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GEOTHERMAL_FRACTURE_MODEL¶

Defines paramters and controls the creation of individual fractures or statistical fracture families for thermo-hydro-mechanical-chemical simulations of flow through an equivalent continuous porous media representation of discrete fracture networks. Note: only TH Mode is fully tested as a compatible flow mode, although this process model may also work with GENERAL Mode (use at your own risk with General Mode).

Required Cards:¶

GEOTHERMAL_FRACTURE_MODEL

Opens the geothermal fracture model block. Must be closed with END or a forward slash (/).

THERMAL_EXPANSION_COEFFICIENT <float>

Specifies the thermal expansion coefficient [C^-1] for the matrix rock material. A value typical for granite is 40.6d-6 C^-1, however, no default value is provided so this parameter must be specified. This parameter contributes to the calculation of the hydraulic aperture evolution and the resulting changes in fracture permeability.

FRACTURE

Opens a FRACTURE block, which defines parameters and controls for individual fractures in the domain. Must be closed with END or a forward slash (/).

ID <integer>: Specifies an identification number for the fracture.
HYDRAULIC_APERTURE <float>: Specifies the hydraulic aperture [m] of a fracture. This value is used to calculate the initial permeability, unperturbed by geochemistry or thermal expansion/contraction of the matrix rock.
CENTER <float> <float> <float>: Specifies the x, y, and z coordinates [m] in space for where the center of the fracture plane is located within the domain.
NORMAL_VECTOR <float> <float> <float>: Specifies the x, y, and z components [m] of the vector that is orthogonal, or normal, to the fracture plane. This vector does not need to be a unit vector.
RADIUS_X <float>: Specifies the maximum extent [m] of the fracture in the x-axis of the domain from the center of the fracture plane. While this is not a true radius, in the traditional definition of a radius, one can think of it in the sense of a radius for a cuboid shape.
RADIUS_Y <float>: Specifies the maximum extent [m] of the fracture in the y-axis of the domain from the center of the fracture plane. While this is not a true radius, in the traditional definition of a radius, one can think of it in the sense of a radius for a cuboid shape.
RADIUS_Z <float>: Specifies the maximum extent [m] of the fracture in the z-axis of the domain from the center of the fracture plane. While this is not a true radius, in the traditional definition of a radius, one can think of it in the sense of a radius for a cuboid shape.
MAX_DISTANCE <float>: Specifies the maximum distance [m] between the grid cell center and the location of the defined fracture plane for which the algorithm will search when tagging which grid cells are occupied by a fracture. The default value is 5.0d0 [m]. The value should be set to a number that is roughly on the order of the grid cell size. If you find that fractures at an angle are disconnected, then try increasing the value for MAX_DISTANCE. Do not increase it much larger than is required to get continuous fractures or the fractured zone will become unrealistically large (grid cells that are not occupied by the fracture plane will be tagged as containing a fracture because their neighbor was occupied by the fracture plane).

FRACTURE_FAMILY

Opens a FRACTURE_FAMILY block, which defines parameters and controls for fracture families that are defined by statistical distributions. Must be closed with END or a forward slash (/). Currently, the only type of distribution available is a normal Gaussian or a truncated normal Guassian distribution which is defined by a mean value and a standard deviation. If truncated, a value for the minimum or maximum value may also be provided.

ID <integer>

Specifies an identification number for the fracture family.

NUMBER_OF_FRACTURES <integer>

Specifies the total number of individual fractures that are created for the fracture family.

HYDRAULIC_APERTURE

Opens a HYDRAULIC_APERTURE sub-block, which defines the statistical parameters for the fracture family’s hydraulic aperture. Must be closed with END or a forward slash (/).

HYDRAULIC_APERTURE_VALUE <float>: Specifies the mean hydraulic aperture value [m] for the normal Gaussian distribution that is sampled from when generating the fracture family.
HYDRAULIC_APERTURE_STDEV <float>: Specifies the standard deviation of the hydraulic aperture value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s hydraulic aperture in the fracture family.
HYDRAULIC_APERTURE_SEED <integer>: Specifies the seed which is used to sample randomly from the normal Gaussian distribution when generating the hydraulic aperture for an individual fracture within a fracture family. If you do not like the discrete fracture network that was generated for a certain seed value, you can simply change the seed value in the input deck and generate a new fracture network. Specifying the same seed will ensure that the same fracture network is generated each time the input deck is run.
HYDRAULIC_APERTURE_MAX <float>: Specifies the maximum value for the hydraulic aperture [m] in a normal Gaussian distribution, therefore making the distribution truncated.

