ECLIPSE_FILE

The ECLIPSE_FILE sub-block of OUTPUT requests that the simulation outputs Eclipse format files. See example below:

OUTPUT
  MASS_BALANCE_FILE
    PERIODIC TIMESTEP 1
  END
  ECLIPSE_FILE
    PERIOD_SUM TIMESTEP 1
    PERIOD_RST TIME 200 d
    TIMES d 30 500 1000
    DATES  1 JAN 2023    1 JAN 2024   1 JAN 2025
    WRITE_DENSITY
    OUTFILE WCT
    SUMMARY_D
      [...]
    END_SUMMARY_D
    FLIP_Y
    WRITE_COMPR
  END
  LINEREPT
END

The default is to output unformatted unified Eclipse files that are compatible with post-processors such as Stratus or ResInsight, an open-source post-processor. Five Eclipse files are produced – a grid file (.GRID), an init file (.INIT), a specification file (.SMSPEC), a summary file (.UNSMRY) and a restart file (.UNRST). The restart files are only used as an industry standard output format by Cirrus – they cannot be used to restart an Eclipse run.

The summary files contain a set of standard mnemonics from which line graphs may be obtained, such as FGIP and WGIR. For the full list of available variables and their names refer to Line Graph Mnemonic.

The init and restart files contain grid and solution properties such as permeabilities and fluid saturations.

The user specifies the report times at which the Eclipse restart file is updated by using one or a combination of the following options: TIMES, DATES and PERIOD_RST.

Below are all the keywords supported within ECLIPSE_FILE:

Note that for ResInsight to load data correctly, the input name must be in capital letter (e.g. CASE.IN) so that output files will also be in capital letter (CASE.GRID, CASE.UNRST, CASE.SMSPEC, CASE.UNSMRY, CASE.INIT)

PERIOD_SUM

PERIOD_SUM controls the frequency of the summary file (line graph data) output. This may be done by timestep (TIMESTEP), or by time period (TIME).

Below is an example asking to update the summary file at each time step:

OUTPUT
  ECLIPSE_FILE
      PERIOD_SUM TIMESTEP 1
      DATES  1 NOV 2017   1 JAN 2018   1 JAN 2020   1 JAN 2021   1 JAN 2022
  END
  LINEREPT
END

And an example asking to update the summary file every 5 days:

OUTPUT
  ECLIPSE_FILE
      PERIOD_SUM TIME 5 d
      DATES  1 NOV 2017   1 JAN 2018   1 JAN 2020   1 JAN 2021   1 JAN 2022
  END
  LINEREPT
END

DATES

Used within the ECLIPSE_FILE instruction block to ask the simulator to output ECLIPSE restart files at given dates. See example below:

OUTPUT
  ECLIPSE_FILE
      PERIOD_SUM TIMESTEP 1
      DATES  1 NOV 2017   1 JAN 2018   1 JAN 2020   1 JAN 2021   1 JAN 2022
      DATES  1 JAN 2023   1 JAN 2024   1 JAN 2025   1 JAN 2026   1 JAN 2027
  END
  LINEREPT
END

Multiple DATES lines are accepted within the ECLIPSE_FILE block, and each line can take multiple dates. Each date is defined by the date format dd MMM YYYY.

TIMES

This keyword requests output of Eclipse restart and summary data at a series of specified times. For example:

TIMES y 1 2 5 10

requests output at 1, 2, 5 and 10 years.

PERIOD_RST

PERIOD_RST controls the frequency of the restart file (pressure and saturations for 3D visualisation) output. This may be done by TIMESTEP, or by TIME period in the same way as done for the summary file.

MULTIPLE

MULTIPLE requests ouput of multiple Eclipse restart files (with suffices like X0001) rather than a single unified file with a .UNRST suffix.

WRITE_DENSITY

Requests output to the eclipse file system of density.

WRITE_VISCOSITY

Requests output to the eclipse file system of viscosity.

WRITE_RELPERM

Requests output to the eclipse file system of relative permeabilities.

