The window directly to the left of the main form is the QuickView plot. After a LAS file is loaded, the first curve in the list which should be the Depth curve, will be displayed here. Clicking on a curve name in the data-list list will cause that curve to be displayed in the QuickView plot.
If the "Alt" key is depressed while clicking on a curve name, the curve data will be displayed instead.
The curves are displayed on the QuickView plot with a fixed format. The depth is scaled so that the whole data set fits on the page. Log curves are displayed with a pre-defined format. Log curves can wrap once, when they exceed the plot scale. A curve will change color to pink, when it is wrapped.
For log curves that don't have a format that is pre-defined, these are displayed with a linear scale and scaled so that the minimum and maximum values fit into the window. They are also plotted with a gray curve color.
Right clicking on the QuickView plot gives an option for copying the current image, so it can then be pasted into another document.
The figure above shows two features available after loading the data. On the left is a data view that is obtained by holding the "Alt" key down when clicking on a log channel name. The drop-down menu that appears when right-clicking on either the Company, Well and Dataset name is shown on the right.
4.2 Curve Sorting in the Datalist
Clicking on an item in the Datalist, will display a plot of the curve in the Quickview window, and list some information about the curve is displayed beneath the Datalist
Using an Up arrow or Down arrow key, after selecting an item in the Datalist, will shift the focus up or down.
Using a Page-Up or Page-Down key, after selecting an item in the Datalist, will cause that item to move up or down in the Datalist
Using a Shift->Page-Up or Shift->Page-Down key, after selecting an item in the Datalist, will result in that item to move to either the top or bottom of the Datalist.
Similar actions apply to the Company, Well and Dataset branches of the Datalist.
The curve data can be sorted alphabetically by either curve name or unit name, by right-clicking on the Dataset name and selecting a sort option.
4.3 Renaming and Deleting Data
Right clicking on the data-list gives a list of options that include renaming and deleting data.
Clicking on either the Well name, Company name or Dataset name allows to rename or delete the item that is selected. If a Well is deleted, then all the data under that Well will alos be deleted. Likewise, when a Company is selected, then all the Wells and data under that Company will be deleted.
Renaming the Company and Well in the datalist, only renames the data folder name. If the actual Well and Company names do need to be renamed, then this can be done in the Wellsite Data editor. Right click on the well folder in the data-lst to find the Wellsite Data editor
Individual curves in a LAS can be deleted the same way. To delete multiple curves, select the first curve as normal, then hold down the control key to select subsequet curvess. Finally, right click on the highlighted curve and select "delete".
4.4 Log Data Units
The depth units are specified inside the data file that was loaded, and the file will be loaded referenced to those depths units. The depth unit can be changed after loading by right clicking on the data-set, and selecting the "change depth unit" option.
Log Curve Units.
It is a simple matter to convert the units of a log curve by right clicking on the curve name, select the "Change Unit" option, then choose the desired unit.
The unit of the depth channel, which will be the first curve in the list, cannot be changed with this method. The depth unit is changed by changing the depth unit of the entire data-set as described previously.
4.5 Editing Log Curve data
Basic log curve editing can be done by right-clicking on a curve name in the data list, then selecting "Edit Curve".
A new window with the selected log curve in it will pop up. Currently, editing is limited to patching over data with a straight line, and nulling data.
Editing proceeds as follows
- Hold the T key down and click on the plot, will straight line the data to the top of the plot (T=top)
- Hold the B key down and click on the plot, will straight line the data to the bottom of the plot (B=top)
- Hold the G key down and click on two sequential points on the plot, and the intervening data will be straight lined (G is midway between the T and B keys on the keyboard)
- Hold the Y key down and click on the plot, will nullify the data to the top of the plot (Y is next to the T key)
- Hold the N key down and click on the plot, will nullify the data to the bottom of the plot (N is next to the B key)
- Hold the H key down and click on two sequential points on the plot, and the intervening data will be nullified (H is next to the G key)
Other key strokes available are:
- Control-Z undoes the last edit action. Multiple clicking Control-Z undoes multiple edits from the current edit session.
- Control-X expands the depth scale
- Control-S decreases the depth scale.
