaries SUMMARY The objects of the invention as identified above as well as other advantages and features of the invention are realized in an apparatus and method including a computer program used in conjunction with a horizon picking computer appa ratus Such apparatus and method scan 3 D seismic data to produce a horizon starting from one or more user input seed points The horizon is displayed on a CRT of the computer workstation The display may be accessed interactively by the user by using a computer pointing device commonly called a mouse Such mouse under user control controls the position of a cursor on the screen A computer program according to the invention is pro vided with computer apparatus which works in conjunction with the Horizon Picking Computer Program which has been employed to automatically pick or track 3D Seismic
5. United States Patent Viswanathan YR AE AR US005570106A Patent Number 5 570 106 Oct 29 1996 54 METHOD AND APPARATUS FOR CREATING HORIZONS FROM 3 D SEISMIC DATA 75 Inventor Venkatraman Viswanathan Katy Tex 73 Assignee Landmark Graphics Corporation Houston Tex 21 Appl No 98 506 22 Filed Jul 28 1993 SN ties ce ech aah ae GO1V 1 00 52 U S 345 133 367 72 364 421 58 Field of Search 367 72 73 38 364 421 420 345 115 118 121 162 156 157 119 145 133 56 References Cited 1 5 PATENT DOCUMENTS 5 056 066 10 1991 367 72 5 153 858 10 1992 Hildebrand et al 367 72 5 251 184 10 1993 Hildebrand et al 5 343 440 367 72 naa 367 72 45 Date of Patent OTHER PUBLICATIONS User manual Aldus Photostyler ver 1 1 Jun 1992 Primary Examiner Richard Assistant Examiner Kara Famandez Stoll Attorney Agent or Firm Bush Moseley Riddle amp Jack son L L P 57 ABSTRACT A method and apparatus for deleting and rescanning areas of a horizon display on a computer monitor is disclosed A cursor controlled by a pointing device such as a mouse is directed to a first area on the monitor which is adjacent a second area of the horizon which is described to be deleted and rescanne
6. ata of a displayed horizon and area B is in an area of unpicked data FIG 9 illustrates how the delete and scan program 52 interfaces with the Horizon Picking Computer program of 0 5 Pat No 5 056 066 or U S Pat No 5 153 858 Such program 100 operates on 3D Seismic Data using seed points to scan or pick the data of the 3D seismic data to produce the horizon display The scan and display program 52 of FIG 11 receives its input of points A1 B1 C1 D1 that is area A as described above by the click action of button 18 of mouse 18 5 570 106 7 Likewise the input of points A2 82 C2 D2 is achieved by dragging the cursor 20 across an area of unpicked points so as to define an area B Such input is indicated by logic box 70 Next control in the program 52 is passed to logic box 72 where all points picked points and unpicked points within the area defined by B1 82 C2 are deleted Control then passes to logic box 74 The points within area A are rescanned in the Horizon Picking program 100 and are designated as seed points Such seed points are used under control of logic box 76 in picking program 100 to pick points in the combined areas A and B Next such picked points are used to fill in the space of A1 B2 C2 D1 that is A and B and any space between A and B with the new picked data via display program 104 a program which interfaces between the computer 12 and monitor 14 FIG 12 illustrates the delete and
7. d data e g area 22 which is adjacent an area of non picked data e g area 24 The user manipulates the size of the cursor to correspond to the approximate size of the unpicked area In other words in the example illustrated in FIG 10 the vertical height of the cursor is made approxi mately equal through use of a zoom feature illustrated schematically by Zoom box and arrows 25 to the vertical height of the rectangular box of unpicked data immedi ately to the right of the cursor The user clicks a mouse button 18 to define an A area as shown on FIGS 10 and 11 Such click on the A area defines points 1 B1 1 and D1 of such area Next the user while holding down button 18 of mouse 18 drags the cursor 20 to and across the area 24 of unpicked data Such dragging of the cursor 20 specifies an area B defined by points A2 B2 C2 and D2 Points B1 and 2 and C1 D2 may be coexistent they may be distinct That is area A may be contiguous with area B or the two areas may be separated by a small distance between such areas FIG 11 illustrates a flow chart of the computer program 52 used to accomplish the delete and scan function from an area A to an area B Although area B is illustrated as being horizontally to the right of area A the method of the invention is the same where area A is to the right of area B or area A is beneath area B or above area B In each case area A is in an area of picked d
