Creating Stratigraphic Diagrams - Overview
Use the tools in the Borehole Manager Stratigraphy menu to visualize your stratigraphic data (listed in the project’s Stratigraphy tabs) in a variety of ways: Create 2D maps and 3D images of stratigraphic surfaces and thickness, 2D stratigraphic profiles and sections sliced anywhere in the project area, “surface” maps of stratigraphy where it intersects a surface, plan maps or horizontal slices of stratigraphy at specific elevations, 3D stratigraphic fence diagrams, and 3D stratigraphic block diagrams.
We have already covered the surface and thickness maps back on page 97. In this section, we will discuss the remaining Stratigraphy menu tools.
If you don’t have stratigraphic layers entered into your project’s Stratigraphy tabs, you can use the Pick Formations tool (page 126) to record stratigraphic depths from elogs, raster logs or lithology logs.
Unlike lithology data, which represents observed rock types which can repeat in a borehole and be inconsistent in order, stratigraphic data represents organized formations, consistent in order between boreholes, and non-repeating. RockWorks uses surface modeling or gridding tools to illustrate the stratigraphic layers. Because surface models are created for these diagrams, you must have stratigraphic data for at least 4 boreholes.
“Straight” sections and fences are also offered, in which straight line correlations are drawn between adjacent boreholes and no surface interpolation occurs.
Notes:
Formation names and the colors and patterns to be used to represent them are listed in the project’s Stratigraphy Type Table (see page 237).
See Missing Formations (page 59) for tips on how to enter your stratigraphy data.
The program will create grid models of the surfaces and bases of the formations listed in the Stratigraphy tabs, storing the models on disk. The grid files will be assigned names in the background based on the formation: "formation_top.grd" and
"formation_base.grd". Two grid models will be created for each formation.
Un-check the Interpolate Surfaces check-box if the grid models already exist in the project folder and don’t need to be interpolated again. This can be a handy way to include GRD files that are the result of editing/filtering/other operations (page 151).
Creating a Stratigraphic Model
Use the Borehole Manager's Stratigraphy / Model tool to create a 3-dimensional surface diagram that illustrates stratigraphic layers. The stratigraphy layers will be color-coded based on the formation's background color in the Stratigraphy Type Table.
This process involves the interpolation of a grid model for the upper and lower surface of each of the stratigraphic units using the user-selected gridding method. These grid models will be stored in the project folder.
The completed diagram will be displayed in a RockPlot3D window, with formation upper surfaces, lower surfaces, and side panels. Volume and mass of each formation will be displayed in the RockPlot3D window.
The program offers optional creation of a 3D solid model representing the stratigraphy grid models layered from the bottom up, for use with other analysis tools.
Notes:
!
Insert a check in the Save Model option if you want the program to store on disk a numeric 3-dimensional solid model, with voxel nodes representing stratigraphy type.Use a “.mod” file name extension.
RockWorks will not use this MOD file when displaying the stratigraphic surfaces in RockPlot3D at this time; it will instead display the grid surfaces. But, you may still want to store the model on disk for later filtering, volumetric computations, etc., and later 3D display with the RockWare Utilities Solid menu tools.
If you have requested a stratigraphic solid model, it will be initialized using the current project dimensions. RockWorks will then "insert" each formation’s surface into the solid model, by assigning the voxel the integer "G" value listed in the Stratigraphy Type Table. The program will store this stratigraphic solid model file on disk using the file name you requested. You can use this for volume computation (page 128).
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Creating 3D Stratigraphic Models and Diagrams.
Creating Stratigraphic Profiles
Use the Borehole Manager's Stratigraphy / Profile tool to create a 2-dimensional (flat) vertical profile of a multiple stratigraphic layers read from the Stratigraphy data tabs, between any two points in the study area. The profile layers can be color- or pattern-filled. During the process of building the profile, the program will create a grid model for
each of the active stratigraphic layers using the user-selected gridding method. Striplogs can be appended, and a map of the profile location can be created automatically.
