Interactive Petrophysics calculate shale volume

The Clay Volume interpretation module is used to interactively calculate clay volume curves from single clay indicator or multiple clay indicators

Single Clay Indicators use a single log curve to define clean and clay cut-offs

The Double Clay Indicators are defined in the middle section of the Clay Volume Analysis dialog. These are standard curve crossplot combinations (Density/Neutron, Density/Sonic, and Sonic/Neutron).

The Bad Hole Indicators for Double Clay Indicators section allows the selection of curves to be used in the Clay Volume Interactive Plot to discriminate where the Double Clay Indicators will be used. For example, a caliper curve could be used as the Bad Hole Indicator to determine where a Density/Neutron Double Clay Indicator is not going to be reliable.

For example when using the caliper log as a Bad Hole Indicator, setting the minimum threshold parameter BadH1Min, the Bad Hole Indicator will switch off the Density/Neutron Double Clay Indicator where the caliper is greater than the specified threshold value.

Define the Bad Hole Indicators by selecting the check boxes on the left hand side of the dialog.

The Minimum Clay Volume (VCL) curve is calculated as the minimum clay volume response of all selected single and double clay indicators, Click the Run button to start the Clay Volume analysis.

IP will display a message dialog asking if the log plot should be re-initialized. Click Yes to confirm the re-initialization of the log plot and the activation of the Interactive Log Plot Features. Click No to keep the current Log Plot active.

If this is a new Run, then default parameters will be calculated for each clay indicator and these values will populate the Clay Volume Parameters Set. These defaults are not meant to be the optimum interpretation parameters, but are chosen simply to set the parameters within the correct range of values for a particular single curve or pair of curves.

For the Single Clay Indicators the defaults are generally the maximum and minimum readings for the indicator.

For the Double Clay Indicators the defaults will be the sandstone line for the clean line, and the shale point will be chosen towards the bottom right hand edge of the shale points, as seen on a standard crossplot.

The Clay Volume Interactive Plot consists of (from left to right): A Depth track, Zone track, Single Clay indicators (one per track), Double Clay indicators (one per track), a Bad Hole track and a Result track containing a curve for each of the clay indicator interpretations.

By right clicking in a track , a pop-up menu will appear. Firstly, this allows you to turn On / Off the indicator in this zone. Secondly, you can select a histogram plot for the indicator. This will allow you to change the parameter values using the interactive lines on the histogram plot

The bad hole indicator track will only be displayed when a curve is selected as a bad hole indicator in the Clay Volume Analysis module. Initially, the bad hole indicator logic is not active nor are its cut-off parameters set. The cut-off values need to be initialized in the Clay Volume Parameters interface and then they will be displayed as vertical lines in a log track on the Clay Volume Interactive Plot. Once displayed, the cut-off values can be changed interactively as described in the single indicator section above.

The Double Clay Indicators work on the principle of defining a clean line and a clay point. The clay volume is calculated as the distance the input data falls between the clay point and the clean line. The following plot illustrates the principle:

for additional resources please visit my Blog http://geo4all.info/