Friday, June 30, 2017

MS Thesis Ideas

Here are some ideas that have good scope and purpose for master's projects.
  1. Seismic P-wave velocity of near surface formations in NW Arkansas
  2. Seismic S-wave velocity of near surface formations in NW Arkansas
  3. Ground penetrating radar at Pedro site to image base of Miss carbonate mounds
  4. Seismic P-wave anisotropy of near surface fractured Chattanooga shale 
  5. Seismic S-wave anisotropy of near surface fractured Chattanooga shale 
  6. Seismic P-wave refraction survey and geological correlation at a well site in NW Arkansas
  7. Seismic properties of Boone regolith in various stages of weathering

Monday, October 10, 2016

Petra Projects

Some of our geology masters students do mapping projects using IHS Petra software. We try to capture these Petra project files so that future students can benefit from those who went before. Dr. Liner is the keeper of some Petra projects and Jamie Woolsey also maintains several.

Some Petra projects:

NE OK and NW AR (Kevin Liner, 2014)

Arkansas raster logs (Jamie Woolsey, 2015)

Western Arkoma Basin (Yueyang Wang, 2016)

Thursday, June 30, 2016

Geology TA Application Process for Spring 2017

The Spring 2017 semester applications admissions and teaching assistantships will be due October 15th. The coming fall semester assitantships and positions have already been filled.  

To complete the application go to:

From there the grad school will assign you a login name and password. (give that a few days).
After that upload all necessary materials including statement of purpose and CV. Be sure to mention you are interested in a teaching assistantship

Teaching assistantships ($11,000 for 9 months for MS level, $13,000 for 9 months PhD level) in the department typically involve teaching undergraduate intro geology, and occasionally upper division undergrad classes. Research assistantships are dependent on your thesis advisor. If they have money for an RA, basically. 

Additional information can be found at the department website: 

(info from Dr. Celina Suarez, Geology graduate student coordinator)

Monday, March 14, 2016

Basic Depth Conversion in OpendTect

Version: OpendTect 6.0.1

We routinely track a horizon in OpendTect to make time structure and horizon amplitude maps. But we would also like to make at least a basic contoured depth map. This is the simplest possible depth map since we are using a constant velocity for depth conversion. In areas of subtle structure it should be reasonably accurate. Here is the workflow:
  1. This example is in the Wild Creek 3D survey, the horizon is a Lower Penn (LPenn) horizon, just below Oswego (Fig. 1) and the well is the Modica_1A-17. Even though this well is projected from 1.5 miles away, we will use it for this example. (Seismic data credit: Osage Nation Minerals Council; Well data credit: Spyglass Energy).
    1. Numbers we need.... 
      1. Wild Creek Survey = +1200 ft = SRD... seismic reference datum
      2. Modica_1A-17  = +954 ft = KB ... kelley bushing
      3. Event time at Modica Well = 0.533 sec = T ... reflection time
      4. Event depth at Modica Well = 2575 ft = MD ... measured depth from KB
      5. Event depth at Modica Well = 953 - 2575 = -1622 ft TVDSS ... depth sub-sea
    2. calculate depth conversion velocity
      1. V = 2*(MD - KB + SRD)/T = 2*(2575 - 953 + 1200)/0.533 = 10589 ft/s.... this is our constant velocity for depth conversion. The velocity will scale horizon times to depth from SRD. This depth will need to be subtracted from SRD to get TVDSS.
  2. In the project tree add your 3D horizon and make the usual time maps
    1. Horizon time structure with contours (Fig. 2)
    2. Horizon amplitude with time structure contour overlay (Fig. 3)
  3. On the top toolbar choose the Edit Attributes icon 
    1. Choose the <All>/Horizon attribute for your horizon and data type and Z output. Name this attribute T_LPenn and Add As New (Fig. 4)
    2. Choose the <All>/Mathematics attribute for your horizon and implement the depth conversion equation TVDSS = SRD - V * T / 2 and for 'T' use T_LPenn.  Name this attribute TVDSS_LPenn and Add As New (Fig. 5)
  4. On the project tree under the LPenn horizon add the T_LPenn attribute, then right click on T_LPenn and select Save As Horizon Data... 
  5. On the project tree under the LPenn horizon add the TVDSS_LPenn attribute, then right click on TVDSS_LPenn and select Save As Horizon Data... 
  6. Add contours for T_LPenn (Fig. 6) and TVDSS_LPenn (Fig. 7)
    1. Zoom near Modica well of TVDSS_LPenn color and contour map shows sub-sea depth near well is within 5 ft of the correct -1622 ft value (Fig. 8)
Figure 1. LPenn event (red) and Modica well with formation tops

Figure 2.  LPenn time structure (color and 4 ms contours)

Figure 3. LPenn amplitude and time structure contours

Figure 4. Horizon attribute defining T_LPenn

Figure 5. Mathematics attribute defining TVDSS_LPenn

Figure 6. LPenn time structure (T_LPenn) with 2 msec contours
Figure 7. LPenn TVDSS with 10 ft contours

Figure 8. Zoom LPenn TVDSS with 5 ft contours

Tuesday, March 8, 2016

Isochron and Isopach Maps in OpendTect

Version: 6.0

The example given here is the interval between Upper Fayetteville SH and the Boone LS in the Desoto 3D seismic survey of NE Conway County, AR (data credit: SWN). Horizon tracking by Daniel Moser.

