One of the highlights of our 2019.2 release of GVERSE Geophysics is a new interpretation data type: geobodies. A geobody, generally speaking, is a distinct, small-scale subdivision in subsurface data with similar seismic characteristics. GVERSE Geophysics 2019.2 provides the tools to isolate and extract geobodies in your data and use them in your analysis.
How do you go about it? Well, everything you need to start working with geobodies is found in the new Geobodies tab of our ribbon. Here, you can create and manage geobodies, choose your picking mode and then generate the body by either interpolating your picks or extracting it automatically from seismic. You can also make volumetric calculations to estimate the volume enclosed by the geobody.
We have a couple of different ways to create a geobody. The first is a simple interpolation of your seed picks. We take all your seeds picks and interpolate them to create an approximation of your geobody. One of the most common uses where interpolation works well is channel picking. You can view a video showing the channel picking capabilities here
The second method, the subject of this blog, is to track the geobody through the seismic volume. All you have to do to extract a geobody automatically is to identify the starting point(s) and define an amplitude threshold range of the data volume you want to use for the geobody extraction. The tracker will find all amplitudes in the threshold range connected to at least one of the initial seed picks. In a matter of a few clicks, you have your geobody – ready to be used in your analysis.
In the example here, there is a significant bright spot in the average energy volume for this inline. To track this and save it as a geobody, mark a few points using the Brush Pick mode. Use the brush to paint over the region of interest. The painted area is all considered as the initial seed for tracking the geobody.
You don’t have to be very precise when making seed picks for amplitude-based geobody extraction. Even if you’re a little sloppy around the edges, use the histogram to exclude amplitudes that you don’t want included in the geobody. To define the threshold, use the min and max sliders on the data distribution histogram. This histogram is the combined distribution of amplitudes covered by all seed picks on all sections for this geobody. Anything that falls outside this defined amplitude range is ignored during tracking. Click “Generate” and all samples that are connected to the initial seeds and have amplitudes that fall within the defined range are used to create the geobody.
Once you have the geobody, whether through interpolation or tracking, you can draw data from any seismic volumes available in your interpretation. From the “Display Settings” choose the “Seismic” option as the display type. It defaults to the data version used to generate the geobody. But, you can pick any available data version, and data from that volume will be draped on the geobody. In this example, I am drawing data from the amplitude volume to see how the actual seismic looks like on the geobody I extracted using the average energy volume.
I can also display a geobody as an intersection with vertical or horizontal seismic sections. Use the “On Section Only” option in the display type to view how the geobody intercepts a plane (inline, crossline or timeslice). This helps me understand the spatial and temporal extents of my geobody at a particular inline or crossline location or a constant time/depth.
Finally, you can calculate an estimate of the volume enclosed by the geobody. In time-domain interpretations, we must provide a way to convert the time values to depth. You can do this by using the active velocity model to get the velocity values required for the conversion. Alternatively, if you have a good idea about a representative velocity value for the geobody, you can also use the constant velocity option and provide a hard value for the velocity of the entire geobody. You’re not limited to a single calculation for any one geobody. You can use different velocity models or a series of different constant velocities for your calculation. Calculation history is saved as part of your interpretation and is always visible in the volumetrics window whenever you access it using the “Volumetrics” button in the Geobodies ribbon.
Geobody picking is a powerful new addition to the GVERSE Geophysics set of tools. We hope you will find this, along with the host of other new features that we have introduced in the 2019.2 release, useful when interpreting your seismic data in GeoGraphix.
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