Multiple Data Types and Cross Plot

Cross plot can be used for the same data type between different wells. The shifted crossplot (C.plotShifted) from the Graph pull down menu aligns all marker before making the crossplot, and can be used to examine the correlation between the wells.

To use multiple data types, each data type should be assigned a name so that they can be correctly identified. Suppose there are two projects, TESTRES containing resistivity data and TESTPOR containing porosity data. To avoid changing the original data by mistake, Open TESTPOR and Save As TESTPOR2. Now from TESTPOR2, go to the FindFile panel from the File pull down menu, select the TESTRES.BD1 data file, then click Add > button and select Add to FanSection & Rename option. This will add the resistivity data into the TESTPOR2 project along the fan section linking the wells with porosity data and rename the porosity data to por (assuming the first porosity log is named por) and the resistivity data to 2nd. If the same wells contain both resistivity and porosity data, the same number of resistivity logs will be added. If more wells contain resistivity data than porosity data, less wells than what is in TESTRES.BD1 will be added.

To change the added data from named 2nd to resistivity, go to the Data&Units panel from Options pull down menu, type in resist in the Change Name To field, click Change Name pull down button, and select 2nd. In order to show both data traces on the same Data Trace graph, select the Primary Name to be por and Secondary Name to be resist. The minimum and maximum fields will be updated automatically. Without explicitly selecting the names, the minimum and maximum will remain 0 and only the primary data will be plotted. Now Close the Data&Units panel.

The Data Trace graph shows the first well or the first selected well.

The Crossplot shows the first well or the first selected well as one color (red) and the total data in another color (blue). To turn one of them off, go to Graphpar panel from the Options pull down menu, select 1(current well) or 2(total) to be the Active Object (mid lower left of panel), then modify the display options (mid lower right of panel) to select the Not Show option.

Since resistivity is log-normally distributed, select YLog option from Format pull down menu to use log scale for resistivity.

Select Linear Fit option from Tools pull down menu to fit a line and show the coefficient of correlation. The line fit is applied to the displayed data. The equation of fit can be used later to transform the data.

The depth range for sampling data into the cross plot is determined in three different cases:

1. When Fan section is graphed in one of the four pictures (including in the background) and the Section Zoom Depth Range option in the Analysis panel from Options pull down menu is checked, the depth range displayed in the Fan section graph is used for the current well.

2. When the above conditions are not satisfied, and when there are at least two horizon markers active, the depth range is taken between the top most and bottom most active markers. If Zone Margin in the Analysis panel from Options pull down menu is not zero, the margin will be added above and below the markers.

3. If neither of the above cases are applicable, the Top and Bottom range in the Analysis panel from Options pull down menu will be used. This range is initially set from the most common top and most common bottom of all the data.

This depth range selection scheme is also used for the variance graphs.