L. Volume Calculations for Grids

Owned by Erlend Kvinnesland
Last updated: Sept 23, 2013
3 min read

Introduction

Volume calculation for one grid and an isopach or between two grids and optionally two contact planes does not require a layer model and can be done quite easy with a dedicated menu called Volume calculation that is directly visible on a grid. The volume calculation operates with singles values for the petrophysical parameters and singles values or grids for contact planes.

Exercises:


In the next exercise we are going to calculate HCPV volume between Upper Cretaceous and Base Jurassic in the layer folder for depth grids. The volume will also be between the contact planes 2500 and 2900 and within the license area.

Exercise

Calculate HCPV volume for a zone

  1. In the folder 04_Depth data / Grids Interpretation right click 03Upper Cretaceous and select Grid Operations > Volume calculation.
  2. Check in Apply a bottom grid in calculations.
  3. Browse in 05BaseJurassic in the 04_Depth data / Grids Interpretation folder as the bottom horizon.
  4. Set Type of volume to be calculated to Between plane1 and plane2.
  5. Check in Specify plane 1 level and set the value to 2500.
  6. Check in Specify plane 2 level and set the value to 2800.
  7. Check in Use area grid or outline and browse in 01_Cultural Licenses / Licenses / Licens 07-18
  8. Write in values for porosity = 0.4, water saturation = 0.5 and net to gross = 0.6.
  9. Click Execute to perform HCPV volume calculation.
  10. The result is: Volume calculated from 2500 to 2800: 133.72658 cubic km (E9)
Exercise

Display volume grids

  1. Select the Display tab
  2. Make sure combo box is set to As single volume and click Display calculated volume
  3. Click on Display calculated volume when the combo box is As single volume.

Take a look at the display

  1. Make sure the combo box is set to On bottom of grid and click on Display calculated volume.
  2. Set a cursor marker with y and click Get cursor values.
  3. Click Perform cross section from position value.

The result display is shown below


Volume grid and cross section displayed on bottom grid

Comments on Volume grid displayed on bottom grid

The picture shows the volume grid draped onto Base Jurassic. The grid is not present outside the area of positive volumes. In addition a cross section is displayed and shows clearly where there are no volume because the top grid is below the bottom contact plane. The cross section study illustrates that clearly.

Exercise

Display top and bottom grids and contact planes.

  1. Display the top and bottom grid from the project.
  2. Display the two contact planes.
  3. Mark with y a cursor position at the top plane and type the shell command: tx2 col red cur fol txt "GOC 2500"
  4. Mark with y a cursor position at the bottom plane and type the shell command: tx2 col gre cur fol txt "OWC 2800"


Top and bottom grids and contact planes


Exercise

Create a cube with top and bottom grids and contact planes.

  1. Click Create cross section cube.
  2. Click Activate frame and move the manipulator to see the cross section planes in red green and blue colors.
  3. Display the bottom horizon.

 


Cross section cube for gas, oil and water


Exercise

Calculate curve for area versus depth.

  1. Use exactly the same settings as in Exercise Calculate HCPV volume for a zone.
  2. Check in Calculate area or volume against depth.
  3. To calculate area / depth the combo setting is Calculation is done using: area.
  4. Push Execute
  5. The area / depth curve is saved in the project as 04_Depth data / Curves_area_depth 03UpperCretaceous_area_depth_curve.
  6. Display the area / depth curve by pushing Show curve. The screen is blanked and the area / depth curve is displayed. Instead of using the existing screen window a new window or a new Tab could have been established.
  7. Write the text Area / depth from 2500 to 2800 at top of the window. This is done most easily by clicking a cursor point (in 2D mode) at top left. Then go to the command shell and write: tx2 cur col bla txt "Area / depth from 2500 to 2800"
  8. The area / depth factor is set low to have the area numbers small. The real area numbers are multiplied by the factor.


Area versus depth between 2500 and 2800