WRITE_CAPPRES

Requests output to the eclipse file system of capillary pressures.

WRITE_MASS_RATES

By default the simulator output rates and totals, for the entire field and wells in surface volumes. To output to the summary files also the equivalent mass quantities, this keyword must be included within the ECLIPSE_FILE block. Example below:

OUTPUT
  ECLIPSE_FILE
    PERIOD_SUM TIMESTEP 1 d
    DATES  1 NOV 2017   1 JAN 2018   1 JAN 2020   1 JAN 2021   1 JAN 2022
    WRITE_MASS_RATES
    OUTFILE
  END
  LINEREPT
END

This will output, for example, FGMPR (Field Gas Mass Production Rate), and other mass variables to the summary files. For a detailed list, please see line graph mnemonics.

FORMATTED

The default is to output unformatted unified Eclipse files, although the FORMATTED sub-keyword may be used to request formatted files. Example:

OUTPUT
  MASS_BALANCE_FILE
    PERIODIC TIMESTEP 1
  END
  ECLIPSE_FILE
    PERIOD_SUM TIMESTEP 1 d
    PERIOD_RST TIME 200 d
    FORMATTED
  END
  LINEREPT
END

OUTFILE

When included, Cirrus writes tables with the following content: mass balance, fluid in place, solution variables, and gas phase split to the .out file every time the restart file is updated. The information found in these reports are detailed in Simulation output file. Example:

OUTPUT
  ECLIPSE_FILE
    PERIOD_SUM TIMESTEP 1
    DATES  1 JAN 2023    1 JAN 2024   1 JAN 2025
    OUTFILE WCT
  END
  LINEREPT
END

OUTFILE may take one or more optional arguments (W, C and T) to specify additional output. Any combination of W, C and T may be used. Each letter specifies the following:

  • W: output of well data to the out file

  • C: output of completion data to the out file

  • T: output of timing data to the out file

More information on the data output can be found in the WELLS report and the Completion report sections

SUMMARY_D/SUMMARY_Z

This requests that cell values be written to the .UNSMRY file, so they can be plotted against time later.

SUMMARY_D and SUMMARY_Z are identical except that for SUMMARY_D the k index is downwards, and for SUMMARY_Z it is upwards.

An example usage is:

OUTPUT
  [...]
  ECLIPSE_FILE
    [...]
    SUMMARY_D
      BPR   10 10 3
      BOSAT 10 10 3
      BGSAT 10 10 3
      BWSAT 10 10 3
      BSSAT 10 10 3
      BDENO 10 10 3
      BDENG 10 10 3
      BDENW 10 10 3
      BDENS 10 10 3
      BVOIL 10 10 3
      BVGAS 10 10 3
      BVWAT 10 10 3
      BVSLV 10 10 3
      BGPC  10 10 3
      BWPC  10 10 3
      BTEMP 10 10 3
      BPBUB 10 10 3
    END_SUMMARY_D
  END
  LINEREPT
END

This requests the values of several values, all at cell 10,10,3, be written to the summary file.

The variables available are:

  • BPR, the cell pressure.

  • Phase saturations: BOSAT/BSOIL, BGSAT/BSGAS, BWSAT/BSWAT, BSSAT/BSSLV, for oil, gas, water or solvent saturation respectively.

  • Phase densites: BODEN/BDENO/BDOIL, BGDEN/BDENG/BDGAS, BWDEN/BDENW/BDWAT, BSDEN/BDENS/BDSLV, for oil, gas, water or solvent density respectively.

  • Phase viscosities: BOVIS/BVOIL, BGVIS/BVGAS, BWVIS/BVWAT, BSVIS/BVSLV, for oil, gas, water or solvent viscocity respectively.

  • Phase relative permeabilities: BKRO, BKRG, BKRW, BKRS, for oil, gas, water or solvent relative permeability respectively.

  • Capillary pressures: BGPC, BWPC, for gas and water capillary pressures respectively.

