Case3 Restoration with decompaction (synchronous)

 

 

The data file for this exercise is located in Rest_001/Exercices/Case3/Data. Look for ! TODO  text in the datafile and follow the instructions.

 

In this exercise a decompaction law to a prescribed porosity trend will be considered. This will be achieved by:

1Defining geostatic data to prescribe an initial porosity trend vs depth in all formations. Here the same porosity trend as in the tutorial example Geost_001_Case1 is adopted.

2Defining the decompaction model and properties in Material_data. The same porosity trend used for geostatic will be used for decompaction.

 

 

Initial porosity definition

Data File

 

 

* Geostatic_data            NUM=1

! ---------------------------------

 Groups   IDM=4

   "formation1"

   "formation2"

   "formation3"

   "formation4"

 Porosity_spatial                         1

 Pore_pressure_distribution   "Hydrostatic"

 

 

* Spatial_variation_definition NUM=1

! ---------------------------------

 Description     "Porosity vs. Depth"

 Type                      "Absolute"

 Distribution       "Depth_dependent"

 Variation_assignment              1

 

 

* Spatial_variation_values     NUM=1

! ---------------------------------

 Description   "Normal Compaction Trend"  

 Time                                0.0

 Values_vs_depth           IDM=35  JDM=2

  /Depth/     0        179.3    ...   6097.4

  /Porosity/  0.48834  0.44717  ...   0.039523

 

1The initial porosity trend for the four formations is prescribed using geostatic data.

2Full description is provided in Geost_001_Case1.

 

 

Decompaction definition

Data File

 

 

* Material_data                    NUM=1  

! ---------------------------------

 Material_name                  "Elastic"

 Units IDM=4

  /Stress/            "MPa"

  /Length/              "m"

  /Time/               "Ma"

  /Temperature/   "Celsius"

 Isotropic_elastic_properties     IDM=2

  /Young's Modulus/              50000

  /Poisson's Ratio/               0.20

 Grain_density                     2760

 Grain_stiffness                  30000

 Porosity                          0.50      

 Singlephase_fluid                    1

 Decompaction_Type                    1

 Decompaction_spatial                 1

 Decompaction_properties          IDM=1

  /Maximum porosity inc/         0.001  

 

 

1The Material_data is modified to include decompaction following a prescribed porosity vs depth trend during restoration (Decompaction_type=1).

2The porosity trend defined in Spatial_variation_values NUM=1 is assigned to perform decompaction (Decompaction_spatial=1).

3The maximum increment in porosity in a single mechanical step is limited to 0.001.

 

 

Restoration data

Data File

 

 

* Restoration_data                      

! ---------------------------------

 Restoration_surface     "Restoration_surface"

 Operation_type          "Restore"

 Decompaction_type       "Continuous"  

 

 

1In addition to restoration operation and assignment of restoration surface Decompaction_type must be set to "Continuous" in order to perform decompaction during the current restoration step.

2Note that in this case decompaction is turned ON during the second restoration step as in the first one it is not required (the model started with porosity initialized according to the Normal Compaction Trend).

 

 

Results

The result files for the project are in directory: Rest_001\Exercises\Case3\Results  

 

Rest_001_Case3_Results

 

Porosity results at the end of each restoration step.