Notes: See page 145 for information about drawing the profile slice.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Profiles &
Sections / Creating Stratigraphy Profile Diagrams.
Creating Stratigraphic Cross Sections Modeled Sections (Grid-Based)
Use the Borehole Manager's Stratigraphy / Section / Modeled tool to create a 2-dimensional (flat) vertical multi-panel profile of a multiple stratigraphic layers read from the Stratigraphy data tabs, between multiple points in the study area. The panel endpoints can be anywhere within the project area – they don’t need to coincide with borehole locations. The section’s layers can be color- or pattern-filled, and striplogs can be appended. During the process of building the section, the program will create a grid model for each of the active stratigraphic layers using the user-selected gridding method.
See the next topic for creating “straight” sections using no interpolation. Logs can be appended, and a map representing the section location can be created automatically.
Notes: See page 147 for information about drawing the section slice. For display of multi-paneled grid-based sections in 3D, see Modeled Fences on page 124.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Profiles, Sections and Fences / Creating Interpolated Stratigraphy Sections (Multi-Panel).
“Straight” Sections (No Interpolation)
Use the Borehole Manager's Stratigraphy / Section / Straight tool to create a 2-dimensional (flat) vertical multi-panel profile of a multiple stratigraphic layers read from the Stratigraphy data tabs, between multiple points in the study area. The panel endpoints must coincide with borehole locations. The section’s layers can be color- or pattern-filled, and striplogs can be appended. Unlike the Modeled section, the Straight section
correlations will simply be drawn as straight lines between like formations in adjacent boreholes. See the previous topic for creating “modeled” sections based on grid surfaces.
Sections can be hung on a specified stratigraphic unit; see below. A map illustrating the section location can be requested.
Notes: See page 147 for information about drawing the section slice. For display of multi-paneled straight sections in 3D, see Straight Fences on page 124
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Profiles, Sections, and Fences / Creating Interpolated Stratigraphy Sections (Multi-Panel).
Creating Stratigraphic Fence Diagrams Modeled Fences
Use the Borehole Manager's Stratigraphy / Fence / Modeled and Fence (ESRI-Format) / Modeled tools to create a 3-dimensional fence diagram that illustrates stratigraphic layers, for output to RockPlot3D or to an ESRI Shapefile format.
Fence panel spacing can be regular (in a variety of configurations), or you can draw your own panels. The stratigraphy will be color-coded based on the formation's background color in the Stratigraphy Type Table. During the process of building the fence panels, the program will create a grid model for the upper and lower surface of each of the active stratigraphic layers using the user-selected gridding method.
3D striplogs can be appended, and a map illustrating the fence panel locations can be requested.
Notes: See page 148 for information about drawing the fence panels.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Profiles, Sections, and Fences / Creating Interpolated Stratigraphic Fence Diagrams.
Straight Fences
Use the Borehole Manager's Stratigraphy / Fence / Straight and Fence (ESRI-Format) / Straight tools to create a 3-dimensional fence diagram that illustrates stratigraphic layers, for output to RockPlot3D or to an ESRI Shapefile format. Unlike Modeled fences, above, the Straight fence correlations will simply be drawn as straight lines between like formations in adjacent boreholes.
Fence panel spacing can be regular (in a variety of configurations), or you can draw your own panels. For these hole-to-hole fences, the panels will be snapped to the closest borehole. The stratigraphy will be color-coded based on the formation's background color in the Stratigraphy Type Table.
3D striplogs can be appended, and a map illustrating the panel locations can be requested.
Notes: See Missing Formations (page 59) for tips on how to enter your stratigraphy data.
See page 148 for information about drawing the fence panels.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Fence Diagrams / Creating Hole to Hole Fence Diagrams.
Manually Building 3D Stratigraphic Fences
Use the RockWare Utilities Grid / Grids -> Stratigraphic Fence tool is used to create a stratigraphic fence diagram based on a list of existing grid models that represent the top ("superface") and base ("subface") of each unit. These are grid models that must already
exist on your computer. You may request regular fence panel spacing, in a variety of configurations, or you can draw your own panels.
