AQUIFER_DATA

Defines an analytical aquifer, which can be modelled by either Carter-Tracy [CT+60]. or Fetkovich [Fet71]. The Carter-Tracy is the default model, which can be used to either describe a radial or linear aquifer.

AQUIFER_DATA must be followed by a name for the aquifer. For example:

AQUIFER_DATA A1
  BACKFLOW
  DEPTH     2550.0 m
  THICKNESS 100 m
  RADIUS    507.8 m
  PERM      500  mD
  COMPRESSIBILITY 2.0E-9 1/Pa
  POROSITY  0.1
  VISCOSITY 1 cP
  CONN_D 1 1 1 9 1 1 X- 3.0
  CONN_D 1 9 1 1 1 1 Y- 3.0
END

It is possible to connect the same aquifer to more grid blocks; connections can be added by multiple lines within the definition of one aquifer (see the multiple CONN_D lines above).

The options supported by AQUIFER_DATA are:

BACKFLOW

Specifies that fluids are allowed to migrate from the reservoir to the aquifer.

This option should be used with caution, as it can result in unwanted fluid re-circulations between grid blocks connected to the same aquifer. As a general rule an aquifer should be far away from the main injection/production regions. See example above for a reference on how to use it.

DEPTH

Specify aquifer depth. Units are required. See example above for a reference on how to use it.

ZAQUIFER

Specify aquifer elevation. For example if the aquifer depth is 2500 m, ZAQUIFER will be -2500 m. Units are required.

THETA_FRACTION, THETA

Specify the aquifer angle (for a radial aquifer). Defaulted to a THETA_FRACTION of 1.0. THETA allows the same data to be added as an angle in degrees - .e.g. THETA 145.

So THETA_FRACTION = THETA/360.0.

See example below:

AQUIFER_DATA north
  BACKFLOW
  THETA 45
  DEPTH     1225.0 m
  THICKNESS  50 m
  RADIUS    3000.0 m
  PERM      300  mD
  TEMPERATURE 53.0 C
  COMPRESSIBILITY 2.0E-9 1/Pa
  POROSITY  0.3
  VISCOSITY 1 cP
  CONN_D 1  20 20 20 4 13 Y+
END

THICKNESS

Aquifer thickness. Required. Units must be specified. See example above for a reference on how to use it.

WIDTH

Aquifer width, required for linear aquifer. Units must be specified. Example:

AQUIFER_DATA A1
  BACKFLOW
  DEPTH     2600.0 m
  WIDTH     1500.0 m
  THICKNESS 1500.0 m
  PERM      10  mD
  TEMPERATURE 75 C
  COMPRESSIBILITY 2.0E-9 1/Pa
  POROSITY  0.2
  VISCOSITY 1 cP
  CONN_D 1 30 1 30 10 10 Z+
END

RADIUS

Aquifer inner radius. Required for radial aquifer. Units must be specified. See example above for a reference on how to use it.

PORO, POROSITY

PORO or POROSITY defines the aquifer porosity. Required. See example above for a reference on how to use it.

PERM, PERMEABILITY

PERM or PERMEABILITY defines the aquifer permeability. Units must be specified. Required. See example above for a reference on how to use it.

VISC, VISCOSITY

VISC or VISCOSITY defines the aquifer viscosity. Units must be specified. Required. See example above for a reference on how to use it.

CMPR, COMPRESSIBILITY

CMPR or COMPRESSIBILITY defines the aquifer compressibility (rock + water): required. See example above for a reference on how to use it.

PINIT, PRESSURE

PINIT or PRESSURE defines the aquifer pressure. Pressure units must be specified. Not required, if not entered the aquifer pressure will be set in equilibrium with reservoir.

See example below:

AQUIFER_DATA north
  BACKFLOW
  DEPTH     1225.0 m
  THICKNESS  50 m
  RADIUS    3000.0 m
  PERM      300  mD
  PINIT     125 Bar
  TEMPERATURE 53.0 C
  COMPRESSIBILITY 2.0E-9 1/Pa
  POROSITY  0.3
  VISCOSITY 1 cP
  CONN_D 1  20 20 20 4 13 Y+
END

TINIT, TEMPERATURE

TINIT or TEMPERATURE defines the aquifer temperature. Temperature units must be specified.

