Well_definition
Contents
Data Structure: Well_definition |
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Description |
Data structure to define a well |
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Well_definition NUM=ival where ival is the data structure number |
Description |
Overview This data structure allows definition of injection and production wells for porous flow analysis and injection, production and U-shaped closed loop wells for thermal flow analysis. The well path points assigned to the well is defined by Well_path. For injection and production wells, the well path should be defined starting from the model surface and terminate within the reservoir or aquifer. For U-shaped closed loop wells, the outlet point can be at the same depth level as the injection point. Individual nodes of the well may be defined as "open" (leak off) or "shut"/"casing" (no leak-off).
Fluid flow within the injector/producer well may be defined via: •Injection Rate (e.g. m^3/day) •Production Rate (e.g. m^3/day) •Surface pore pressure
Temperature within the injector well may be defined via: •Well_temperature or Well_temperature_distribution •Surface temperature
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 | Active_flag Active flag |
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Flag to define whether the Well is active. Generally not required as if the data structure is defined it is set active by default. Valid values are: •-1 - Deactivate and remove if defined • 1 - Defined and active
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| Name Name of the well |
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Name of the well.
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| Singlephase_fluid_name Single phase fluid assignment |
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Assigns a single-phase fluid to the well. The single-phase fluid properties are defined on the Fluid_properties data structure.
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| Singlephase_fluid Defines the fluid in well |
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Assigns a single-phase fluid data number to the well. The single-phase fluid properties are defined on the Fluid_properties data structure.
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| Completion Defines the well completion set ID number |
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Assigns the associated well completion set ID number for all elements defining the well path. This keyword is used when a single Well_completion data is associated with the current well. If more than one Well_completion data is associated to the current well then Completion_distribution keyword must be used instead.
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| Completion_distribution List of well completion set ID numbers |
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Assigns the well completion set ID number for each element defining the well path. This keyword is used when more than one Well_completion data is associated to the current well. If a single Well_completion data is associated with the current well then Completion keyword must be used instead.
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| Surface_pressure Surface well pressure if prescribed |
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If Surface_pressure is defined then the surface well pressure is defined for the well.
Notes •Well_type must be defined in conjunction with use of Surface_pressure well loading.
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| Production_rate Production rate |
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The Production_rate is the volume flow rate (positive value) for production wells. The total production rate is evenly distributed among the "open" well points.
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| Injection_rate Production rate and Injection rate |
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The Injection_rate is the volume flow rate (positive value) for injection wells. The total injection rate is evenly distributed among the "open" well points.
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| Time_curve Time curve name or number |
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Time curve name or number associated with well loading, i.e. Surface_pressure, Production_rate and Injection_rate.
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| Well_path Well coordinates |
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Coordinates of points defining the path for the well (top to bottom). •1 - X, Y, Z in 3-D or X, Y in 2-D
Notes •The format for the path coordinates may be defined using Path_format.
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| Path_format Format of data defining well path |
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Flag to define the format for data defining the well path. Valid settings are:
3D models • 1 - X Y Z in 3D (Default if path coordinates specified) • 2 - X Y Depth (+ve) in 3D • 3 - X Y Depth (-ve) in 3D
2D models • 1 - X Y in 2D (Default if path coordinates specified) • 2 - X Depth (+ve) in 2D • 3 - X Depth (-ve) in 2D
Notes •X, Y, Depth format data require the stratigraphy for the problem to be defined.
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| Status Well status (constant) |
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Defines the well status for every segment of well (along all the well). • "open" - Open with leak off • "shut" - Shut with no leak off • "casing" - Cased well with no leak off
Notes •If a variable status along the well is required use Status_distribution.
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| Status_distribution Status distribution |
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Defines the status at each point defining the well: •"open" - leak off •"shut" - no leak off •"casing" - no leak off
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| Radius Well radius (constant) |
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Defines the well radius (constant for every segment of well). In thermal applications, if Heat_model equals "Constant", the Radius keyword means the outermost wellbore radius. If the Heat_model equals "Cased_well_1", the Radius keyword means the inner radius of fluid pipe.
Notes •If a variable radius along the well is required use Radius_distribution.
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| Radius_distribution Well radius distribution |
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Defines the well radius at each point defining the well. In thermal applications, if Heat_model equals "Constant", the Radius keyword means the outermost wellbore radius. If the Heat_model equals "Cased_well_1", the Radius keyword means the inner radius of fluid pipe.
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| Flow_model Defines well flow model |
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The well flow model is described by q=Kdp/dx, where the conductivity K is determined according to the chosen constitutive model. Note that q refers to the fluid flux, not the volumetric flow rate. Valid models are: • 3 - Hydrostatic prescribed based on surface pressure (default)
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| Leakoff_model Defines well leakage model |
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The well leakage model describes the conductivity type that is associated with the pressure drop from the well to the matrix. Valid models are: • 0 - No leakoff model (default)
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| Well_temperature Defines a constant well temperature |
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Defines well temperature (constant for every segment of well).
