Stratigraphy Model

Frequently, the geologist does the initial logging of the well and the hydrologist or hydrogeologist interprets these logs to come up with a coarser aggregation that lumps together the fine-scaled designations applied by the geologist. This interpreted geology is what is referred to as Stratigraphy in operation of EnviroInsite and what is plotted as Fence Diagrams or Geologic Models.

Three dimensional models can be constructed in EnviroInsite that are either open like a 3d fence diagram or closed to attain the visual appearance of a solid object. Both types of plots are generated by selecting 3d Model from the Stratigraphy drop-down menu. You will then be prompted to define the polygon along which the 3d geologic model will be constructed. By electing for a closed polygon a 3d solid object is created. For a 3d fence diagram, leave the close polygon check box open.

Fence diagrams and 3d geologic models are generated by interpolation of the contact elevation to the defining polygon. The vertical areas are then filled. For the case of a closed polygon, the surface is drawn by interpolating the contact elevation surface onto a regular grid.

Query

The query dialog box is similar to that used in other parts of the application. In this case however, you need to select the stratigraphic units to be plotted. Select units from the list box on the left and hit add to include them in the list of units to be plotted. The units should be in order from top-down of their appearance in the physical model. That is the uppermost units in the real world should be added to the list first followed by the other units.

Format

Interpolation

This tab allows the user to select the interpolation scheme and the parameters of the interpolation method. The correct selection of interpolation parameters is critical for generation of contours that accurately reflect the field data and our expectations of how the values vary between the measured data points. The default parameters are frequently adequate, although some improvement can be anticipated through trial and error.

Kriging Parameter

The kriging routines are derived from the kt3d routine of the Geostatistical Software Library (GSLIB) authored by Clayton Deutsch and Andre Journel (www.gslib.com).

The reference, GSLIB: Geostatistical Software Library and Users' Guide is highly recommended. Here are the spherical semivariogram models used by EnviroInsite for an isotropic system, where h is the lag, c is the sill, and a is the (practical) range. This is from this link to an introductory text on kriging: Click here for an introductory text on the variogram models

For anisotropic systems h/a in the previous is calculated as