Geology Interpretation Project Big Injun Sand & Trenton-Black River plays, Central Appalachian Basin, WV

Transcription

1 Geology Interpretation Project Big Injun Sand & Trenton-Black River plays, Central Appalachian Basin, WV Part 1 - Access and Basic Interpretation of the Seismic Data Using Kingdom T. H. Wilson (2005) 1

2 2D Fault/Horizon Interpretation Using Seismic Micro-Technology s Kingdom Suite Seismic Micro-Technology's Kingdom software is accessed through the Windows Start Programs Menu. In your program list select Kingdom Suite and then left-click on Kingdom. NOTE: Left clicking the mouse is used to start, continue and end an activity. Right clicking is ONLY used for displaying various pop-up menus. Project files are opened from the initial Kingdom Suite window (Figure 1). Click on Project then Open Project in the drop-down menus. Figure 1: The initial Kingdom Suite display window provides access to new and old project files. This exercise uses the 554Expl data set, which is accessed through the network drive. In this exercise, we begin with a general introduction to the data and then continue with the fault interpretations. Generally one would pick the faults first to prevent the computer from carrying reflectors directly across faults during horizon interpretation. 2

3 Procedures: When you open a project under Kingdom, the basic windows layout will contain a 3D basemap (right) and project tree (left) (Figure 2). Figure 2: Basic window layout showing project tree and 3D grid basemap. 1. Left click on one of the lines to activate it. In this example, position the mouse arrow on Line 6. Right click and select Display 2D Line 6. The seismic line will now appear as shown below in Figure 3. *Color display options will be covered in class, so you might want to take some notes. 3

4 Figure 3: Display of line 6 with color bar. 2. If you prefer another colorbar, left click on View and Colors. Click on File and Open and select a different colorbar. In most cases, the name of the colorbar describes the colors and the number of colors in the colorbar. For example, the default colorbar, brwbl50.clm, is a blue-white-brown colorbar with 50 colors. Close the color editor once you are satisfied with a colorbar. Alternatively, you can click on the turquoise arrows left or right and go from color bar to color bar. 3. If you want to see wiggle traces, left click on View and Type of Plot and select Wiggle Variable Area. You may need to change the display scale to obtain the desired view. The variable area wiggle trace display will appear as shown below (Figure 4). Note the other display formats for future reference. 4

5 Figure 4: Variable area wiggle trace display format of Line To change the display scales, left click on View and Set Display Scales or click on the scale bar at the top of the seismic line display window. Try 8 traces per inch and 25 inches per second to provide a close-up (Figure 5) view of waveform character in the vicinity of the well shown above (Figure 4). Use the scroll bars to position yourself within the line. Figure 5: Close-up view obtained using 8 traces/ inch and 25 inches/second. 5

6 5. You can orient yourself to geographical directions by moving the cursor on the seismic window (Figures 4 or 5) and watching the cursor movement on the map. If the direction is backwards hit the R key on the keyboard to reverse the line direction. 6. The colorbar may or may not be displayed on the seismic window. To display colorbar, left click on View and Toolbars and then Color Bar. A check indicates on. 7. Display features can also be accessed directly using the buttons (Figure 6) in the upper left corner of the trace window. Figure 6: Shortcut buttons on the line display window. Buttons, left to right, select seismic line, wiggle overlay, vertical seismic display scale, color bar editor, a toggle switch to display the color bar, and two zoom control buttons. The drop down window at right allows the user to select from time or data type. 8. On the seismic line, there are two fairly prominent faults. We will be trying to keep track of at least two faults and now would be a good time to assign a name to them. To assign the faults, right click on the seismic window and select Fault Management. From there, select the Create tab (Figure 7) and enter a name and color for the easternmost fault. Left click on Apply. Enter a name and color for the major fault and then either OK or Apply. Create new faults if desired, You're now in the fault picking mode with the last created fault active. Figure 7: Fault surface management window. 6

7 9. Display the fault toolbar to allow for quicker selection of the faults you wish to pick. To do this left click on View and Toolbars and then Faults. All the displayed faults are present, including Unassigned. Hot keys or short-cut keys are available: D enters the user into the fault digitization mode, A assigns a fault, and "S" de-assigns. Faults Toolbar Faults digitizing window 10. To start picking your fault, make sure your line is oriented west (left) to east (right) left click on the Margin fault. To begin digitizing hit the D-key and then left click on the fault break that courses through the seismic data. A rubber band should appear as you go from point to point (Figure 8). Continue left clicking points along the fault until you either need to scroll vertically or horizontally to view fault extensions outside your current view (Figure 8). Use the scroll bar to move the display so that more of the fault is visible. Continue until you can no longer pick this fault. Double click to end. If you enter a point you don t like, you can back up or delete the last point by hitting the Esc key To follow the fault downward through the data, drag the rubber Figure 8: Individual band over points to the digitized scroll bar along and the slide fault down appear as you as black normally squares connected by a thin black line (or rubber band). 7