CENTER

Opens a CENTER sub-block, which defines the statistical parameters for the fracture family’s center in space. Must be closed with END or a forward slash (/).

COORDINATE <float> <float> <float>: Specifies the x, y, and z coordinates [m] in space for where the mean center of the fracture family’s fracture plane is located within the domain.
XCOORD_STDEV <float>: Specifies the standard deviation of the x coordinate value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s x-coordinate in the fracture family.
YCOORD_STDEV <float>: Specifies the standard deviation of the y coordinate value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s y-coordinate in the fracture family.
ZCOORD_STDEV <float>: Specifies the standard deviation of the z coordinate value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s z-coordinate in the fracture family.
CENTER_SEED <integer>: Specifies the seed which is used to sample randomly from the normal Gaussian distribution when generating the center x, y, or z coordinate for an individual fracture within a fracture family. If you do not like the discrete fracture network that was generated for a certain seed value, you can simply change the seed value in the input deck and generate a new fracture network. Specifying the same seed will ensure that the same fracture network is generated each time the input deck is run.

NORMAL_VECTOR

Opens a NORMAL_VECTOR sub-block, which defines the statistical parameters for the fracture family’s orientation in space. Must be closed with END or a forward slash (/).

VECTOR_COORDINATES <float> <float> <float>: Specifies the x, y, and z vector coordinates [m] in space for the vector that is orthogonal (or normal) to the fracture family’s mean fracture plane.
XCOORD_STDEV <float>: Specifies the standard deviation of the x coordinate value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s x-component of the normal vector in the fracture family.
YCOORD_STDEV <float>: Specifies the standard deviation of the y coordinate value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s y-component of the normal vector in the fracture family.
ZCOORD_STDEV <float>: Specifies the standard deviation of the z coordinate value [m] for the normal Gaussian distribution that is sampled from when generating an individual fracture’s z-component of the normal vector in the fracture family.
NORMAL_SEED <integer>: Specifies the seed which is used to sample randomly from the normal Gaussian distribution when generating the normal vector x, y, or z components for an individual fracture within a fracture family. If you do not like the discrete fracture network that was generated for a certain seed value, you can simply change the seed value in the input deck and generate a new fracture network. Specifying the same seed will ensure that the same fracture network is generated each time the input deck is run.

RADIUS

Opens a RADIUS sub-block, which defines the statistical parameters for the fracture family’s extent in space. Must be closed with END or a forward slash (/).

RADIUS_XYZ <float> <float> <float>: Specifies the mean x, y, and z lengths [m] in space for the distance from the mean fracture family center to the end of the fracture plane, in the x, y, and z directions in reference to the coordinate system of the domain.
RAD_X_STDEV <float>: Specifies the standard deviation of the mean length in the x direction [m] from the mean fracture family center to the end of the fracture plane in reference to the coordinate system of the domain in the normal Gaussian distribution that is sampled from.
RAD_Y_STDEV <float>: Specifies the standard deviation of the mean length in the y direction [m] from the mean fracture family center to the end of the fracture plane in reference to the coordinate system of the domain in the normal Gaussian distribution that is sampled from.
RAD_Z_STDEV <float>: Specifies the standard deviation of the mean length in the z direction [m] from the mean fracture family center to the end of the fracture plane in reference to the coordinate system of the domain in the normal Gaussian distribution that is sampled from.
RADIUS_SEED <integer>: Specifies the seed which is used to sample randomly from the normal Gaussian distribution when generating the length in the x, y, or z radius directions for an individual fracture within a fracture family. If you do not like the discrete fracture network that was generated for a certain seed value, you can simply change the seed value in the input deck and generate a new fracture network. Specifying the same seed will ensure that the same fracture network is generated each time the input deck is run.

MAX_DISTANCE <float>

Specifies the maximum distance [m] between the grid cell center and the location of the defined fracture plane for which the algorithm will search when tagging which grid cells are occupied by a fracture. The default value is 5.0d0 [m]. The value should be set to a number that is roughly on the order of the grid cell size. If you find that fractures at an angle are disconnected, then try increasing the value for MAX_DISTANCE. Do not increase it much larger than is required to get continuous fractures or the fractured zone will become unrealistically large (grid cells that are not occupied by the fracture plane will be tagged as containing a fracture because their neighbor was occupied by the fracture plane).