8. d The cursor is dragged from the first area across the second area while a user pushes the control button of the mouse thereby defining coordinates of an area for which all points are to be deleted The points in the first area are scanned to designate them as seed points Such seed points are used to pick horizon points in the second area Such picked points are then used to fill in the second area 5 Claims 4 Drawing Sheets DELETE amp SCAN DELETE RESCAN FILL SMOOTH ZOOM U S Patent FIG 2 PRIOR ART 2 TARGET TARGET SEED POINT TARGET TARGET ac FIG 4 SEED TARGET TRACE TRACE FIG 6 2 OR TIME Z OR TIME At 3 gt 72 Oct 29 1996 5 570 106 Sheet 1 of 4 FIG 1 PRIOR ART CROSSLINE FIG 3 PRIOR ART XYZ lt _ SEED C n POINT PICK 1 2 55 TARGET 4 a FIG 5 PRIOR ART a 1 PICK 795 7 TRACE oa 2 VERIFY PICK FIG 7 SEED TARGET TRACE TRACE U S Patent Oct 29 1996 Sheet 2 of 4 5 570 106 14 USER INPUTS PICKING METHOD SCORE HORIZON PICKING COMPUTER PROGRAM SCANNING HORIZON MANIPULATE COMPUTER PROGRAMS TO MONITOR U S Patent Oct 29 1996 Sheet 3 of 4 5 570 106 DELETE amp SCAN DELETE RESCAN FILL SMOOTH zoom N DELETE AND SCAN Re ATOB
9. d point is selected on a trace the trace is scanned up and down the z or time axis to find 5 570 106 3 the local extrema amplitude or simply extrema local extremum of a variable x where i is a digitizing index is defined as X lt XX EX Such scanning is bounded by zero crossings of the ampli tude of the trace in the case of a peak or a trough Such extrema will typically vary with time a small amount For example if To represents the seed point would typically represent the time of the extrema Next the time 15 started on the target trace On it the time is varied up and down between zero crossings of its trace amplitude until the nearest extrema is found Finally the time is used on the trace on which the seed point exists and on such seed trace scanning up and down the z axis is again performed for the nearest extrema If T equals T then iterative tracking has been achieved and tracking continues FIG 6 illustrates an example as to how an adjacent wavelet may not be picked in the iterative mode Notice that the time T is beyond the zero crossing window of the seed point Thus the target trace is not picked The amplitude acceptance test tolerance of the prior art iterative tracking mode defines a function A A2 b _ 2 A Amplitude of the target wavelet of the target trace at and A Amplitude of the seed wavelet from the s
10. e of y versus time traces is called a cross line Of course the y versus time traces may be designated a line and the x versus time traces called cross line In the seismic art vocabulary a horizontal section or time slice is a horizontal slice or plane through the 3D volume of data A plot of common attributes such as amplitudes of seismic reflection wavelets on x y axes as a function of their depth or time is similar to a surface topographic map but of course such a plot is of a subsurface strata Such a plot is called a horizon In other words a horizon is a surface along a bedding plane of a subsurface formation 10 20 25 30 35 40 45 50 55 60 65 2 In less than ten years computer aided exploration revo lutionized seismic exploration and field development Until recently however one aspect of seismic interpretation picking subsurface horizons or simply picking remained essentially unchanged from paper and pencil methods Traditionally picking was done manually by drawing with colored pencils on paper one seismic section or line at a time an incredibly tedious process In the early 1980 s interactive CAEX an acronym for Computer Aided Explo ration workstations gave seismic explorationists the ability to pick 3D data more quickly and effectively While inter preting seismic lines that is a two dimensional vertical slice or a vertical seismic section
11. eed trace at The value of S is bounded by values of 0 and 1 The more similar the two amplitudes the closer the 5 function is to zero The more dissimilar the two amplitudes the closer the S function is to 1 Next a score function is evaluated SCORE Sx9 0 1 The score is compared with a control value from 1 to 10 selected by the interpreter or user of the data Scores greater than the control value prevent a target trace from being picked FIG 7 illustrates a further horizon picking failure mode in addition to the method failure mode discussed above with respect to FIGS 4 and 6 and further in addition to the score failure mode discussed above The At failure mode specifies that an attempted pick is a failure if the difference in time from the time of the picked wavelet to the time of the seed wavelet is greater than a predetermined input At Times of wavelets are usually measured at their maximum amplitude FIG 7 illustrates that in the iterative mode a target wavelet may Satisfy the method picking test 1 iterative tracking is proper and the score test depending on the user s input of reference score but if the AT measured between the time of the target wavelet and the seed wavelet is greater than an input reference AT the pick fails After the tracking proceeds with each selected target trace becoming a seed trace for selecting more target traces a horizon has been picked The x y and t or z coordina