8 would. Your fault interpretation may look something like the following (Figure 9): Figure 9: East Margin fault digitized on Line Create another fault (unless you already did). Left click on the second fault displayed in the Faults digitizing menu to activate it and then hit the D" key to begin digitization. Begin picking the second fault. If you choose to pick some of the other faults on the Faults Toolbar, simply activate (click on) the appropriate named or unassigned fault, hit the D key and start picking. The two faults you just picked should appear as shown in the view below (Figure 10). The number of points used to digitize the fault will vary from interpreter to interpreter. 8

9 Figure 10: Faults just digitized on the northwestern end of Line 6 appear as shown above. Note that the green fault is still active. 12. If you want to edit some of your picks, the fault is active so long as the square dots are present. Note that the green fault in the above display (Figure 10) is currently active. When a fault is selected for further editing, little handles appear on each digitized point. To move individual points, activate the fault and then left click-and-hold on the digitized fault point. As you move the mouse, the digitized point will also move. If you move a small distance, you may have to use the Esc key to undo the rubber band. 13. If you would like to move the entire fault line, first activate the fault and then hold the Ctrl key and then left click and hold on any part of the fault line. Move the line to wherever you like and then release the mouse button and Ctrl key. 14. To delete a fault segment, make it active and then hit the delete key on your keyboard. 15. To add points, left click on an existing point, add the appropriate intervening points, and double click on another existing point. 9

10 16. To remove consecutive points, left click on an existing point, skip the 'bad' points and double click on an existing point. 17. If you'd like to change the active fault, left click on the new fault to activate it or select from the Faults Menu. If the new fault has no existing digital points, you must hit "D" on either the keyboard or Faults Menu. 18. To assign an unnamed fault, activate the fault name, activate the unassigned fault line and then hit the A-key. 19. To de-assign a named fault, activate the fault line and then hit the S-key. 20. Once the faults have been picked on this line, you can begin picking the faults on the remaining lines in the database. Since there is a sparse distribution of lines, you may want to keep track of fault extents on individual lines. This may help you determine what fault you are dealing with on the remaining lines. For example, to locate the Margin fault on the base map, just double click the Margin Fault in the Properties Window Fault list (Figure 11). Click on Margin Fault in your Faults list Figure 11:When you double click Margin Fault in your Parameter Window Faults list, a fault segment display will appear. 10

11 Figure 12: Closeup view of the fault segment on Line 6. Colors represent two-way travel times to the fault surface. Color bar is shown at right. Note that a color strip appears on the line (Figure 12). The colors portray travel time to the fault along its extent. Complete your digitization of the Margin and 2 nd fault, and double click individual faults in the Properties Window Fault listing. The Margin fault is shown below Figure 13: Fault segment view of the East Margin fault observed in our seismic data set. 11

12 21. Fault surfaces can be interpolated between lines, but the interpreter should exercise caution and not accept the validity of the interpolated fault surface without close scrutiny. In fact, in cases such as this one where large gaps separate individual seismic lines, the interpolations almost certainly introduce spurious fault plane features (Figure 14). Figure 14: Interpolated fault surface. To view the interpolated fault surface use map window control icons (Figure 15) in the upper left corner of the map window (Figure 14). From the drop down window select Fault Surface. Figure 15: Shortcut icons available on the map display window. Buttons, left to right, allow the user to Select fault surface to display, Select Contour Overlay, Set Contour Parameters, Set Scales, Edit Colorbar, Show Colorbar, magnification control buttons, and a selection window that allows you to switch back and forth from Fault Surface and Fault Segment displays. 12

13 The problems with contour interpolation across large gaps in the data can be minimized using options in the fault management window. Right click on the map view and select Fault management window. Click on the display folder in that window and examine the various options available to help control the fault surface display. Note the Surface Smoothing option (see Figure 16 below). Set that to high. And OK to exit. Figure 16: The display folder in the fault management window. 13

14 The smoothed map (Figure 17) provides a more reasonable view of the likely fault surface geometry. Figure 17: Smoothed fault surface time contours for the East Margin fault. Assignment: Complete your mapping of the East Margin fault and the 2 nd fault out. Be prepared to show progress on this 14