NOTES FOR IMEX 2006.10
1. Seawater/Scale Buildup Option 2. TRIGGER Action Option
3. Improved Parallelization Performance using *JACDOMS 4. Well Definition Order Relaxed/Improved
5. *WLISTSHUT/*WLISTOPEN Option
6. *WTMULT/*GCONIMULT/*GCONPMULT Options 7. Improvements to Tubing Head Pressure Calculations 8 *WOC_SW available with *DEPTH_AVE Initialization.
9. Reinfiltration Modeling for Fractured Reservoirs (Beta) 10. Binary File Reading Option
11. DPCONNECT
Seawater Injection/Scale Buildup Option
A Seawater Injection/Scale buildup option has been incorporated in IMEX. This feature is actually made up of two independent options: 1) a Seawater Injection Tracking Option and 2) a Scale Buildup/Well Damage model. The two models can be coupled to make well damage a function of both water rate and the fraction of seawater in the produced water.
The Seawater Injection option adds a seawater flow equation to the normal Black Oil or Oil Water Models in IMEX. This equation is solved simultaneously with the oil, water and gas flow equations. It is an active model, and the injected water may have a viscosity different from formation water. Thus it is possible to model seawater injection altering fluid flow patterns within the reservoir. This model and the Scale Buildup/Well Damage model are coupled through the *SCLDPS table (Scale Buildup/Well Damage Option) which relates scale deposition to the volume fraction of seawater in the produced water. The Seawater Option is controlled by the following new keywords:
1. *MODEL *BLACKOIL_SEAWATER Component Properties
2. *MODEL *OILWATER_SEAWATER Component Properties
3. *OUTPRN/*OUTSRF *GRID *SEAWATFRC Input/Output Control 4. *CONVERGE *MAXRES *SEAWATER Numerical Methods Control
5. *INCOMP SEAWATER Well and Recurrent Data
6. *ALTERFS Well and Recurrent Data
The Scale Buildup/Well Damage Model allows the user to model well (layer) productivity damage based on the amount of water produced through each layer of a well. Optionally the damage can be made a function of the fraction of seawater produced with formation water.
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This Option is controlled by the following new keywords:
1. *SCLDPS Rock Fluid Data
2. *SCLDMG Rock Fluid Data
3. *SCLTBL-WELL Well and Recurrent Data
4. *SCLTBL-LAYER Well and Recurrent Data
5. *SCLRMV-WELL Well and Recurrent Data
6. *SCLRMV-LAYER Well and Recurrent Data
The Scale Buildup/Damage model can be used with any Property model available in IMEX (for example: API Tracking, Solvent, and Gas-water). It is only with the *BLACKOIL_SEAWATER and *OILWATER_SEAWATER models that the active seawater equation can be used to make scale formation a function of seawater fraction produced.
Trigger Action Option (Well and Recurrent Data)
This keyword allows for certain actions to be implemented when a specified condition or trigger is satisfied. The actions are specified in the form of a block of valid keywords encapsulated within the *TRIGGER and *END_TRIGGER keywords.
The trigger condition of each active trigger is tested at the bottom (end) of the time step (that is after the time step is considered to be completed, the cumulatives have been updated and the simulation is ready to proceed to the next time step). If the trigger condition is satisfied then the list of associated actions are processed at the top (beginning) of the next time step.
The order of the triggers in the trigger list depends entirely on the sequence on which the triggers are defined. The triggers are not sorted in any other way.
It is possible to nest triggers by including the definition of the ‘inner’ trigger within the keyword set of the ‘outer’ trigger (that is before specification of the *END_TRIGGER keyword of the ‘outer’ trigger). Please see the *TRIGGER Keyword in the Well and Recurrent Data Section for a complete description of the option.
*JACDOMS Parallelization Option (Numerical Methods Control)
*JACDOMS (-jacdoms on the command line) enables a new technique to control the Jacobian domains used for parallelization. This technique is generally more efficient than those previously used to control Jacobian Domains (controlled using the *DPLANES or
*DTYPE keywords) and is recommended.
More Flexible Well Definition Ordering (Well and Recurrent Data)
It is now possible to define a well, name it, and specify its group affiliation with a *WELL keyword at one time, specify its completions with *PERF at a later time, and finally define the well’s type with *PRODUCER or *INJECTOR at a still later time and have the well become active. Previously it was necessary to define a well’s type (injector or producer) immediately after its initial definition.
*WLISTSHUT, *WLISTOPEN (Well and Recurrent Data)
*WLISTSHUT and *WLISTOPEN provide a means to temporarily shut a large list of wells and later re-open them without disturbing the pattern of shut and autodrillable wells that existed when the *WLISTSHUT keyword was read.
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*WTMULT (Well and Recurrent Data)
*WTMULT allows modification of any previously specified well constraint value for well(s) listed by well_numbers or 'well_names' by applying a multiplying factor.