12. his inven tion provides a user by manipulating the mouse 18 and controlling the cursor 20 on the monitor with the capability to change the horizon display If a user observes areas on the displayed horizon which were not picked he may want to delete that portion of the displayed horizon and rescan that area or he may simply want to delete a section of the horizon and later rescan that portion or he may want to fill in an unpacked area with the data corresponding to a certain horizon depth or he may want to smooth the depth display between depth boundaries on the display FIGS 9 10 and 11 illustrate the basic method of the invention relating to the delete and scan procedure FIG 10 illustrates monitor 14 with function boxes 23 displayed on the screen according to the manipulative function available to a user Each function is achieved by pointing the cursor 20 to one of the boxes 23 through manipulation of mouse 18 With the cursor pointed to the delete and scan box of boxes 23 and a click of button 18 a signal is sent to the Horizon Manipulate Computer program 50 of FIG 9 that the delete and scan function that is computer program 52 is to be accessed upon the receipt of further data The user may want to change the user inputs for picking relating to the method picking score and AT Relaxed values from those originally used in picking the horizon may be desired Next the user manipulates the cursor 20 to a position in picke
13. least a portion of an area of said horizon display with picked points control button means on said pointing device means for defining a first set of coordinates for said first area and for defining a second set of coordinates for said second area said first area being contiguous with said second area to form a combined area computer program means for deleting all horizon points within said second area defined by said second set of coordinates computer program means for scanning all points in said first area and designating all points picked in said first area as seed points computer program means for using said seed points to pick horizon points in said combined area and computer program means for filling in said combined area of said horizon display with said picked horizon points from said combined area
14. ly the maximum amplitude of the reflection wavelet at that location in the volume of the data Other characteristics or attributes such as minimum amplitude phase frequency etc of the reflection at the x y z point may be used As illustrated in FIG first mode is for non iterative tracking which searches the seismic traces adjacent seed points for similar amplitude values picks the best one and then proceeds to the next available trace without double checking the accuracy of the pick FIG 4 illustrates an example as to how an adjacent wavelet may not be picked in the non iterative mode If a negative amplitude is sensed on an adjacent trace at the same time or depth then such target trace is not selected that is it is dead or an iterative picking mode verifies an adjacent trace as a pick by cross referencing the previous trace Once verified the adjacent trace is treated as a seed point and the picking of adjacent traces from it proceeds FIG 5 illustrates such prior art iterative picking Verification means that if the amplitude of the picked trace is within the limits of tolerance set by the user the pick is accepted Users can specify on a scale of 1 10 the degree of amplitude similarity they are willing to allow If a pick does not pass this acceptance test it is designated dead until at least one directly adjacent trace matches sufficiently to accept it specifically once a see
