Here the procedure to define a target normal compaction trend and the data input will be discussed. To that end in Mat_001d/Additional the spreadsheet 00_Material_Master_v02_Ss_Si_Sh_Ca.xlsx is provided to facilitate the visualisation of results and also to provide the suggested input values for the mechanical compaction models following our developed facies-mixture database presented in tutorial Mat_001c_Case02.

 

The mechanical compaction models use Athy or Schneider input properties, in conjunction with the remaining elastic, poroelastic and plastic input properties, to automatically calculate the corresponding hardening properties for use in the simulation. This is done internally and the user does not require to manipulate the hardening data. However when using the mechanical compaction models the code automatically outputs an .hdh file containing the generated hardening data in a sub-folder named Compaction for each of the materials in the simulation, thus enabling validation of the data in case the user is interested. The .hdh file is named as ModelName_MaterialName.hdh.

 

The suggested procedure is then as follows:

 

1.Define all elastic and poroelastic properties

2.Define the plastic properties relative to the yield and flow potential surfaces

3.Define the input values for the Athy or Schneider mechanical compaction trends

4.Define initial estimates for k0 and pc/p' ratio values during uniaxial consolidation (those values are required to compute the hardening data. For more info the user is referred to Mat_001c_Case01 ). The suggested ranges for the initial guess values are 05 - 0.85 for k0 and 1.03 to 1.12 for pc/p' ratio.

5.Run a single element k0 test and check the results in terms of predicted k0 and pc/p'

6.Update those input values in the material if required (see the final figure in Mat_001c_Case01 for a reference in the potential error in the predicted NCT compared to the target)

7.Run a column consolidation model to validate the results

 

This is demonstrated in the following examples. Note that only the input and output relative to the mechanical compaction models will be discussed. The files for the examples are provided in Mat_001d/Case01/Data. The following cases are undertaken:

 

•Case01a: Material defined using the Schneider model with optional-related parameters being defined in the data file.

•Case01b: Material defined using the Athy model (equivalent properties to Case01a). Only compulsory data is being defined.

 

For Case01a two simulation data files are provided:

 

•Mat_001d_Case01a_k0.dat which simulates a single element k0 test used to correct the initial k0 and pc/p' guess.

•Mat_001d_Case01a_cons.dat which simulates gravity consolidation in an initially 13 km high column over a long time period (hydrostatic pore pressure) to validate the obtained normal compaction trend.

 

For Case01b the consolidation data file is provided as the properties are equivalent to those in Case01a and we already corrected the initial guess values for k0 and pc/p'.

 

 

Case01a

 

The mechanical compaction data in Mat_001d_Case01a.mat is discussed below.

 

 

 

 

Case01b

 

The mechanical compaction data in Mat_001d_Case01b.mat is discussed below. This case demonstrates the minimal input required.

 

 

 

 

 

Results