This program is designed for two types of applications:
Users who have created their grid models within other applications (e.g. ModFlow, Surfer) and wish to use RockWorks to create stratigraphic (or hydrostratigraphic) fence diagrams.
Users who have created their grid models within the Borehole Manager portion of RockWorks but need more flexibility in dealing with stratigraphic relationships (e.g.
special manipulations with the grids).
This is a “manual” way of creating the kind of stratigraphic fence that’s available in the Borehole Manager’s Stratigraphy / Fence tool.
Datasheet: RockWare Utilities. This tool reads a “stratigraphy gridlist” data file (page 78).
Notes: Be sure the grid models that are listed in the datasheet actually exist in the current project folder. Use the “cutoff” setting to erode thin layers. See page 148 for information about drawing the fence panels.
Help / Contents / Working in the Borehole Manager/ Grid Model Tools / Stratigraphic Tools / Manually Building 3D Stratigraphic Fences.
Creating Stratigraphy-Based Geology Maps
Use the Stratigraphy / Surface Map tool to create a 2-dimensional map representing the stratigraphy where it intersects a designated surface, typically the surface topography. In other words, it creates a geological map based on downhole stratigraphic data. The process involves creating a stratigraphic model for the study area, storing it as a temporary solid model (MOD), and determining the intersection of the different formations with a user-specified surface model. This is stored as a RockWorks grid model (GRD), and the map is displayed in the RockPlot2D window.
Notes: Be sure the stratigraphic names are correctly defined in the current Stratigraphy Type Table (page237). You need to be sure, also, that the dimensions and node density of the grid model and the solid model are the same. See Missing Formations (page 59) for tips on how to enter your stratigraphy data. Use the RockPlot2D Export / RockPlot3D tool to drape the surface stratigraphy map over a grid model and display it in 3D (as in the image above).
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Creating Stratigraphy-Based Geology Maps.
Creating Plan-View Stratigraphy Maps
Use the Stratigraphy / Plan Map tool to create a 2-dimensional map representing the stratigraphy along a horizontal slice, at a specified elevation. This is stored as a RockWorks grid model (GRD), and the map is displayed in the RockPlot2D window.
Notes: Be sure the stratigraphic names are correctly defined in the current Stratigraphy Type Table. See Missing Formations (page 59) for tips on how to enter your stratigraphy data.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Creating Stratigraphy Plan-View Maps.
Manually Building 3D Stratigraphic Diagrams
The RockWare Utilities Grid / Grids -> Stratigraphic Model tool is used to create a 3D stratigraphic model diagram based on a list of existing grid models that represent the top ("superface") and base ("subface") of each unit. These are grid models that must already exist on your computer.
This program is designed for two types of applications:
Users who have created their grid models within other applications (e.g. ModFlow, Surfer) and wish to use RockWorks to create stratigraphic (or hydrostratigraphic) diagrams.
Users who have created their grid models within the Borehole Manager portion of RockWorks but need more flexibility in dealing with stratigraphic relationships (e.g.
special manipulations with the grids).
This is a “manual” way of creating the kind of stratigraphic model that’s available in the Borehole Manager’s Stratigraphy / Model tool.
Datasheet: RockWare Utilities. This tool reads a “stratigraphy gridlist” data file (page 78).
Notes: Be sure the grid models that are listed in the datasheet actually exist in the current project folder. Use the “cutoff” setting to erode thin layers.
Help / Contents / Working in the Borehole Manager/ Grid Model Tools / Stratigraphic Tools / Manually Building 3D Stratigraphic Diagrams.
Picking Stratigraphic Contacts
Use the Borehole Manager’s Stratigraphy / Pick Contacts tool to determine depths to stratigraphic tops (and bases) from geophysical, raster, lithology, or other log data.
This is one of the most powerful tools in this program since it lets you visualize existing lithology blocks or geophysical curves in a 2D display, and then point-and-click to pick
the stratigraphic contacts. The contact depths are recorded in the project’s Stratigraphy tabs.
