You can also delete all depth calibration points by going to Edit>Delete All Depths. The screen will redraw once the marker is deleted. After selecting this tool, click the left mouse button on the depth marker to be deleted. Alternatively, go to Edit>Delete Depth on the menu bar. To delete an individual depth calibration point, click the ∽rop button on the Calibration Tool Bar. If the thin black calibration lines are off of the depths printed on the raster log, add new points or adjust your existing depth calibration points. If these black lines look close to the actual image, your calibration points are sufficient. Unlike normal red calibration lines, these cannot be moved they just show Petras scaling between your calibration lines. Petra also automatically scales and places reference black lines every 100. Most raster logs only really need a handful of points. The better the quality of the raster log, the fewer points necessary to depth calibrate the image. To edit the value of an existing depth, click on the depth calibration point with the right mouse button and enter a new value. To change the location of the depth, click and drag the depth calibration point using the left mouse button. Repeat the process for each new depth calibration point. After entering the depth value, the screen will redraw showing the new calibration depth point. You will be prompted for the depth value. Next, position the horizontal cursor at the depth you wish to pick and click the left mouse button. To create a new calibration depth, click the ∺dd button on the Calibration Tool Bar Alternatively, go to Edit>Add Depth Point on the menu bar. Only the log between the top and bottom depth calibration point can be digitized or shown on a cross-section. This process involves picking 2 or more depth calibration points from the image. To turn on this toolbar, go to View>Depth Calibration Toolbar on the menu bar.Īs mentioned above, Petra needs computer-recognizable depths to be assigned to depths printed on the log. Though most of the tools to calibrate logs are available from the menu bar at the top of the screen, the quickest and easiest way calibrate a raster log is to use the Depth Calibration Toolbar (highlighted in blue in the example above). The more group names in a project, the tougher it will be to display cross-sections later. When selecting or creating group names, its generally better to aim for fewer, more general group names rather than create many precise group names. Since the raster image is a resistivity log, add a Resistivity group. To add a new group, click the button next to the group names dropdown box (highlighted in red in the example below) or to Group>Add or Delete Groups. Select the appropriate image group from the "Image Group Name" drop-down list. It might be useful to use the zoom buttons ( ) on the upper right corner of the window to make the image larger or smaller.Īll raster images are assigned group names. A group name usually describes the log type (like Resistivity) and/or scaling (1, 2, or ∵) of a log image. By default, the D-122s raster log will be located here C:\geoplus1\Projects\TUTORIAL\IMAGES\D-122.TIF. Navigate to the specific image file and select it. Next, open an image file by going to File>Open Image on the menu bar. Notice that the selected wells UWI and name appear on the screen. This opens the ∼alibrate Log Image screen. In the Main Module, click on the ∺ssign/Calibrate button on the Rasters tab. To start calibrating a raster log, open the raster calibration screen. For this example, select the D-122 well in the Main Module. The first step to calibrating a raster is to select the correct well in the Main Module. Most commercial data vendors depth register their data, but images directly from scanners and state providers are not depth calibrated. Petra needs to know what part of the image corresponds to which depth in order to assign values during digitizing. Raster logs are scanned copies of paper logs saved as image files. This guide walks through depth calibrating and digitizing the GR curve on the D-122 well in the TUTORIAL project. Going from a simple image file to a digital log involves two major steps: depth calibrating the raster image, and tracing the desired log curve. Converting a raster log into a digital log is called digitizing. Digital logs have several advantages over raster logs: theyre more easily stored in Petras database, look great in a cross section, and can be calibrated and used in calculations. ![]() Digital logs, on the other hand, store log values in a form that is directly readable by a computer.
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