Required for thermal runs.

For an example including TINIT, see above.

GAS_IN_LIQUID_MOLE_FRACTION

Gas in liquid mole fraction in brine. Defaults to 0.0. Only used in GW mode. Example:

AQUIFER_DATA A1
  BACK
  FET
  PV 10000000 m^3
  PI 1000     m^3/d/bar
  DEPTH     2560.32 m
  COMPRESSIBILITY 1.0E-9 1/Pa
  GAS_IN_LIQUID_MOLE_FRACTION 0.5D-3
  CONN_D 1 1 1 1 1 1 X-
  CONN_D 1 1 1 1 2 2 X- 3.0
END

IFT

Influence function table. Not required. If omitted, defaults to infinite aquifer.

Example:

IFT
   0.01 0.112
   0.05 0.229
   0.10 0.315
   0.15 0.376
   0.20 0.424
   0.25 0.469
   0.30 0.503
   0.40 0.564
   0.50 0.616
   0.60 0.659
   0.70 0.702
   0.80 0.735
   0.90 0.772
   1.00 0.802
   1.50 0.927
   2.0  1.020
   2.5  1.101
   3.0  1.169
   4.0  1.275
   5.0  1.362
   6.0  1.436
   7.0  1.500
   8.0  1.556
   9.0  1.604
   10.0 1.651
   15.0 1.829
   20.0 1.960
   25.0 2.067
   30.0 2.147
   40.0 2.282
   50.0 2.388
   60.0 2.476
   70.0 2.550
   80.0 2.615
   90.0 2.672
  100.0 2.723
  150.0 2.921
  200.0 3.064
  250.0 3.173
  300.0 3.263
  400.0 3.406
  500.0 3.516
  600.0 3.608
  700.0 3.684
  800.0 3.750
  900.0 3.809
 1000.0 3.860
END IFT

CONN_D

Specifies blocks of connections to attach aquifer to reservoir cell faces. Follows the ECLIPSE grdecl convention (K index is counted downwards from the top layer).

See example above.

An example is:

CONN_D 1 9 9 9 1 1 Y+ 3.0

Note that the connection box argument order is:

CONN_D IL IU JL JU KL KU CMF

Where:

  • IL and IU are a range of cell indices in the I-direction

  • JL and JU are a range of cell indices in the J-direction

  • KL and KU are a range of cell indices in the K-direction

  • CMF: connection multiplier factor (optional)

Connections will be made to cells with I-indices such that \(I \geq IL\) and \(I \leq IU\), etc.

The cell faces to attach the aquifer are specified by one of the following options:

  • X+ or I+, faces connecting cells with I-indices to cells with (I+1)-indices

  • Y+ or J+, faces connecting cells with J-indices to cells with (J+1)-indices

  • Z+ or K+, faces connecting cells with K-indices to cells with (K+1)-indices

The pairs (X- or I-), (Y- or I-) and (Z- or K-) follow the same logic, and are used to connect to cells with (I-1)-indices, (J-1)-indices and (K-1)-indices.

A number of CONN_D sub-keywords may be entered to build up the full connection. If the same face of the same cell is included more than once, only one connection will be generated.

CONN_Z

Warning: keyword to be used only by proficient Cirrus users. Unless there is some specific reason, consider using CONN_D instead.

Specifies blocks of connections to attach aquifer to reservoir cell faces.

CONN_Z use the convention that the K index is counted upwards from the bottom layer. For example:

CONN_Z 1 9 9 9 1 1 Y+ 3.0

Note that the connection box argument order is:

CONN_Z IL IU JL JU KL KU CMF

Where:

  • IL and IU are a range of cell indices in the I-direction

  • JL and JU are a range of cell indices in the J-direction

  • KL and KU are a range of cell indices in the K-direction

  • CMF: connection multiplier factor (optional)

Connections will be made to cells with I-indices such that \(I \geq IL\) and \(I \leq IU\), etc.