Examples¶

GEOTHERMAL_FRACTURE_MODEL

  THERMAL_EXPANSION_COEFFICIENT 40.d-6 # [1/C]

  FRACTURE_FAMILY
    ID 1
    NUMBER_OF_FRACTURES 10  # [-]
    HYDRAULIC_APERTURE
      HYDRAULIC_APERTURE_VALUE 5.d-4  # [m]
      HYDRAULIC_APERTURE_STDEV 3.d-4 # [m]
      HYDRAULIC_APERTURE_SEED 105  # [-] must be an integer
      HYDRAULIC_APERTURE_MAX 1.d-2  # [m]
    /
    CENTER
      COORDINATE 25.d0 0.5d0 15.d0  # [m]
      XCOORD_STDEV 15.5d0  # [m]
      YCOORD_STDEV 1.5d0  # [m]
      ZCOORD_STDEV 1.5d0  # [m]
      CENTER_SEED 19  # [-] must be an integer
    /
    NORMAL_VECTOR
      VECTOR_COORDINATES -1.0d0 0.d0 -1.d0 # [m]
      XCOORD_STDEV 0.5d0  # [m]
      YCOORD_STDEV 0d0  # [m]
      ZCOORD_STDEV 0.5d0  # [m]
      NORMAL_SEED 29  # [-] must be an integer
    /
    RADIUS
      RADIUS_XYZ 50.d0 50.d0 100.d0 # [m]
      RAD_X_STDEV 50.0d0  # [m]
      RAD_Y_STDEV 10.0d0  # [m]
      RAD_Z_STDEV 5.0d0  # [m]
      RADIUS_SEED 31  # [-] must be an integer
    /
    MAX_DISTANCE 0.25 # [m]
  /

  FRACTURE_FAMILY
    ID 2
    NUMBER_OF_FRACTURES 6  # [-]
    HYDRAULIC_APERTURE
      HYDRAULIC_APERTURE_VALUE 5.d-3  # [m]
      HYDRAULIC_APERTURE_STDEV 2.d-3 # [m]
      HYDRAULIC_APERTURE_SEED 10  # [-] must be an integer
      HYDRAULIC_APERTURE_MAX 1.d-2  # [m]
    /
    CENTER
      COORDINATE 25.d0 0.5d0 15.d0  # [m]
      XCOORD_STDEV 8.5d0  # [m]
      YCOORD_STDEV 1.5d0  # [m]
      ZCOORD_STDEV 1.5d0  # [m]
      CENTER_SEED 66  # [-] must be an integer
    /
    NORMAL_VECTOR
      VECTOR_COORDINATES -1.0d0 0.d0 1.d0 # [m]
      XCOORD_STDEV 0.1d0  # [m]
      YCOORD_STDEV 0.0d0  # [m]
      ZCOORD_STDEV 0.3d0  # [m]
      NORMAL_SEED 7  # [-] must be an integer
    /
    RADIUS
      RADIUS_XYZ 50.d0 50.d0 5.d0 # [m]
      RAD_X_STDEV 10.0d0  # [m]
      RAD_Y_STDEV 10.0d0  # [m]
      RAD_Z_STDEV 3.0d0  # [m]
      RADIUS_SEED 5  # [-] must be an integer
    /
    MAX_DISTANCE 0.31 # [m]
  /

  FRACTURE
    ID 1
    HYDRAULIC_APERTURE 1.d-3 # [m]
    CENTER 25.d0 0.5d0 10.0d0 # [m]
    NORMAL_VECTOR -0.15d0 0.d0 1.d0 # [m]
    RADIUS_X 20.d0 # [m]
    RADIUS_Y 100.d0 # [m]
    RADIUS_Z 100.d0 # [m]
  /

  FRACTURE
    ID 3
    HYDRAULIC_APERTURE 1.d-3 # [m]
    CENTER 25.d0 0.5d0 12.5d0 # [m]
    NORMAL_VECTOR -0.15d0 0.d0 1.d0 # [m]
    RADIUS_X 20.d0 # [m]
    RADIUS_Y 100.d0 # [m]
    RADIUS_Z 100.d0 # [m]
    MAX_DISTANCE 0.1 # [m]
  /
  FRACTURE
    ID 2
    HYDRAULIC_APERTURE 6.d-4 # [m]
    CENTER 25.5d0 0.5d0 11.0d0 # [m]
    NORMAL_VECTOR 0.15d0 0.d0 1.d0 # [m]
    RADIUS_X 20.d0 # [m]
    RADIUS_Y 100.d0 # [m]
    RADIUS_Z 100.d0 # [m]
  /

/

GEOTHERMAL_FRACTURE_MODEL¶

Required Cards:¶

Examples¶

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