Isochron map: Seismic two-way interval time between two horizons
Isopach map: Thickness interval between two geological or seismic horizons

  1. In the project tree add two horizons A and B, here A=U_Fay_Smooth (Fig 1) and B=Boone_Smooth (Fig 2)The A horizon is shallower than B.
  2. Right click on shallower horizon U_Fay_Smooth and select Workflows > Calculate Isochron ...
    1. In the isopach parameter window set Calculate to menu to Boone_Smooth  use default attribute name I:Boone_Smooth, and output result in msec. 
    2. You will see there is a new attribute I:Boone_Smooth in the U_Fay_Smooth tree list. 
  3. Right click on the I:Boone_Smooth attribute and select Tools > Set Z Values ...
  4. In the parameter window select: Values are Relative (deltas), Units are msec, Save Horizon As new, output horizon name UFay_Boone_iso and check the Display after create box. This will generate a horizon representing the isochron between the horizons. Contours can be added to show the isochron between these two horizons (Fig 3).
U_Fay_smooth horizon time structure with 2 ms contours

Boone_smooth horizon time structure with 2 ms contours

Fay-Boone isochron with 2 ms contours

Not yet... generate isopach from isochron (CL)
  1. Choose menu item Scene>New[Depth]. In the parameter box select Linear Velocity and set the Vint parameter to 12000 ft/s (from averaging of sonic velocity between U Fay and Boone) and set gradient to zero. This forces a constant velocity depth conversion. Select OK.
  2. A new project tree window appears below the previous project tree along with the new scene window. Minimize the original scene window and maximize the new one.
  3. In the depth scene add the UFay_Boone_iso horizon 

Monday, March 7, 2016

Traditional Horizon Tracking in Faulted Terrain

Version: OpendTect 6.0

This entry explains how to use OpendTect to track horizons in faulted areas by working in vertical sections.

We will assume that the work area is small, there are only a few faults and these can be identified as individuals allowing named faults to be used from the outset.

Here is the workflow for a region of interest (ROI):
  1. Identify fault block and horizon of to be mapped
  2. Identify faults that bound your fault block
  3. Scan through ROI on inlines (IL) and cross lines (XL) and determine which gives best view of horizon and faults in ROI. We assume you will work on IL sections here.
  4. On the project tree create a pickset and place a pick on your horizon and its correlation across faults that bound your block. Note what IL the picks are on
  5. Create horizon and set appropriate tracking parameters
  6. Create all faults you will need, naming them logically (e.g., F1, F2, F3, etc)
  7. Go to the IL that gives the best view of your faults and horizon correlation across them
    1. Set IL jump to 20, 10 or 5 depending on size of area and complexity of structure
    2. Select horizon from project tree and place seeds at each end of each fault block as close to the fault location as possible
    3. Select F1 from project tree and place picks. Be as consistent as possible on picking shallowest and deepest fault point on each IL
    4. Same for F2, F3, etc.
    5. Jump to next IL location, make horizon and faults only visible at sections (hotkey v) and repeat steps 7-2 through 7-4
  8. Go to Z-North view
    1. Hide all faults
    2. Make horizon visible in full (hotkey v), you should see all the seeds you picked.
    3. From the tracking parameter window, select Retrack All. This forces tracking from all seed points simultaneously. 
    4. Assuming you have the entire data set preloaded, watch until your horizon tracking progresses beyond your ROI, then hit the red Stop Auto Tracking button on the tracking parameter window. 
  9. Review the time structure map for jumps that indicate tracking busts inside fault blocks. We expect time structure jumps at faults. 
  10. If there are tracking busts
    1. Repeat step 7 in the bust area with a smaller IL jump interval
    2. Repeat step 8
    3. Repeat step 9
  11. If there are no tracking busts
    1. Make faults visible (hotkey v)
    2. Select horizon on project tree and use polygon/rectangle tool to trim tracked area to ROI
  12. Make contours, show amplitude, etc for final display
Figure 1. Vertical seismic IL section with pickset points identifying horizon to be mapped

Figure 2. Same IL after defining horizon and faults, then picking them in this line

Figure 3. Map view of horizon seeds (green) and traced ILs (red)

Figure 4. Final after auto tracking, trimming to region of interest, adding time structure contours and 3D display with faults