15. nce to the drawings which are appended hereto and wherein like numerals indicate like elements and wherein an illustrative embodiment of the invention is shown of which FIGS 1 7 were described in the BACKGROUND section above FIG 8 is an illustration of a computer workstation with a horizon displayed on its monitor screen CRT screen and with a pointing device such as a mouse which controls a cursor superimposed on the screen FIG 9 is a schematic diagram illustrating the interaction of a horizon manipulation computer program with other programs for picking horizons from 3D Seismic Data and displaying such horizons on the CRT screen FIG 10 is an illustration of a horizon displayed on a CRT screen with a mouse controlled cursor which is first clicked in an area of good picks and then dragged across an area which includes bad horizon data FIG 11 is a flow diagram which illustrates how a delete and scan function is performed by means of a computer program and FIG 12 is an illustration of a horizon having bad data which is manipulated by a mouse controlled cursor in a diagonal direction with a computer flow diagram of FIG 13 illustrating how the data is processed for diagonal manipu lation DESCRIPTION OF THE INVENTION FIG 8 schematically illustrates a workstation 10 includ ing a CPU 12 a CRT or monitor 14 and input devices including a keyboard 16 and screen pointing device or mouse 18 Mouse 18 through user interaction
16. on of a hypothetical 3D seismic data volume in order to explain the three dimensional rela tionships discussed in the text and accompanying drawings in this specification FIG 2 is an isometric view of a portion of five seismic traces which illustrates the relationship between a seed point and its four adjacent target traces FIG 3 illustrates a prior art simple or non iterative automatic tracking method FIG 4 illustrates an example of how a simple picking mode or method may fail to pick a target trace FIG 5 illustrates a prior art iterative autotracking method FIG 6 illustrates an example of how an iterative picking mode or method may fail to pick a target trace FIG 7 is a schematic illustration of a failure mode for picking in either the iterative mode or simple non iterative mode where the target wavelet is more than a predetermined difference in time for the seed wavelet FIG 1 is an isometric view of a portion of a hypothetical three dimensional 3D seismic data volume The small circles at the top of the volume represent the surface location of individual traces The vertical lines represent seismic traces which are measured in time or distance along the z axis of the volume Each individual trace is an amplitude versus time representation of an acoustic reflection from strata in the earth A sequence of x versus time traces is called a line by seismic explorationists A sequenc
17. ordinates for said first area by activating a control button on said pointing device defining a second set of coordinates for said second area by dragging said cursor of said pointing device from said first area to and across said second area said first area being contiguous with said second area to form a combined area deleting all horizon points within said second area defined by said second set of coordinates scanning all points in said first area and designating all points picked in said first area as seed points using said seed points to pick horizon points in said combined area and filling in said combined area of said horizon display with said picked horizon points from said combined area 2 The method of claim 1 wherein said first area and said second area are horizontally adjacent each other 3 The method of claim 1 wherein said first area and said second area are vertically adjacent each other 4 The method of claim 1 wherein said first area and said second area are diagonally adjacent each other 5 Apparatus for deleting and rescanning areas of a horizon display on a computer monitor where a horizon is a topographic representation of a subterranean strata derived from picked points of a 3 D seismic data base comprising pointing device means for directing a cursor to a first area of said horizon display adjacent a second area of said horizon display which is to be deleted said first area covering at
18. rescan of boxes 24 and after dragging the cursor across an area which has been deleted program 76 of flow chart 52 rescans the deleted data The fill function and smooth function of boxes 24 respectively fill in a space of deleted data with the same depth data as its surrounding area or interpolate depth data across a boundary of areas of two different depths Various modifications and alterations in the described methods and apparatus will be apparent to those skilled in the art of the foregoing description which does not depart from the spirit of the invention For this reason these changes are desired to be included in the appended claims The appended claims recite the only limitation to the present invention The descriptive manner which is employed for setting forth the embodiments should be interpreted as illustrative but not limitative What is claimed is 1 A method of deleting and rescanning areas of a horizon display on a computer monitor where a horizon is a topo graphic representation of a subterranean strata derived from wn 10 20 25 30 40 50 55 8 picked points of 3 D seismic data base the method comprising the steps of directing a cursor of a pointing device to a first area of said horizon display adjacent a second area of said horizon display which is to be deleted said first area covering at least a portion of an area of said horizon display with picked points defining a first set of co