Notes •If a variable temperature along the well is required use Well_temperature_distribution.
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| Well_temperature_distribution Well temperature distribution |
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Defines the well temperature at each point defining the well.
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| Surface_temperature Defines a well surface temperature |
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Defines the well surface temperature for wells in which temperature is solved.
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| Initial_temperature Defines initial well temperature |
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Defines the initial well temperature.
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| Initial_time Initial time for the well thermal analysis |
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This is required when using any of the following Radial_heat_model: •Model_1 (Ramey) •Model_2 (Hasan)
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| Output_level Defines level detail of well information to be printed in res file |
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This flag determines the level of detail of well information (pressure/flow rates) to be printed in res file. Valid output modes are: • 0 - No output of well data to .res file • 1 - Standard output of well data to .res file • 2 - Detailed output of well data to .res file
For the different output levels the information output in the .res file is: Standard Output (1) •Pressure: Well number, Surface Pressure, Bottomhole Pressure, Surface Matrix Pressure, Bottomhole Matrix Pressure •Flow Rates: Well number, Surface Flow Rates, Bottomhole Flow Rates
Detailed Output (2) •Pressure/Flow Rates: Node, Well Depth, Well Status, Fluid Pressure, Matrix Pressure, Flow Rate •Fluid Conductivity: Segment, Status, Well Conductivity, Leakage Conductivity
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| History_summ_frequency Defines the time output frequency for well summary history |
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Defines the time output frequency for well summary history . Valid output values are: • 0 - No output of well summary history • 10 - Output every n steps, e.g. 10 steps as defined here •-1 - Output at the end of a stage
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| History_summ_time Output time frequency for well summary history |
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Defines the time between two consecutive outputs of screen well summary history.
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| History_summ_name Name of well summary history file |
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Defines the name of the output file containing the well summary history data. If not defined the default name is defined using the project name and the well name.
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| History_reinit_flag History reinitialization flag |
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Defines whether the history file should be reinitialised. By default the history file will be created when the well is initially defined, and data will be appended for each following stage. Definition of this keyword in a well update; e.g. to open a well from "shut" or "casing" status, allows the previous well history to be cleared. Valid models are: • 0 - Do not reinitialise history • 1 - Reinitialise history
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| Heat_model Defines well heat model |
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The well heat model defines the type of thermal properties to be prescribed on the well: • "None" - Not solving for thermal field • "Constant" - Constant heat transfer coefficient • "Cased_well_1" - Well with prescribed conduction and convection properties
Notes •If "None" is specified, then the thermal field will not be solved for. |
| Radial_heat_model Defines radial heat model |
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Defines the radial heat model used to compute the background rock temperature distribution in radial direction away from the well: • "Model_1" - Use far field temperature as reference according to Ramey (1962) • "Model_2" - Use far field temperature as reference according to Hasan (2012) (Default) • "Model_101" - Use current surrounding temperature
References •Ramey, H.J., 1962, Wellbore heat transmission, Journal of Petroleum Technology •Hasan, A.R., Kabir, S., 2012, Wellbore heat-transfer modeling and applications, Journal of Petroleum Science and Engineering |
| Radial_flow_model Defines radial flow model |
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Defines the radial flow model used to compute the pore pressure surrounding the well: • "Peaceman" - Compute volumetric flow rate for each background node according to the radial distance between the well and background nodes • "Standard" - Default. Compute pore pressure or volumetric flow rate according to proximity interpolation factor
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| Flow_skin_factor Skin factor to be used in Peaceman model |
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The skin factor s, is a dimensionless parameter in reservoir engineering that quantifies the impact of near-wellbore conditions on fluid flow. It accounts for various factors, such as formation damage, which increases flow resistance due to reduced permeability, and well completion techniques, which alter flow resistance and permeability near the wellbore. The skin factor also reflects the impact of stimulation treatments like hydraulic fracturing, which improve flow conditions.
Additionally, it adjusts for reservoir heterogeneities, ensuring accurate flow rate predictions. In ageing wells, the skin factor models changes in near-wellbore conditions over time, aiding in precise long-term reservoir management. Typically, positive s indicates increased flow resistance. The default value is 0.
Notes •Flow_skin_factor is only applicable when Radial_flow_model is defined as "Peaceman". It will be ignored if defined for the "Standard" model.
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| Well_type Well type |
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Defines the well type: • "U_shaped" - U_shaped closed loop well • "Injector" - Injector well • "Producer" - Producer well
Notes •If "U_shaped" type is selected, the output well point is allowed to be on the same depth level as the injection well point. •Well_type must be defined in conjunction with use of Surface_pressure well loading.
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