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.
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
PORO, POROSITY¶
PORO or POROSITY defines the aquifer porosity. Required.
PERM, PERMEABILITY¶
PERM or PERMEABILITY defines the aquifer permeability. Units must be specified. Required.
VISC, VISCOSITY¶
VISC or VISCOSITY defines the aquifer viscosity. Units must be specified. Required.
CMPR, COMPRESSIBILITY¶
CMPR or COMPRESSIBILITY defines the aquifer compressibility (rock + water): required.
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.
TINIT, TEMPERATURE¶
TINIT or TEMPERATURE defines the aquifer temperature. Temperature units must be specified.
Required for thermal runs.
GAS_IN_LIQUID_MOLE_FRACTION¶
Gas in liquid mole fraction in brine. Defaults to 0.0. Only used in GW mode.
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).
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 PFLOTRAN 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.