Depth Shift 

The depth shift application allows the user to define multiple shift definitions interactively on the screen in any order.  The results of the definitions may be reviewed on the screen and additions or deletions made until the proper definitions have been made.

1.Open the database file to be edited.

2.From HDSlog Main Menu select Data Editing then select Depth Shift from the dropdown.

The depth shift screen appears. It is made up of four panels.

•The Input Data and Interpolation Method  panel (1) is where the user enters a curve which is on depth, a curve which may be off depth, companion curve(s) and a second on depth curve. And, the Interpolation Method to produce a shift is also selected here.

•Curve List  panel (2) contains all the curves in the database file.

•Defined Depth Shifts and Depth Range panel (3) is a spreadsheet with all the Depth Shifts. The first column is the original depth, the second is the new depth and the last column is the difference between the first two.

•Log Shift Comparison Plot (4) is where the companion log, edit log and shifted log are displayed.

3.Select On Depth curve.

In the Input Data panel populate an On depth curve by clicking the box and selecting the curve  from the Curves List panel. Normally this is the first logging run and a Resistivity measurement.  This is the Reference curve and appears in the second track in the display plot.

4.Select an Off Depth curve in the same manner as On Depth curve from the Curve List panel.

This curve has similar bed response to the curve to be adjusted. This appears in the third track in the display plot.

5.Select Companion curve(s).

These curves may be items such as the caliper, density correction, etc. which may prove useful in making judgments in the quality or response of the data that is being reviewed. These are displayed in the first track in the log shift comparison plot.

6.Adjust the scale of the plot to attain a clear visibility of the peaks.

Click on the scales at the top of the first track. When the following screen opens, enter the Left and Right Scale values, change the plot color and adjust other values, if desired. Then click the Accept button in upper right. Then close the screen.

TIP:  To zoom the data click on any two point in the depth track.  The log track will redraw to the scale of the two points.  The legend of the Depth Track will be in Yellow and display Zoomed.  A scroll bar will be on the right side of the right track.  Use the scroll button to scroll through the data.   To un-zoom the data click in the Yellow area.  The display will return to Full Data Range.

7.Define Depth Shifts.

Several functions for defining the depth shifts are available from the toolbar. The default is Drag Over Correlation. Each is described below:

•Drag Over Correlation:  Drags the edit curve to the reference curve.  After the user selects this function, the Define Shift button is clicked to activate it. To move the curve, select it with the mouse and press the left mouse button. Then, drag the curve to the desired location. Once the curve is in the desired location, release the left mouse button to initialize the shift. If manual shift is selected, the Update button must be used to review the results. The shift procedure only changes the depth reference.

•Two Point Correlation (with Mouse): When this function is selected, the mouse cursor will change to a crosshair (+) when the mouse is over the editing track (Track 2). To make a definition, click the mouse on the edit curve then, click the mouse on the desired depth of the reference curve. A line will connect the two points. The change is displayed in Track 3 after the screen update.

TIP: It is Not necessary to click exactly on the curve value! However, it is necessary to click exactly on the curve depth!

•Two Point Correlation (with Keys): When this function is selected, an arbitrary blue line is placed in the middle of the data. To set the depth definitions, use the Up and Down arrow keys on the keyboard to move the line. If the Shift key is help down in conjunction with the arrow keys, then the line will move 10 depth increments per key stroke when the mouse is over the editing track (Track 2). To make a definition move the line to the desired depth on the edit curve, press the Space Bar then, move the line to the desired depth of the reference curve and press the Space Bar. A line connects the two points. The change is displayed in Track 3 after the screen update.

•Auto Shift:  This function performs a depth shift on the entire file using the coefficient of correlation.  When activated another screen opens and that prompts the user for making additional selections:

ØWindow Length:  Sets the depth dimension for the program to scan above and below every depth in the file.  This number can be set as a measurement of feet or meters or as the number of increments.  Increments refer to the total number of depth records. 

ØMax Shift: Puts a maximum limit on the distance of any shift definition.  It is set as depth measurement or increment.

ØDo Autoshift: Performs the automatic depth shift routines.

TIP: HDS recommends performing Curve Smooth prior to the Auto Shift function.

Once the task is completed, the interactive Auto Correlations Results screen opens:

The results represent the amount of shift in the depth interval. The colors represent the quality of the correlation where: green is a good correlation; yellow is an average correlation and; red is a poor correlation.

The poor or average correlations can be removed by clicking in the cell adjacent to the specific correlation title or from the Defined Depth Shifts and Depth Range Panel.

The screen automatically updates the Log Shift Comparison Plot and the Defined Depth Shifts and Depth Range panel and the color coding is consistent on both.

Other toolbar functions are available to make the job easier. These include:

•Top Locked or End Locked: When the editing screen is first shown, 2 depth shifts are already define:

          1) Zero shifts at the top of the data (shallowest depth)

          2) Zero shift at the end of the data (deepest depth)

This method is used, as it may be very difficult to define points at the end data values using the mouse.   If you want either the top or end to be block shifted along with the closest definition, click on TOP LOCKED or END LOCKED and it will be toggled.  These functions may be toggled any time while working with your data.          

•Zero Shift: This function allows the user to select a depth and no shift definition placed in the list of shifts.  This is much easier than attempting to click the mouse twice without making any movement.  After the definition, the system changes back to the standard mode of operation, which requires two depths to be defined for each definition.

•Repeat Shift:  If the user has defined a depth shift, such as +1.5 feet at 1028, and clicks this function, the next depth selection with the mouse will result with another 1.5 feet shift at that different depth.  This allows the user to precisely define a block shift over a selected range.

•Last (Undo):  Deletes the last definition.  This is only allowed once?

•Select (Undo):  This function allows the user to select any defined shift and delete it from the definition list.  There is no restriction to the order of deletion.  The function is active until another edit function is selected.  To proceed select the toolbar button then click on the shift definition (x) in the second track.  The shift is removed and the result curve is updated.

•All (Undo):  If the user is unsatisfied with the definitions made, this function allows starting over.  No previously defined shifts are retained.

8.Once the depth shift is completed, process the shift changes by clicking "Save Shifts" from the toolbar.

Save Shifts only saves the Defined Depth Shifts and does not apply the depth shift to the curves yet. The application commences the depth shift process and writes another version of all depth shifted curves.

9.Now, select all the desired curves that need to be shifted, and  click the “Save to database” button to apply them. A report is written to the Process History file.

10.Exit

Direct Manual Editing:  the middle table of information is available for use in defining/refining specification.  The Depth Shift Specifications list all of the depths, which were interactively selected.  If you wish to refine the depths, select the value and type in the value you wish.  The database will be checked and the closest actual depth displayed (this is important for the depths which were originally defined in Feet and converted to Meters).  If the value is out of range, the user will be given and error message with the type of error found.  When you return to the graphic curve display, the information will be updated.

Recalling Depth Shift Specifications:  A previous set of Depth Shift definitions can be recalled under the File options as Open Old Shift File.  The specifications that you have defined for use are in the file documentation and archived.  You may recall a previously saved set of specifications and apply them again.  This is a handy feature if one of the curves in a tool suite was overlooked when the others were depth shifted, or perhaps additional curves were loaded at a later time.  As depth shift specifications do not apply from well to well, the depth range of a file being read into the system is checked to assure the specifications are not out of range.  After a file is read in, the graphic screen and Depth Shift Table will be updated.  The Top and Bottom Locked buttons will be set to reflect the data read in.  The specifications read in can be edited in the same manner that interactively defined specifications are defined and deleted.