*GCONIMULT, *GCONPMULT (Well and Recurrent Data)
*GCONIMULT is used to specify multipliers which modify existing group injection target controls. *GCONPMULT is used to modify existing group production target controls with the use of multipliers.
Mechanistic/Momentum Wellbore Pressure Drop Model Improvements
The Mechanistic Wellbore pressure drop calculation in IMEX (*HEAD-METHOD …
*MODEL-MOMENTUM) has been made more rigorous. The updated Momentum option is currently a full implementation of the Petalas-Aziz mechanistic model.
*WOC_SW in the *DEPTH_AVE Vertical Equilibrium Initialization Option
*WOC_SW allows the user to specify non-zero oil saturation below the water oil contact.
Small non-zero water zone oil saturation is often useful in avoiding convergence difficulties if oil attempts to move into the water zone. Previously, when this option was required it was necessary to use *BLOCK_CENTER initialization.
Reinfiltration Model for Fractured Reservoirs (Beta - no Builder Support or Manual Entries)
The Subdomain-Dual Permeability-Reinfiltration (SD-DK) model is controlled by the following Keywords,
*SUBDOMAIN turns on subdomain dual porosity model,
*FRACVOL controls subdomain block thickness,
*TRANSD controls SD-DK inter-subdomain connections, and
*SD_REINF determines if SD-DK inter-subdomain connections are used to represent reinfiltration or gravity drainage.
Modeling capabilities include:
1. Standard Subdomain Model
If the *TRANSD keyword is not included in the model, *SD_REINF is not required and the model reverts to the standard *SUBDOMAIN model. It is still an excellent idea to use the new *FRACVOL keyword to minimize the error in the capillary holdup.
2. Gravity Drainage between Subdomains
Using the *TRANSD keyword to set non-zero transmissibility multipliers between domains allows the fluid in the bottom of a matrix subdomain to flow into the top of the matrix subdomain directly below it without having to flow into the fracture first. In essence this is a hybrid method which combines the Subdomain model and the Dual Permeability model and gives similar results. As there is no capillary holdup in the matrix, using *FRACVOL does not significantly improve the models results. As *TRANSD is grid block dependent, gravity drainage between
subdomains can be modeled in user specified regions of the reservoir.
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3. Reinfiltration between Subdomains.
As in 2) the non-zero *TRANSD keyword enables inter-subdomain flow. The use of *FRACVOL and *SD_REINF together enables the use of the bottom-most subdomain block as a proxy for a horizontal fracture between the subdomains.
*FRACVOL is used to reduce the thickness of the bottom division of the subdomain which reduces the amount of fluid stored in the fracture proxy block and minimizes the error in capillary holdup.
*SD_REINF = 1.0 sets the bottom subdomain division’s capillary pressure to 0.0 (the fracture’s value) and introduces a real capillary discontinuity in the flow between the two subdomains. *SD_REINF is grid block dependent.
4. Gravity Drainage and Reinfiltration between Subdomains
Actual drainage from Subdomain blocks is a combination of gravity drainage and reinfiltration. This may be approximately accounted for by scaling back the bottom subdomain division’s capillary pressure rather than setting it explicitly to zero.
This can be accomplished by setting *SD_REINF to a value between 0.0 and 1.0.
The fracture proxy block’s capillary pressure is scaled by 1.0 - *SD_REINF.
See the document “SD-DK with Reinf.doc” in the DOC directory of your IMEX 2006.10 install directory for more details.
Binary File Reading Option
Normally Builder writes data in text-format files. However, Builder is able to write some grid definition and property data in binary form to a separate binary-format file. This option is invoked in Builder via menu "File/Save As.../Array Saving Method/Binary File Format (*.cmgbin)". The binary file is saved in the same folder as the main dataset file and given the same root name but extension “.cmgbin”. Unlike the *INCLUDE facility which can involve multiple include files, there is at most one binary format file associated with a main data file.
When the simulator detects subkeyword *BINARY_DATA in its initial data scan, it opens the associated binary file which is assumed to have the same root name as the main data file but extension “.cmgbin”. Each time the simulator encounters *BINARY_DATA during the data loading pass, it locates that property in the binary file and reads one value for each block in the grid, similar to the *ALL option. A mismatch between the text and binary parts of the data set will result in an error.
The reading of binary data is much faster than text and so for large models can speed up significantly data reading in the simulator. Text formatted data can differ slightly in value from its associated binary data, so text and binary versions of the same data may give slightly different simulation results.
*DPCONNECT Option
The DPCONNECT keyword allows the grid module to produce extra connection between blocks in a dual porosity/permeability system when either the matrix or the fracture is missing from one of the two blocks being connected.
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When enabled, a dual porosity or dual permeability block with a missing fracture will connect the matrix to both the matrix and fracture of surrounding blocks. In addition a dual porosity or dual permeability block with a missing matrix will connect the fracture to both the matrix and fracture of surrounding blocks.
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