Tag Archives: logs
Strange Log Appears Far Above Other Logs When Hanging Section on Selected Stratigraphic Horizon
If you’re hanging a section relative to a stratigraphic horizon within RockWorks16, and you see a strange log floating way above all of the other logs, here’s what’s going on …
The offending borehole does not contain any reference to the stratigraphic unit (in this example, the top of the Potosi Formation) that was selected as the datum. As a consequence, it remains at it’s correct structural elevation while all of the other logs have been vertically offset such that the datum contact is adjusted to an elevation of zero. In other words, the program is working just fine – but a fat lot of good that will get you.
Here’s the solution …
Step 1. Zoom in on the offending log …
Step 2. Make note of the log ID. In this case, that’s “DH-05”. This, of course, assumes that you have elected to plot the log titles within your cross section. If not, turn on the titles and try again.
Step 3. Uncheck the offending log within the Borehole Manager database.
4. Re-run the cross-section program …
5. Be happy.
New Version of RockWorks16 (2013.8.8) Available
Creating Batch PDF Output for Your LogPlot Logs
If you want to create PDF output of a bunch of logs created with LogPlot7, you can automate this using the Log | Batch Compile menu command. Here are the steps I’ve taken to set this up. NOTE that this requires that you have a PDF program, such as Adobe Acrobat Pro, or any of the free PDF printers (PDF995, CutePDF, etc. – see RockWare forum postings regarding these) installed as a printer in your Windows system.
1. First, be sure you’re using a build of LogPlot7 that is 18.104.22.168 or newer.
2. Set up your PDF printer as the default printer in LogPlot, using the program’s File | Setup command. (On some systems you may also need to set up the PDF printer as default in the Windows Control Panel before launching LogPlot.)
3. You can set up the page size for the printer as well.
4. Set up the PDF printer driver to NOT prompt for PDF file names, and set the output folder to the same folder where the data files reside. I’ve attached an example of what my Acrobat Professional screen looks like, though your version or your PDF printing software may be different. Note that this is an important step so that you won’t be prompted for each PDF output file name.
5. Then, select the Log | Batch Compile menu option in LogPlot.
6. Click the Add button, and in the Batch Editor window define the name of the data file, the log design, scale, and other compile settings. Be sure Print is selected, and be sure the Save as LPT file is also selected and a name defined. (The PDF file name will be based on the LPT name you define here.)
7. Click OK when you’re done, and you’ll see this log’s items listed in the batch window.
8. Repeat for additional files, though you might start with just a handful to get the hang of it and to be sure the PDF files are actually being created.
9. Save your batch at some point, using the Save button in the Batch Compile window. At a later date, you can use the Load button in this window to load an already-saved batch listing.
! Note: the BTC file that is created is an ASCII XML-type file. If it is easier for you to modify the BTC file directly to add other logs, you certainly may do so, just be careful about the XML syntax.
10. To run the batch, just click the Go button at the bottom of the Batch Compile window. LogPlot should load the selected DAT file, compile it into the selected LDFX file using the indicated settings, save the requested LPT file, and print to PDF, storing the PDF file in the requested folder. It will repeat this process for each item listed in the batch.
11. If you want to append all of the PDF’s into a single file, you can use Adobe Acrobat’s File | Combine | Merge Files menu option.
Computing Aggregate Reserves for a Site with Two Isolated Carbonate Units
This paper describes how to use RockWorks to compute total economic reserves for a site that includes two carbonate units: an upper limestone and a lower dolomite, separated by a shale unit. It involves creating separate I-Data models using the Stratabound filter, combining the models, and checking them against the observed log data.
Link to original paper: http://www.rockware.com/assets/products/165/casestudies/6/9/computing_aggregate_reserves.pdf
The purpose of this study is to compute the total economic reserves for a site that includes two carbonate units; an upper limestone and a lower dolomite separated by a shale unit. Quality analyses have been obtained at one-foot intervals within the carbonates. The following diagram depicts a typical log showing the lithology, stratigraphy, and aggregate quality.
Step 1. The Problem
Modeling the rock quality en-masse is problematic because the node values would include the quality values for both the limestone and the dolomite. The following diagrams depict a solid model based on the rock quality and a stratigraphic block model. Notice how the rock quality (I-Data) model interpolates quality values where there is no corresponding carbonate.
Compare this stratigraphic model with bulk rock quality model above and note how quality values were interpreted within overburden (light yellow) and interburden.
Step 2. The Solution
The solution to this problem is to use the “Stratabound” option within the I-Data / Model menu. Two rock-quality models were created; one for the upper limestone and another for the lower dolomite.
In the example below, the I-data model is confined to points and nodes within the Hanford Limestone unit.
In this example, the I-Data model is confined to points and nodes within Shuller Dolomite.
Step 3. Combining the Models
The next step involved adding the two models together and removing all voxels with a quality value less than 50 (the minimum acceptable quality).
Step 4. Checking the Model
The final, and most important step, is to create a 3D log diagram, combine it with the final ore model, and examine the data to see if it make sense.
Step 5. Conclusion
By combining the preceding approach with increasingly more tolerant filter cutoffs, it is possible to create a mining strategy that will yield the highest return on investment from the onset.
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