Fract_001 Fracture Data Import, Modification and Export

 

Introduction

 

The aim of this example is to demonstrate procedures of fracture data import and export. In the current example, we import fracture data that has been generated using FracMan software into ParaGeo environment. We then customise the fracture distribution through scaling and offsetting of fracture set within specified region of interest. Note that fractures that intersect with the defined fracture region boundaries are excluded, as illustrated below.

 

fract_001_fig1

Fig. 1 Exclusion of fractures intersecting with the defined fracture region boundaries of fractured sample

 

This modified fracture set is then exported in FracMan data file format so that the file can be re-used in subsequent simulation tests without the need to re-specify the fracture distribution.

 

 

Click to expand/collapseData File Description

The data file for the example is in: fract_001\Data\fract_001.dat.   The basic data includes:

1Include imports FracMan-formatted fracture data.

2Contact_property defines the mechanical and flow properties on the contact surfaces that are associated with the imported fracture data.

3Fracture_set assigns the fracture data to the contact property and volume geometry, customises the fracture distribution through scaling and offsetting of fracture set, defines the region size that encloses fracture distribution of interest and sets the flag to output modified fracture data file that can be re-used in subsequent simulation tests.

 

Note that only key data structures are described below.

 

Click to expand/collapseInclude

Include imports FracMan-formatted fracture data.

 

Data File

 

 

* Include

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

 Filename        "frac_sample.fab"

 

1FracMan-formatted fracture data is imported.

 

 

 

Click to expand/collapseContact_property

Contact_property defines the mechanical and flow properties on the contact surfaces that are associated with the imported fracture data.

 

Data File

 

 

* Contact_property

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

   Name                  "Frac_set1"

   Compression_model               1

   Compression_properties      IDM=1

    /"Normal Penalty"/           100

   Tangential_model                2

   Tangential_properties       IDM=2

    /"Tangential Penalty"/        10

    /"Friction coefficient"/     0.1  

   Flow_model_normal               1

   Flow_properties_normal      IDM=2

    /"Hydr.Cond.(Contact)"/    1.0E3

    /"Hydr.Cond.(Filter Cake"/ 1.0E3

   Flow_model_tangential           1

   Flow_properties_tangential  IDM=1

    /"Hydr. Cond. (Penalty)"/  1.0E3

   Contact_width                   5

 

 

1Contact property name ‘Frac_set1’ is defined. The name is to be linked with fracture set data structure.

2Mechanical and flow properties on the contact surfaces in normal and tangential directions are defined accordingly.

 

 

Click to expand/collapseFracture_set

Fracture_set assigns the fracture data to the contact property and volume geometry, customises the fracture distribution through scaling and offsetting of fracture set, defines the region size that encloses fracture distribution of interest and sets the flag to output modified fracture data file that can be re-used in subsequent simulation tests.

 

Data File

 

 

* Fracture_set                NUM=1

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

   Property_assignment   "Frac_set1"

   Volume                          1

   Active_flag                     1

   Split_flag                      1

   Element_size                    5

   Pre_intersect_out_flag          1

   Offset                      IDM=3

    /x-direction/             -40.0

    /y-direction/             -50.0

    /z-direction/              0.00

   Scale                       IDM=3

     1.25

     2.50

     2.00  

   Region_type           "Rectangle"

   Region_size                 IDM=6

     733   0     0      

     1000  210  50

   Fab_file_output   “frac_sample_2”

 

1The fracture set is assigned to the contact property named ‘Frac_set1’.

2The fracture set is assigned to the volume geometry number = 1.

3Active_flag = 1 sets this fracture set as active.

4Split_flag = 1 splits all contact surfaces under this fracture set.

5Pre_intersect_out_flag = 1 outputs geometry file without running analysis. Note that currently we are only interested in generating a fractured sample without running any analysis yet.

6The fracture distribution is offset in x and y directions.

7The fracture distribution is scaled in x, y and z directions.

8The region of interest is in rectangular form, defined using Region_type.

9Region size is defined using two points, which must be prescribed in the following order:

a.Lower coordinate point closest to the axis origin.

b.Upper coordinate point furthest from the axis origin.

10Fab_file_output defines the name of the modified fracture data file "frac_sample_2" to be generated.

 

 

Click to expand/collapseNodal_data

Nodal_data assigns coordinate points for each node defining the simulation domain.

 

Data File

 

 

* Nodal_data

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

   Node_number          IDM=8

     1 2 3 4 5 6 7 8

   Coordinates    IDM=3 JDM=8

     713  230   0

     1000        230   0

     1000        0     0

     713  0     0

     713  230  50

     1000        230  50

     1000        0    50

     713        0    50

 

1Node_number for each geometry vertices is defined.

2The coordinate points for each node are defined. It can be observed that the simulation domain is larger than the defined region of interest for fracture distribution. This is illustrated in the results section.

 

 

 

Click to expand/collapseResults

The result files for this example is available in directory: fract_001\Results. The fracture data is imported in such a way that any fractures that cross the defined fracture region boundaries (not simulation domain boundaries) are excluded. The final form of the model is also illustrated below.

 

fract_001_fig2

 

Fig. 2 Generation of fractured sample