Calculating fault transmissibility

As described in Fault permeability calculation methods, tectonic re-distribution of clay controls fault permeability. This geological variable (and fault thickness) are calculated in the Fault Seal Modeling workflow for input to fault transmissibility calculation (the preferred workflow to determine fault transmissibility). With the Fault Tansmissibility form (model > Fault Seal > Fault Seal Modeling > Fault Transmissibility) you calculate fault transmissibility (Tf) based on the connection area, fault permeability and fault thickness (as calculated with the previous steps of the workflow). The calculation is done for each 'calculation point' (i.e. the center point of the common area of any two cells which are in touch across a fault) according to the formula below (in SI units). This generates lateral variability in Tf values, that are constrained by the geological property grids and fault geometries in the model:

where:

Tf = Fault transmissibility (m3)

A = Connection area between any two cells which are in touch across a fault (m2)

Kf = Fault permeability (m2)

tf = Fault thickness (m)

 

On the Fault Transmissibility form you can choose to apply a Fault Transmissibility Multiplier (FTM) with which you can manually increase or decrease the geologically calculated fault transmissibility. When you select the Fault Seal Model as input in reservoir simulation with IMEX, GEM, STARS, ECLIPSE and tNavigator the final fault transmissibility (FTM * Tf ) is added to the cell to cell transmissibility as follows:

where:

CTRtot = Total transmissibility (m3)

CTRno fault = Cell to cell transmissibility (m3)

FTM = Fault transmissibility multiplier (unitless) - optional/extra parameter on the Fault Transmissibility form

Tf = Fault transmissibility (m3) - calculated based on grid properties

To calculate fault transmissibility

  1. In the Model drop-down list, select the Fault Seal Model for which you want to calculate fault transmissibility.
  2. In the table on the form, the faults as assigned to the Fault Seal Model are listed; per each of these faults, you can optionally apply an additional, unconstrained (grid independent) fault transmissibility multiplier (FTM) to manually increase/decrease the geologically constrained fault transmissibility Tf. To do this, enter the multiplier in the Multiplier column of the table. The FTM is handled in the reservoir simulator as explained above. When you do not want to apply a multiplier, enter 1 (no increase/decrease of Tf).
  3. Click Apply to calculate the fault transmissibility. Upon clicking:
  • The property 'Fault transmissibility' is added to the respective point set(s) in the 'Fault Seal' surface set in the JewelExplorer. You can visualize the property in the 3D View. Use the filtering option to hide the undefined values in the point set for better visualization. To do this, open the Object Inspector for the Fault transmissibility property. In the Object Inspector pane, switch off the Undefined checkbox (and click Apply if filtering update is not set to 'Automatic' at the base of the pane). For more on filtering with the Object Inspector, see Using the Inspector.

    • Important   The output property 'Fault transmissibility' in the JewelExplorer is the calculated fault transmissibility without multiplier, i.e. Tf, not FTM*Tf.

  • The Fault Seal Model is now ready to be selected as input to the reservoir simulation workflow with IMEX, GEM, STARS, ECLIPSE and tNavigator.