Example Flow: Building a 3D Property Model

This Flow demonstrates how to build a 3D property model that combines your well log data and structure grids to build a 3D representation of your data.

Prerequisites for this Flow include:

1. Writing Petrophysics Curves (Example Flow)
2. Generating Structure Grids (Example Flow)

If you have not yet done this, please do so, using the Example Flows referenced above as guides.

This Flow utilizes the following tools:

• LogInput >> Bring the log data into the Flow
• LogsToVolume >> Incorporates the structure grids and generates the volume
• BrickOutput >> Writes the 3D volume

In the LogInput you should select a log database that contains the curves you would like to use for the 3D models. In most cases this should be a database generated using a Flow similar to the example Flow for writing petrophysics curves (see link above).

Next in the LogToVolume tool you will select your structure grids, select the zones (in stratigraphic order from shallowest to deepest) that you would like to use in the modeling. Note that this will often be a subset of your overall stratigraphic section.

You will choose the Curve to grid - you can type the name of any curve into the selection box. You will then select the Interpolation method and any associated parameters.

One of the trickiest options is to choose the spacing. Click on the linke to "Intialize grid from giles" and consider selecting a SegY, another volume, or a well header database. The Inline and Crossline spacing controls the X/Y resolution of the model.

We recommend starting with coarse spacing (e.g., 1000x1000) for a first run so that the job will complete quickly, allowing you to evaluate the overall results before investing more time into higher resolution runs.

In the screenshot below the inline/crossline spacing is 100 feet - this means that for the area of interest we'll have 1094 inlines and 510 crosslines.

In this screenshot I have reduced the resolution to 500x500 foot spacing. This significantly reduces the total number of inlines/crosslines and allows the volume to be generated in under 2 minutes instead of taking ~10 minutes with the previous setup.

The final options are th Top/Base elevation (in TVDSS) and the number of elevations and stratigraphic samples. The top/base elevation define the vertical extents of the model. The number of elevations defines the vertical resolution. Example:

Top elevation = -1000

Base elevation = -5000

Number of elevations = 400

Vertical resolution = abs(base-top)/n_elevations

Vertical resolution = abs(-5000 - -1000)/400 = 10' vertical resolution.

The stratigraphic depth samples is used by the tool to createe an internal volume where all geologic zones are "flattened." It treats the earth as a stack of proportional layers rather than absolute depths. This can be visualized with an example:

The Flow ends with a BrickOutput that writes the resulting .vol file. Note that .vol files and be manipulated using the same interactions as a .map file!

Tips and Tricks

• Remember to write the petrophysics curves to a database ahead of time.
• Consider starting small and with lower resolution - this will allow you to test your model setup without investing large amounts of time.
• With respect to structure grids, start with a "less is more" approach and consider starting with only major zones and then adding in complexity as required.