Sunday, September 11, 2016

Xplotter - chart updates and some clay typing

This post is a continuation of the other week's mention of Xplotter - Cross Plots and Color Palettes.  While consulting and building a petrophysics business I am making my own tools instead of spending 60k+ on existing solutions.  Adding the ability to load charts onto plots went a lot quicker than I anticipated.  Last time we left off I was simply drawing the charts on the plot using MS Paint.  Now I've added a feature to save chart data in XML and load directly into Xplotter.

Below is an example of the RHOMA vs. UMAA chart.  When you correct density for clay, organics and porosity the values will fall within the ternary diagram so that you can determine the volume of calcite, dolomite and quartz.  In this example below I have just corrected for organics so it is along the way to mineralogy determination and still needs correction for clay and porosity.

Hand Drawn Ternary Diagram - last week

Program Generated Ternary - this week

I am now going through the different chart books and digitizing some of the more popular charts.  I'm going to avoid things like tornado charts and their million lines as much as possible.  I can only torture myself so much.

Below is an example of Gamma Ray - Potassium vs. Photoelectric Factor.  This chart is used for clay typing.  The example is from the Wolfcamp in south Midland Basin.  The expected clay type is illite and very little smectite / montmorillonite.  It is nice when the charts work out; makes my job easier.  All I did outside of Xplotter was add the colorful text boxes.  The colored outline boxes to highlight clay types were all drawn from XML templates.  

Gamma Ray - Potassium vs. Photoelectric Factor

Sure, I may have calibrated the boxes on the Gamma Ray axis, but that is because GR can be a highly qualitative measurement.  

There is another example you can use to do clay typing using spectral gamma ray; potassium vs. thorium.  To be honest, I've not used it very much because I've typically had XRD data to rely on.  But I am definitely going to use it for a basis of comparison for different resource shale plays.  I wonder how it will look when I compare SCOOP Woodford vs. Permian Wolfcamp vs. Ft. Worth Barnett.

Potassium vs. Thorium

XML template snapshot

And no example is complete without cross plotting neutron and density.  Here I have the lines from two charts on the same plot.  This allows me to compare the differences between charts and even service companies.  Below it is interesting to see how much a slight change in flushed zone water can have an effect on the density and neutron measurements for estimating porosity.  The slightly darker colors are from the more saline mud fluids.  

Neutron vs. Bulk Density

Thanks for reading!



  1. Thank you for this great article! I am like you used to use different diagrams. And most often I download diagram templates. One of the last diagram I downloaded is the process diagram template

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