Pflotran_coupling_data
Contents
Data Structure: Pflotran_coupling_data |
|
Description |
Reservoir -> Parageo Coupled dat structure |
Usage |
Pflotran_coupling_data NUM=ival where ival is the data structure number |
Description |
Overview Pflotran_coupling_data defines data required to couple ParaGeo with Pflotran or Pflotran-OGS. When coupling ParaGeo with a reservoir simulator like Pflotran, generally only the reservoir and the most permeable formations (including permeable faults) will be solved by the reservoir simulator and consequently only those formations will existin the flow grid whereas the ParaGeo model geometry will generally consider all the formations in the overburden plus any underburden and side burden. Hence the data from Pflotran model grid will be mapped to the equivalent formations (groups) in ParaGeo.
The data required is dependent on the coupling options, with the minimal data being the list of ParaGeo groups in the geomechanical model for which the flow will be solved by Pflotran or Plotran-OGS.
|
 | Volume_strain_coupling Flag denoting volume strain coupling algorithm |
Usage |
||||
|
||||
Description |
||||
Three options for coupling the volumetric strain for coupled geomechanical/porous flow analysis are available: • "None" - No loading due to volume strain in the porous flow field • "Fixed_stress" - The fixed stress algorithm includes the effect of rock compressibility into the storativity term of the porous flow field which is updated prior to the geomechanical field. The volume loading term in the porous flow field is then defined by the total stress rate divided by the drained bulk modulus as opposed to the volume strain rate. The total stress rate is evaluated based on the values at time t. The fixed stress algorithm can be used with both the incremental and iterative solution strategies. For the iterative algorithm the total stress rate is evaluated at time t for the first iteration and subsequently the value for the previous iteration is used. • "Undrained" - The undrained algorithm solves the porous flow field first using the standard equations with the volume strain loading evaluated from the volume change. The geomechanical field is then solved assuming a locally undrained response leading to an increase in pore pressure. This local increase in pore pressure is then removed in the next step and replaced by the local increase in the next step. Consequently there is always a difference between the pore pressure in the mechanical field and the porous flow field. If the coupling steps become too large this difference can become large so care must be taken to ensure that the time steps are sufficiently small.
|
| Volume_update_model Volume strain update algorithm |
Usage |
||||
|
||||
Description |
||||
• "Constant" - Constant stiffness (default if undrained algorithm). In this case a constant undrained stiffness is used when computing the pore pressure change in the mechanical field. This assumption is very stable and is suitable for low permeability systems. For more freely draining systems however it may result in a significant difference between the intra step pore pressure evaluation in the mechanical field and the actual pore pressure computed in the porous flow field. Consequently the "VariableGroup" method is generally recommended. • "VariableGroup" - Variable stiffness on Group Basis (Recommended). This method automatically computes an approximate undrained stiffness based on the average pore pressure change in the previous step in the porous flow field. This approximate undrained stiffness therefore accounts for the influence of drainage and results in intra step pore pressure prediction in the mechanical field that is much closer to the true pore pressure change computed in the porous flow field. To improve stability a factor of safety is always applied to the approximate undrained stiffness.
• "Fixed_stress" - Fixed stress (default if fixed stress algorithm).
|
| Permeability_update_flag Flag to indicate that permeability update should be performed |
Usage |
||||
|
||||
Description |
||||
Flag to indicate whether permeability update in Pflotran according to ParaGeo geomechanical calculations should be performed. Valid values are: • 0 - Do not update Pflotran permeability according to ParaGeo calculations. Default if coupling method 0 (One way coupling) • 1 - Update Pflotran permeability each coupling step according to ParaGeo calculations. Default if coupling method > 0 (Two way coupling)
|
| Pore_volume_update_flag Flag to indicate that pore volume update should be performed |
Usage |
||||
|
||||
Description |
||||
Flag to indicate whether permeability update in Pflotran according to ParaGeo geomechanical calculations should be performed. Valid values are: • 0 - Do not update Pflotran pore volume according to ParaGeo calculations. Default if coupling method 0 (One way coupling) • 1 - Update Pflotran pore volume each coupling step according to ParaGeo calculations. Default if coupling method > 0 (Two way coupling)
|
| Compressibility_update_flag Flag to indicate that compressibility update should be performed |
Usage |
||||
|
||||
Description |
||||
Flag to indicate whether compressibility update in Pflotran according to ParaGeo geomechanical calculations should be performed. Valid values are: •-1 - No update : Evaluate using D(porosity)/D(pore pressure) for plot file only. Default if coupling method > 0 (Two way coupling) •-2 - No update : Evaluate using elastic constants for plot file only •-3 - No update : Evaluate using D(porosity)/D(effective mean stress) for plot file only • 0 - No update. Default if coupling method 0 (One way coupling) • 1 - Update method 1: Evaluate using D(porosity)/D(pore pressure). Default if coupling method > 0 (Two way coupling) • 2 - Update method 2: Evaluate using elastic constants • 3 - Update method 3: Evaluate using D(porosity)/D(effective mean stress)