The cell faces to attach the aquifer are specified by one of the following options:

  • X+ or I+, faces connecting cells with I-indices to cells with (I+1)-indices (GRDECL grid format).

  • Y+ or J+, faces connecting cells with J-indices to cells with (J+1)-indices (GRDECL grid format).

  • Z+ or K+, faces connecting cells with K-indices to cells with (K+1)-indices (K index counted upwards from the bottom layer).

The pairs (X- or I-), (Y- or I-) and (Z- or K-) follow the same logic, and are used to connect to cells with (I-1)-indices, (J-1)-indices and (K-1)-indices.

When using CONN_Z, the top faces of a reservoir with 100 layers are defined with Z+. See the following example:

CONN_Z  1 50 1 50  100 100  Z+

FET

Selects a Fetkovich analytical aquifer [Fet71], instead of the Carter-Tracy, which is the default model otherwise. A FET aquifer requires the user to specify the aquifer pore volume (PV), and the aquifer productivity index (PI), both referring to surface volumes. See example below:

AQUIFER_DATA AQ1
   BACK
   FET
   PV 10000000 m^3
   PI 1000 m^3/d/bar
   DEPTH 2500 m
   COMPRESSIBILITY 1.0E-4 1/Bar
   CONN_D 1 20 1 10 1 20 X-
END

Note that the aquifer porosity, permeability, viscosity, internal radius/thickness and angle (theta) are not required.

PV

Specifies the aquifer pore volume at surface conditions, required only by the Fetkovich aquifer (see FET for an example).

PI

Specifies the aquifer productivity index in terms of surface volumes. This is required only by the Fetkovich aquifer (see FET for an example).

AQCON_AREA/AQCON_AREA_PERM

These are options for controlling the manner in which the total aquifer-resevoir flow is divided between all the cells connected to the aquifer.

If AQCON_AREA is used the flow is divided on the basis of the area of the cell face connected to the aquifer If AQCON_AREA_PERM is used the flow is divided on the basis of the product of the area of the cell face and the permeability of the the cell in the direction of the face.

The default is AQCON_AREA.

These keywords have no arguments.

Note that these two keywords can be used in both the AQUIFER_DATA and AQNUM_DATA blocks.

See example below:

AQUIFER_DATA north
  BACKFLOW
  AQCON_AREA_PERM
  DEPTH     1225.0 m
  THICKNESS  50 m
  RADIUS    3000.0 m
  PERM      300  mD
  TEMPERATURE 53.0 C
  COMPRESSIBILITY 2.0E-9 1/Pa
  POROSITY  0.3
  VISCOSITY 1 cP
  CONN_D 1  20 20 20 4 13 Y+
END

ALLOW_ACTIVE_NEIGHBOUR

Alias: ALLOW_ACTIVE_NEIGHBOR.

The default rule for creating aquifer connections matches Eclipse, but is different from Intersect ©, which allows connections to cell faces which have an active neighbour on that face.

When this keyword is used, a connection is made to the specified face irrespective of whether it has an active neighbour on that face. This matches the Intersect © methodolgy.

(Intersect © of the Schlumberger Corporation).

Examples of the use of this keyword may be found in the repository in the folder:

cirrus_1.9/regression_tests/towg/bo/

aquifer_linear_ac_allow.in:

AQUIFER_DATA A1
  DEPTH     2550.0 m
  THICKNESS 100 m
  WIDTH     100 m
  PERM      500  mD
  COMPRESSIBILITY 2.0E-9 1/Pa
  POROSITY  0.2
  VISCOSITY 1 cP
  CONN_D 19 19 1 1 1 1 X+
  ALLOW_ACTIVE_NEIGHBOUR
END

And in acnum_ac__allow.in:

AQNUM_DATA A1
  RPV 200000000 m^3
  RPI 2.13175 m^3/d/bar
  CONN_D 9 9 1 1 1 1 X+
  VISC 2 cp
  REP_CELL_D 12 1 1
  ALLOW_ACTIVE_NEIGHBOUR
END