19. scan procedure accord ing to the invention where a diagonal area of unpicked points 24 is to be deleted and rescanned In this case the cursor is brought to area A in the picked data portion of the horizon display The cursor is then dragged while continuing to hold the button 18 down so as to end for example at area E of the graphical portion of FIG 12 For such a diagonal case the stair step horizontal vertical regions B C and D are automatically defined to correspond with the diagonal move ment path of the cursor The delete and scan program 52 labeled Delete and Scan A to E as shown in FIG 13 then performs the delete and scan function of program 52 under control of logic box 82 In other words the program iden tified by reference number 52 of FIG 11 is performed from the area A to area B Next the delete and scan function is performed from area B to area C under control of logic box 84 Notice that such movement proceeds vertically from B to C Next the delete and scan function is performed from area C to D control of logic box 86 and then from area D to E under control of logic box 88 The other functions identified in FIG 10 are related to the invention described For example the delete function is achieved by clicking on the delete box of boxes 24 and dragging the cursor 20 across an area to be deleted The program 72 simply deletes all picked points in such display Subsequently the user may click on the box labeled
20. tes of each selected wavelet are stored in the computer memory A horizon is typically displayed on a CRT screen of a work station a powerful computer adapted for specialized uses such as seismic data interpretation CAD CAM work etc The display is usually an x y display of the seed point or points and all the picked points which correspond to the _ 5 20 45 50 55 60 65 4 seed point of the 3D seismic data The variation in depth that is time from the seed point is indicated for example by the color of the picked point As discussed above there are several ways that certain x y areas of the horizon may not yield picked data In other words there are areas of a typical horizon where blank or black areas are presented on the monitor display because of a picking failure Such failure might be due to a method failure as illustrated in FIGS 4 or 5 6 a score failure as discussed above or a AT failure as illustrated in FIG 7 An explorationist when confronted with a horizon presented on a screen observes areas which represent unpicked data The prior art of horizon picking apparatus and method has provided no means by which a user of a computer which includes automatic picking software and which displays a picked horizon on a CRT of the computer may interactively manipulate the horizon displayed on the CRT screen espe cially at areas where no horizon picks were made by the automatic picking program I
21. was still accomplished by viewing and picking one line at a time it could then be done by using a computer pointing device or mouse in combination with a display screen or monitor and clicking the cursor on a few selected points along a horizon and letting the machine pick all the rest of the points on that line This was the first type of automated picking and represented an incremental increase in both productivity and accuracy over manual picking A horizon is typically displayed on a CRT screen of a workstation that is a computer The display is usually an x y display including a seed point or points and the picked points through the 3D seismic data The difference in depth or time of the target points from the seed point is indicated for example by the color of the picked point In one prior art automatic system for tracking a bedding plane or horizon in a generally horizontal zone of 3D data a user selected or input at least one seed point which then expanded in all four directions within the 3D data volume as illustrated in FIG 2 until it reached the bound aries of a user specified zone Users had the option of tracking seismic data in one of two modes simple non iterative or iterative A seed point is specified by its x and y location and its time or depth i e the z axis of FIG 1 It is also specified by a characteristic of the reflection wavelet at that point Such characteristic is usual
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