NEW KEYWORDS AND OPTIONS ADDED TO IMEX 1999.10 Input/Output Control
User block addresses (UBA) are used throughout the output file. No longer are block addresses printed out in packed storage or complete storage format. UBA: I, J, K format is used consistently throughout the printout.
Command Line Options:
IMEX has several new command line options.
`-wait' Wait for License
If all available licenses are being used, this argument keeps the process in a ‘sleep’ mode until a license is available (up to 72 hrs).
`-dd' Data Directory
Simulator output files are created in the directory where the data files are specified. This can be different from the current directory where the executable resides. Include files are assumed to be in the same directory as data.
`-wd' Working Directory
Simulator output files are created in the specified working directory.
Data files reside either in the current directory or in a directory specified by the ‘ -f ‘ command line argument. Include files are assumed to be in the same directory as data.
*PVTSETN
IMEX has added the following variable to the res_list for both *OUTPRN
*RES and *OUTSRF *RES.
*FLUXSC, *FLUXRC, *VELOCSC, *VELOCRC,
IMEX has added the following variables to the grid_list for OUTSRF *GRID.
The above keywords allow RESULTS to plot velocity and flow vectors on top of displayed properties. The above can also be displayed for each direction, but their primary purpose is for the generation of flux/velocity vectors.
*POROS, *PERM, *KRSETN
IMEX has added the following variables to the grid_list both *OUTPRN
*GRID and OUTSRF *GRID. *PERM displays permeability at each desired output time, permeability is now a function of pressure and so varies with time.
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*WSRF *SECTOR
Lease line output to the SR2 system has been added. It is controlled by the
*SECTOR frequency of SR2 output.
Reservoir Description
Note: Grid Module keywords appearing in the Well or Recurrent Data section between two
*DATE or *TIME cards must be grouped together. Failure to do so could allow the Grid Module to read only part of the data. The cards in question are *TRANSI, *TRANSJ,
*TRANSK, *TRANLI, *TRANLJ, *TRANLK, and *REFINE (RANGE).
The Grid Module has generally been sped up for most cases and now has improved tolerance of odd corner point grids. Refined corner point grids are now allowed.
In addition, the algorithms for handling the connections made by sloping faults has been rewritten and improved.
The method for handling transmissibility multiplier inheritance to refined grids has been improved.
The handling of reservoir porosity versus pressure has been greatly extended in the IMEX simulator. Multiple rock regions have been added as well as the use of pressure tables for both porosity and permeability (vertical and horizontal) multipliers.
In addition the modelling of porosity and permeability hysteresis and irreversibility vs. pressure allows IMEX to model compaction. See the keywords *CROCKTYPE, *CROCKTAB,
*CROCKTABH, *IRREVERS, *CCPOR, *CPRPOR and *CTYPE for a complete explanation.
Component Properties
IMEX includes significant additions to the Component Property section.
A gas-water (2-equation subset) has been added to IMEX. This allows a simpler data input format to model gas-water problems as well as reduced execution times to run gas-water problems. It is no longer necessary to enter fictitious oil properties to model gas-water systems. Only gas and water properties need be entered. Gas-water component properties keywords are listed below:
*MODEL *GASWATER
This keyword signals IMEX to use the 2-equation gas-water model subset of the black-oil equations.
*PVTG
This keyword is used to input a gas PVT table (for use with GASWATER option). Gas formation volume factor (Bg, Eg, or Zg) and gas viscosity are tabulated against pressure.
Rock-Fluid Model
*SWT, *SLT, *SGT
The gas-water option triggers slightly different input in each of the above tables. The tables no longer require input of either Krow or Krog. Pcow is replaced by Pcgw. Pcog is not entered.
User's Guide IMEX Introduction • 39
The gas relative permeability hysteresis option and the Pcow hysteresis options have been reviewed and improved. MXSMO024.dat has been added to the template directory to highlight the Pcow hysteresis option. This new template duplicates the radial test example in J.E. Killough's classic paper "Reservoir Simulation with History-Dependent Saturation Functions", SPEJ, Feb. 1976, pp. 37.
Initialization
The Initialization section has no obvious changes, but the gas-water option allows the user to use the option:
*VERTICAL *BLOCK_CENTER *WATER_GAS
when nonzero Pcgw is entered in the *SWT table. Previous versions of IMEX forced the user to use:
*VERTICAL *DEPTH_AVE *WATER_GAS *TRANZONE *ON
to model gas-water capillary pressure. It is still required to use the
*TRANZONE *ON option with the *GASWATER option when
*DEPTH_AVE initialization is required.
Well and Recurrent Data
IMEX includes a significant modification to the well module simulator interface. This modification allows the well module better access to simulator information. This in turn allows the well module to more accurately calculate well and group operating constraints.
As a consequence of the above, the *CONT *REPEAT subkeywords on operating and monitor constraints are now operational. In addition, the well gravitational head calculation has been moved to a position within the code which ensures the well module and the simulator use identical heads.
Improvements have been made to how the well module extrapolates tubing head pressure tables; more consistent results will now be obtained.
The well index printout (available when using *WPRN *WELL *ALL) has been greatly enhanced. In addition to well index, the actual layer and total well fluid productivity/injectivity is displayed.
As well as being able to display well productivity the user is now able to directly input fluid phase or total well productivity/injectivity or productivity/injectivity multipliers using the
*SETPI keyword listed below.
*SETPI
SETPI can be used to alter the well productivity to measured values or by a multiplicative factor correcting the last (*MULT) or the fundamental (*MULTO) productivity.
40 • Introduction User's Guide IMEX
*SETPI (*OIL) (*WAT) (*GAS) (*LIQ) (*TOT) (*MULT) (*MULTO)
well_list
Each time a *SETPI keyword is read, wells on the well list have their fundamental productivity corrected to match the user input value. The correction is only applied when the *SETPI keyword is read (i.e. when the test was done). Well productivity will normally change as fluids move in the vicinity of the well. However, productivities can be corrected at any later time by using the *SETPI keyword again.
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