  • Mole fractions: BAMFW, BAMFG, BYMFW, BYMFG, water in aqueous, gas in aqueous, water in vapour, and gas in vapour respectively.

  • Temperature: BTEMP.

  • Bubble point: BPBUB.

The output from SUMMARY_D/SUMMARY_Z can be found in the Eclipse summary files, and also in the mass file. For example, the following:

SUMMARY_D
  BPR   1 1 100
END_SUMMARY_D

adds a summary BPRESSUR summary to block 1 1 100 in the .UNSMRY file, and the following column to the mass file:

BPressure [bar] 1_1_100

GRID

By default ECLIPSE_FILE makes Cirrus write the grid in the .EGRID format. By inserting the GRID card within the ECLIPSE_FILE block, the grid will be output using the .GRID format rather than .EGRID. See example below:

OUTPUT
  MASS_BALANCE_FILE
   PERIODIC TIMESTEP 1
  END
  ECLIPSE_FILE
    TIMES y 1 2 3 4 5 6 7
    PERIOD_SUM TIMESTEP 1
    GRID
  END
  LINEREPT
END

INIT_ALL

This keyword causes EQLNUM, Kro and the end-point (Swl) values to be writen to the INIT file.

FLIP_Y

This keyword deals with the issue that a postprocessor may chose to view the x,y,z values written to the output .GRID or .EGRID files in a left- or right-handed frame. That is, if the x-axis is taken as along the screen, the y-axis may be taken as being up or down the screen. Normally this choice is passed to the postprocessor using the GDORIENT keyword, and if this is incorrect, most post-processors (such as OGS’s Stratus program) have a control to flip between display conventions.

However, if this is not available, then the y-values in the output file may be changed using FLIP_Y. The syntax is:

FLIP_Y v units

Where v is a value, often set to 0, and units are a units of distance.

The y-coordinate value is then written out as y’, where:

y' = v - y

So if v were 1000 and units were metres:

FLIP_Y 1000 m

Then the y values on the output files would be reset as y’ = 1000 -y.

Note that this does not change the values used in the code, only those written to the output files.

WRITE_COMPR

This keyword follows the pattern of WRITE_VISCOSITY, WRITE_DENSITY etc, but writes a saturation-weighted total compressibility to the output files with the mnemonic COMPR. For example:

ECLIPSE_FILE
  WRITE_COMPR
  PERIOD_RST TIME  800 d
  OUTFILE
END

The compressibility \(C\) is given by:

\[C = \frac{1}{\phi} \frac{d\phi}{dP} + \sum_p{ \left( \frac{S_p}{\rho_p} \frac{d\rho_p}{dP} \right) }\]

Where \(\phi\) is porosity, \(P\) is pressure, \(S_p\) is saturation of phase \(p\), and \(\rho_p\) is density of phase \(p\).

The first term on the fractional increase in the cell pore volume per unit pressure rise, and the sum over phases is the fractional decrease in the volume of the fluid phases.

Phase molar density is the inverse of phase molar volume, so the usual expression for phase compressibility, \(-\frac{1}{v_p} \frac{d v_p}{dP}\), may be written:

\[-\frac{1}{v_p} \frac{d v_p}{dP} = -\rho_p \frac{d \left( \frac{1}{\rho_p} \right)}{dP} = -\rho_p \left(-\frac{1}{\rho_p^2} \frac{d \rho_p}{dP} \right) = \frac{1}{\rho_p} \frac{d \rho_p}{dP}\]

These terms are then saturation-weighted in the above expression.

Note that in saturated multi-phase systems this expression does not consider the affect of the change in the phase equilibrium point with pressure.

This keyword has no arguments.

WRITE_PHASEPRES

This keyword allows the user to request output of the phase pressures to the Eclipse restart files. The usage is:

OUTPUT
  ECLIPSE_FILE
    PERIOD_RST TIME 200 d
    WRITE_CAPPRES
    WRITE_PHASEPRES
    OUTFILE
  END
  LINEREPT
END