|
| Coupling_method Coupling algorithm |
Usage |
||||
|
||||
Description |
||||
Defines the coupling method to be used for the flow/geomechanical model. Valid options are: • 0 - Data passed from flow simulator to geomechanical simulator only • 1 - Date passed both ways at the end of hte step (Flow step performed first) (Default)
|
| Keep_transfer_files Keep transfer files |
Usage |
||||
|
||||
Description |
||||
Defines whether the transfer files are kept or deleted. Valid options are: • 0 - Do not keep transfer files (Default) • 1 - Keep transfer files
|
| Explicit_coupling_method Coupling algorithm for explicit (staggered) coupling Coupling_method = 1 |
Usage |
||||
|
||||
Description |
||||
Coupling method to be used for the flow/geomechanical model. Valid values are: •0 - Couple every time step (Default) |
| Units Units used in the reservoir simulator |
Usage |
|||||||||||||||
|
|||||||||||||||
Description |
|||||||||||||||
Units used in the reservoir simulator. By default the unit order is: •Location 1 - units for stress e.g. ("MPa", "KPa", "Pa", "psi", "bar") •Location 2 - units for length e.g. ("m", "mm", "km", "in", "ft") •Location 3 - units for time e.g. ("s", "hrs", "years", "Ma") •Location 4 - units for temperature e.g. ("Celsius", "Kelvin", "Fahrenheit", "Rankine") •Location 5 - units for conductivity e.g. ("W") •Location 6 - units for permeability e.g. ("m^2", "D", "mD", "microD", "nanoD", "ft^2") •Location 7 - units for density e.g. ("kg/m^3", "lb/ft^3", "lb/in^3", "lb/gal")
Notes •If units are specified they will be used to perform unit conversion during reservoir simulator->Parageo Data transfer •The default order of the units may be changed by specifying Units_list •If any unit value not specified no conversion will be performed for that quantity
|
|||||||||||||||
| Units_list List of unit types corresponding to Units |
Usage |
|||||||||||||||
|
|||||||||||||||
Description |
|||||||||||||||
List of unit types corresponding to the values defined in Units. Valid names include: • "stress" - "stress" • "length" - "length" • "time" - "time" • "temperature" - "temperature" • "conductivity" - "conductivity" • "permeability" - "permeability" • "density" - "density"
|
|||||||||||||||
| Output_pflotran_mesh Flag to generate a Pflotran mesh file |
Usage |
||||
|
||||
Description |
||||
Flag to generate a Pflotran mesh file for the selected groups. Execution is terminated after file generation. Valid values are: • 0 - Do not generate .ugi file (default) • 1 - Generate .ugi file
|
| Output_pflotran_mesh_file_name Flag to generate a Pflotran mesh file for the reservoir |
Usage |
||||
|
||||
Description |
||||
Defines the name for the pflotran .ugi mesh file as well as the root name for the geometry set files to be output. Note for each geometry set a .ss or a .txt file will be generated (depending whether the geometry set data referes to surfaces or volumes respectively). So for every geometry set a file named PflotranMeshFileName_GeometrySetName.ss or .txt will be output.
|
| Default_porosity Default matrix porosity for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default matrix porosity for elements corresponding to inactive reservoir cells. If a default value is not specified then it will be obtained based on the input value for the element.
|
| Default_pore_pressure Default pore pressure for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default pore pressure for elements corresponding to inactive reservoir cells (default =0.0).
|
| Default_mixture_density Default mixture density for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default mixture density for elements corresponding to inactive reservoir cells. The default is the fluid density assigned to the element group.
|
| Default_gas_saturation Default gas saturation for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default gas saturation for elements corresponding to inactive reservoir cells. The default value is zero.
|
| Default_gas_density Default gas density for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default gas density for elements corresponding to inactive reservoir cells. The default value is zero.
|
| Default_oil_saturation Default oil saturation for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default oil saturation for elements corresponding to inactive reservoir cells. The default value is zero.
|
| Default_oil_density Default oil density for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default oil density for elements corresponding to inactive reservoir cells. The default value is zero.
|
| Default_water_saturation Default water saturation for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default water saturation for elements corresponding to inactive reservoir cells. The default value is 1.0.
|
| Default_water_density Default water density for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default water density for elements corresponding to inactive reservoir cells. The default is the fluid density assigned to the element group.
|
| Default_temperature Default temperature for elements corresponding to inactive reservoir cells |
Usage |
||||
|
||||
Description |
||||
Default temperature for elements corresponding to inactive reservoir cells. The default value is 0.0.
|
| Inactive_element_factor Inactive element factor below which elements are considered inactive for reservoir flow |
Usage |
||||
|
||||
Description |
||||
Inactive element factor below which elements are considered inactive for reservoir flow Default 0.1.
|
| Max_compressibility_change Maximum compressibility change factor within a time step |
Usage |
||||
|
||||
Description |
||||
Maximum compressibility change factor within a time step. The default value is 0.1, so that the allowable change is 0.1 * the previous compressibility value.
