Вычисление объема между двумя поверхностями

A common problem solved with a volume calculation is determining the volume of material between two grid files. For example, you might have drill hole data that provides the elevation of the top and bottom of a coal seam, and you want to determine the volume of coal. The elevation of the top and bottom of the coal seam can define the upper and lower surfaces, respectively. In this case, the lower surface would be entirely below the upper surface.

1. Create grid files of the upper and lower surfaces. In the example here, the grid files would define the elevation of the top and bottom of the coal seam. Both grids must use the same dimensions, and same number of rows and columns.

2. Choose the Volume command from the Grid menu. Specify the grid file for the upper surface in the Open Grid dialog box and click OK. The Grid Volume dialog box is displayed.

3. In the Upper Surface group box, click the Grid File option button.

4. In the Lower Surface group box, click the Grid File option button and then click the Browse button. In the Open Grid dialog box, select the grid file for the lower surface and click OK.

5. In the Grid Volume dialog box, verify that the correct grid files are specified for the upper and lower surfaces and click OK. An Editor window is automatically opened and the volume and area calculations are reported. The volume between the surfaces is reported as the Positive Volume (Cuts), which in this case is the same as the Volume calculation.

6. To save the information in a text file, click the Save As command from the Editor window File menu, specify the name to use as the text [.TXT] file, and click OK. The VOLUME COMPUTATIONS log is saved in the text file.

Calculating the Volume of a Lake

You might have a grid file that defines the bottom of a lake, and you want to determine the volume of water in the lake. In this case, you can use the lake grid file and a horizontal planar surface to determine the volume of water in the lake.

1. Create the grid file for the lake. If you have the lake bottom defined as depth of water, you should use negative Z values so the lake appears as a basin rather than a hill. It is also recommended that you add data points beyond the limits of the lake shore, so the surface is above the level of the lake in these areas.

2. Choose the Volume command from the Grid menu. Specify the grid file for the lake in the Open Grid dialog box, and the Grid Volume dialog box is displayed.

3. In the Lower Surface group box, click the Grid File option button.

4. In the Upper Surface group box, click the Constant option button. Type the value for the lake surface in the Z = edit box. For example, if you are using depth, the Z = value should be zero.

5. Click OK and an Editor window is automatically opened and the volume and area calculations are reported. The volume of the lake is reported as the Positive Volume in the Volume report.

6. To save the information in an ASCII text file, click the Save As command from the Editor window File menu, specify the name to use for the text [.TXT] file, and click OK. The VOLUME COMPUTATIONS log is saved in the text file.