KRGR

Recognised by the OPM Flow parserPROPS

Part of the ENDPOINT_SPECIFIERS keyword family in the OPM Flow parser.

KRGR defines the scaling parameter at the relative permeability of gas at residual oil saturation (1 – SOGCR), or critical water saturation in a gas-water run (Swc), for all the cells in the model via an array. The ENDSCALE keyword in the RUNSPEC section should be activated to enable end-point scaling and the use of this keyword. The SCALCERS keyword in the PROPS section defines the options used in the re-scaling process, the options are two point scaling and three point scaling.

Notes:

The number of entries should correspond to the NX x NY x NZ parameters on the DIMENS keyword in the RUNSPEC section, unless the BOX keyword defines a sub area of the grid, in which case the total number of entries should correspond to the number of cells defined by the BOX statement.

The keyword is terminated by a “/”.

Note this the directional independent version of the keyword used with the end-point scaling option. If directional end-point scaling has been activated then the KRGRX± , KRGRY± and KRGRZ± series of the keywords should be used.

When the KRGR keyword is present in the input deck then the scaling matches the relative permeability at the critical saturation of the displacing phase (oil or water).

If three point scaling option has been selected via the SCALECRS keyword in the PROPS section the critical displacing phase is defined as:

No

Phases Present

Critical Saturation

1

Gas-Oil

S critical = 1.0 – SOGCR - SWL

2

Gas-Oil-Water

S critical = 1.0 – SOGCR - SWL

3

Gas-Water

S critical = 1.0 – SWCR

Table 8.76: Critical Displacement Relationships

End-point scaling allows the entered relative permeability functions to be re-scaled based on the saturation end-points allocated to each cell by the SWL, SWCR, SWU, SGL, SGCR, SGU, SOWCR, and SOGCR saturation grid arrays for the saturation end-points, In addition end-point scaling may be directional dependent in which case the directional dependent versions of the aforementioned arrays should be used, that is SWUX, SWUY and SWUZ instead of SWU, There is also the facility to make the directional end-point scaling reversible or non-reversible and if the non-reversible option is selected the non-reversible versions of the aforementioned arrays should be used, that is SWUX, SWUX-, SWUY, SWUY-, SWUZ and SWUZ-, instead of the SWU keyword.

End-point scaling also allows the entered relative permeability functions to be scale on the relative permeability values using the KRG, KRGR, KRO, KRORG, KRORW, KRW and KRWR relative permeability grid cell arrays for the relative permeability end-point data. In addition end-point scaling may be directional dependent in which case the directional dependent versions of the aforementioned arrays should be used, that is KRGRX, KRGRY and KRGRZ instead of KRGR, There is also the facility to make the directional end-point scaling reversible or non-reversible and if the non-reversible option is selected the non-reversible versions of the aforementioned arrays should be used, that is KRGRX, KRGRX-, KRGRY, KRGRY-, KRGRZ and KRGRZ-, instead of the KRGR keyword.

If the hysteresis model option has been activated on the SATOPTS keyword in the RUNSPEC section, then the equivalent imbibition arrays suffixed with the letter I, for example IKRGR, can be used to define the KRGR for the relative permeability imbibition tables.

Parameters

Example

The first example defines an input box for the whole grid and for layers one to three, for layer one KRGR is set equal to 0.500, for layer two KRGR equals 0.570, and for layer three KRGR equals 0.580.
--
-- DEFINE INPUT BOX FOR EDITING INPUT ARRAYS (NX=100, NY=100)
--
-- ---------- BOX ---------
-- I1 I2 J1 J2 K1 K2
BOX
1* 1* 1* 1* 1 3 / DEFINE BOX AREA
--
-- SET KRGR VALUES FOR THREE LAYERS IN THE MODEL
--
KRGR
10000*0.500 10000*0.570 10000*0.580 /
--
-- DEFINE END OF INPUT BOX EDITING OF INPUT ARRAYS
--
ENDBOX
The next example does exactly the same thing using the EQUALS keyword instead.
--
-- ARRAY CONSTANT ---------- BOX ---------
-- I1 I2 J1 J2 K1 K2
EQUALS
KRGR 0.5000 1* 1* 1* 1* 1 1 / KRGR FOR LAYER 1
KRGR 0.5700 1* 1* 1* 1* 2 2 / KRGR FOR LAYER 2
KRGR 0.5800 1* 1* 1* 1* 3 3 / KRGR FOR LAYER 3
/
| No | Phases Present | Critical Saturation            |
|----|----------------|--------------------------------|
| 1  | Gas-Oil        | S critical = 1.0 – SOGCR - SWL |
| 2  | Gas-Oil-Water  | S critical = 1.0 – SOGCR - SWL |
| 3  | Gas-Water      | S critical = 1.0 – SWCR        |

Manual source: parts/chapters/subsections/8.3/KRGR.fodt