! This tool will assign formation depths assuming vertical boreholes. If your boreholes are deviated, you may need to eventually edit by hand the picked formation depths, based on how the stratigraphic surfaces or log intervals look when displayed in diagrams that can accommodate the borehole’s deviated downhole trace.
We encourage you to follow very carefully the steps listed in the How To section of the Help messages which are summarized below.
1. Enter your known data: Typically this would be lithology intervals down the hole, or geophysical (elog) measurements.
2. Build a log section: This is not required, but it’s helpful to be sure your data is good, for setting up the proper section alignment, for viewing the known data to be picked from, and for determining the formations that are present.
3. Create a Stratigraphy Type Table: With a good idea of the look of the existing downhole lithology or geophysical data, you need to create a "Stratigraphy Type Table" which lists the names of the formations, from the surface downward, that are represented in your project.
4. Set up the formation picker display: This should be set up just like the hole to hole section in step 2.
5. Pick the wells to be displayed: You can choose the same boreholes as were chosen in step 2, or pick a new selection of wells.
6. Pick the first formation in the Contact Picker window: Select the name of the formation to be recorded and left-click on each log where that formation’s top is displayed. The program will record the depths in the table. Right-click on each log at the formation’s base, and these will be recorded.
Note that you can add formation names to the Stratigraphy Type Table while you are in the Contact Picker window.
7. Pick the next formations: Select the name of the next formation to be recorded, left-click to pick tops and right-left-click to pick bases. Continue in this manner for additional formations.
8. End the session: Click on the Exit button and discard, save, or adjust-and-save changes.
What next? Now that you have the stratigraphic units defined, use the Stratigraphy / Model tool to create a 3-dimensional solid model of the units. The Stratigraphy menu also offers display of structural surfaces, thicknesses, profiles, sections, fences, and plan-view and stratigraphy surface maps. Create 3-Dimensional log displays of the borehole data, and append them to the stratigraphic model.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Picking Stratigraphic Contacts.
Creating a Stratigraphic Volume Report
Use the Borehole Manager’s Stratigraphy / Volumetrics tool to read a saved stratigraphic solid model and compute the total volume or mass for each stratigraphic layer as a function of the relative depth/elevation. The resulting computations are displayed in the RockWare Utilities datasheet.
Input: This tool reads data from an existing stratigraphic solid model (MOD file) created if Save Model is checked in the Stratigraphy / Model menu item (page 124).
Output window: RockWare Utilities datasheet Notes:
You can select from the following results: Nodes, Volume, Mass, or Percent.. Nodes reports the numbers of nodes of each stratigraphic type at each elevation slice.
Volume will be reported in cubic units (typically meters or feet, depending on your X, Y, and depth/elevation units). If you select the Mass option, these computations are based on the Density Factor declared in the current Stratigraphy Type Table which declare mass per cubic unit. Percent represents the percent volume of each stratigraphy type at each elevation level. Multiple units can be selected.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Creating a Stratigraphic Volume Report.
Exporting Stratigraphy Data
Use the Borehole Manager's Stratigraphy / Export tool to export stratigraphy depth, elevation, or thickness data for each borehole to an ASCII (Text) XYZ file. The resulting file will contain the X and Y location coordinates for the formation contact in each borehole (taking into account any boring deviation or inclination), and the selected depth, upper elevation, lower elevation, or thickness. (Thickness is drilled thickness, as recorded in the Stratigraphy tab, not grid-based thickness.) This file can be imported into the RockWorks RockWare Utilities datasheet or into other applications, or opened automatically into the default Windows text editor (such as Notepad).
Output window: ASCII XYZ file representing observed depth, upper elevation, base elevation, or thickness.
Notes:
To load this exported file into the RockWare Utilities datasheet, follow these steps:
Click on the RockWare Utilities tab, choose File / New Datasheet, select the
"Generic XYZ" format for the layout, and use the File / Import / Into RockWare Utilities / ASCII option to import the text file into the data window.
Help / Contents / Working in the Borehole Manager/ Stratigraphy Tools / Exporting Stratigraphy Data.