|
| Max_matrix_compressibility Maximum compressibility in the matrix |
Usage |
||||
|
||||
Description |
||||
Maximum compressibility in the matrix.
|
| Min_matrix_porosity Minimum porosity in the matrix |
Usage |
||||
|
||||
Description |
||||
Minimum porosity in the matrix (Default: 0.001).
|
| Max_matrix_porosity Maximum porosity in the matrix |
Usage |
||||
|
||||
Description |
||||
Maximum porosity in the matrix (default: 0.98).
|
| Init_matrix_stiff_flag Initialise matrix stiffness flag |
Usage |
||||
|
||||
Description |
||||
Defines how the matrix stiffness should be initialised. Valid values are: • 0 - Standard ParaGeo initialisation • 1 - Initialise matrix stifness using reservoir compressibility (default)
Initialisation of matrix stiffness using reservoir compressibility is recommended as: •It ensures compatability between the initial reservoir and geomechanical compressibility •generally the reservoir model has a finer discretisation, so it is better to initialised the upscaled geomechanical compressibility rather than the downscaled the geomechanical compressibility to initialise the reservoir compressibility
|
| Integration_constant Integration constant for pore pressure and compressibility |
Usage |
||||
|
||||
Description |
||||
The default integration for evaluation of data to be transfered to and from the Reservoir Simulator is a general Alpha method where an integration constant ( αp) for pore pressure and compressibility where 0.0 < = αp < = 1.0. The default value for αp = 0.5 corresponding to values at the mid-point of the coupling time step.
Notes •if Interpolation_level_geo > 0 then the αp integration method will not be used for ParaGeo->Reservoir transfer computations •if Interpolation_level_res > 0 then the αp integration method will not be used for Reservoir->ParaGeo transfer computations
|
| Interpolation_level_geo Interpolation level for ParaGeo->Reservoir data |
Usage |
||||
|
||||
Description |
||||
A multi-level weighted moving average may be used to interpolate data computed in ParaGeo to be passed to the Reservoir Simulator; i.e. pore volume multiplier and compressibility multipliers. The scheme is activated by specifying the number of points for the moving average algorithm (e.g. 5-points).
Notes •if Interpolation_level_geo = 0 then the αp integration method will be used •if Interpolation_level_geo > 0 and Interpolation_level_res is not defined, then Interpolation_level_res = Interpolation_level_geo
|
| Interpolation_level_res Interpolation level for ParaGeo->Reservoir data |
Usage |
||||
|
||||
Description |
||||
A multi-level weighted moving average may be used to interpolate data computed in the Reservoir Simulator to be passed to Parageo; i.e. Pore pressure. The scheme is activated by specifying the number of points for the moving average algorithm (e.g. 5-points).
Notes •if Interpolation_level_res = 0 then the αp integration method will be used •if Interpolation_level_res > 0 and Interpolation_level_geo is not defined, then Interpolation_level_geo = Interpolation_level_res
|
| Bulk_damping_constant Bulk damping constant |
Usage |
||||
|
||||
Description |
||||
Bulk damping constant (Default 0.5).
|
| Map_type Map type |
Usage |
||||
|
||||
Description |
||||
Defines the type of contribution from the geomechanical "background" mesh to the Pflotran mesh for coupling purposes. Valid types are: • "Single" - Single background element contribution where each Pflotran element receives data from a single ParaGeo element. • "Multiple" - Multiple background elements contribution where each Pflotran element recieves data from multiple ParaGeo elements.
|
| Map_division_length Length of a division in the longest direction |
Usage |
||||
|
||||
Description |
||||
Defines the longest length of a division (geomechanical elements).
|
| Map_max_number_divisions Maximum permitted number of divisions in the longest direction |
Usage |
||||
|
||||
Description |
||||
Defines the maximum number of geomechanical elements conributing to coupling to a single Pflotran element.
|
| Groups List of ParaGeo groups forming the reservoir(s). |
Usage |
|||||||||||||||
|
|||||||||||||||
Description |
|||||||||||||||
List of ParaGeo groups forming the reservoir(s).
|
|||||||||||||||
| Mapping_type Mapping type |
Usage |
||||
|
||||
Description |
||||
Type of mapping to be used when transferring data between the reservoir and geomechanical meshes. Valid values are: • 1 - Simple closest point mapping • 2 - Mapping via average of background elements
|
| Porosity_tolerance Tolerance for warning messages for initial reservoir/geomechanical porosity |
Usage |
||||
|
||||
Description |
||||
The porosity is initialised on both the geomechanical and reservoir meshes. If the values differ by more than Porosity_tolerance a warning message is output.
|
| Cell_history Output history at specified cells |
Usage |
|||||||||||||||
|
|||||||||||||||
Description |
|||||||||||||||
Output history data at specified reservoir cells
|
|||||||||||||||
| Output_level Output level for checking coupling communication |
Usage |
||||
|
||||
Description |
||||
Output level for checking coupling communication.
|