Null values in the log data can be easily identified by the black bar on the left side of the "Edit Curve" window, as shown above.
4.6 Null Value handling
Null values represent sections of the log data where a measurement was not obtained or is missing. In later log processing, they can present problems, so it is useful to be able to remove them before processing.
A Null value count for a curve is shown in the Information Panel after clicking on the curve name.
Examples of issues created by Null values;
- Functioning logs. For example, computing Acoustic Impedance AIMP = VELP * RHOB. If one of either the 2 input curves has a Null value, then output AIMP will be Null value. So in the worst case scenario, the number of Null values in the AIMP will be the sum of all the Null values in both the VELP and RHOB curves.
- Spatial filtering. If a single Null value is encountered, then a section of data equal to the filter length will be set to Null value as the filter passes over. For this reason, spatial filtering is terminated when a Null value is encountered.
- Log integration will fail. For example computing Integrated Transit Time (ITT).
- Log blocking and zoning will fail when Null values are encountered.
For these reasons, it is best to remove Null values before proceeding with any processing, Three methods for removing Null values follow.
The curve filtering algorithms have a Null value tolerance parameter. What this means is that if a sequence of Null values is encountered, but the number of Null values in that sequence is less than the tolerance, the sequence of Null values is patched over using the last good value. This will allow the filtering to continue. The default value for tolerance is 1 Null value.
Null values commonly occur at the start and end of logging data. So the best way to deal with these is to limit the depth of the dataset to exclude them This can be done in the "Copy a Dataset" process in the Log processing menu. Set the upper and lower depth to exclude the depths with Null value. This will act on all the curves in the dataset, but this is normally not an issue, since the other curves are probably also not giving representive values anyway at these depth extremities.
The third way of the handling Null values, is to use the Curve Editor discussed above and manually patch over them using the mouse and keyboard.
When preparing data for splicing, there are also good reasons to keep the Null values at the extremities of a log data. And to convert bad log values of other curves into Null value, so they have a lower order of precedence during splice. Setting section of a curve to Nulll value can be done in the Curve Editor
4.7 Merging and Splicing Data
These options are available from the Log Processing menu.
Log splicing is an advanced option that requires a passcode to activate.
Merging data. A new dataset is created that contains all the curves from both datasets. The start and stop depths of the new dataset will be the adjusted to include all the data in both input datasets. Null values are padded onto the extremities where no data was otherwise available
Splicing data. The two input datasets need to have some depth overlap. Ideally, the same curves should be present in both datasets. During splicing, all curves with the same name are found in each dataset, and are spliced together.
If a dataset contains multiple curves with the same name, then only first curve is spliced. So to avoid confusion, the datsets should be prepared beforehand by removing curves with repeated names.
If a curve only exists in one of the datasets, then it is still included in the splice, but is padded with Null values.
When two curves are spliced a default order of precedence for splicing is set. If one the curves to be spliced is Null value, the order of precedence is to the curve that has a real value.
Non aligned sample depths
One problem that arises when merging and splicing data, is when the sample depths do not align at the same values. Most log data will have the sample depths at a value that is an integral number of times the sample rate.
For example, 1490 metres divided by 0.1524 = 9776.9028, whereas 1490.0148 metres divided by 0.1524 is 9777, so the depth of 1490.0148 is an integral number of times the sample rate.
A 0.1524 m sampled depth sequence that includes 1490.0148 metres will also have 0.0000 m in the same sequence.
Splicing data and merging data when the depths do not exactly align (overlap) is not possible without shifting one of the inputs first.
If a dataset fails the criteria of non-integral times sample rate depth points, then it can be resolved by applying a Depth Shift of 0.0 m, and the select option to align sample depths to integral multiple of sample rate.
4.8 Saving all the data to a Project file
All the data that has been loaded into Well Log Viewer can be saved to project file.
The option to do this can be found in the Main menu under the File option. This saves the current internal database to a disk file, which can then be re-loaded for further analysis, re-processing and plotting at a later date.
The plot layouts are also saved in the project file, so the exisitng plots are automatically recreated.
Project files made with earlier versions of this software may not be supported. Backward compatibility is provided to the more recent versions.