WDFACCOR
Recognised by the OPM Flow parserSCHEDULE
WDFACCOR keyword defines the parameters to calculate a gas well’s connection D-factors (flow dependent skin factor) for each connection based on a correlation for the coefficient of inertial resistance, usually known as β, in Forchheimer’s flow equation1 Dake, L.P. Fundamentals of Reservoir Engineering, Amsterdam, The Netherlands, Elsevier Science BV (1978) Chapter 8.6, pages 252-257.,2 Geertsma, J., 1974. Estimating the Coefficient of Inertial Resistance in Fluid Flow Through Porous Media. Soc.Pet.Eng.J., October: 445-450., 3 Gewers, C.W.W. and Nichol, L.R., 1969. Gas Turbulence Factor in a Microvugular Carbonate. J.Can.Pet.Tech., April.and 4 Wong, S.W., 1970. Effects of Liquid Saturation on Turbulence Factors for Gas Liquid Systems. J.Can.Pet.Tech., October. This keyword uses Dake’s correlation to calculate the D-factor.
Dake, L.P. Fundamentals of Reservoir Engineering, Amsterdam, The Netherlands, Elsevier Science BV (1978) Chapter 8.6, pages 252-257.
Geertsma, J., 1974. Estimating the Coefficient of Inertial Resistance in Fluid Flow Through Porous Media. Soc.Pet.Eng.J., October: 445-450.
Gewers, C.W.W. and Nichol, L.R., 1969. Gas Turbulence Factor in a Microvugular Carbonate. J.Can.Pet.Tech., April.
Wong, S.W., 1970. Effects of Liquid Saturation on Turbulence Factors for Gas Liquid Systems. J.Can.Pet.Tech., October
Notes:
The keyword is followed by any number of records with each record terminated by a “/” and the keyword should be terminated by a “/”.
The simulator evaluates the connection D-factors using the following expression based on Dake’s correlation:
[D``=``A K_e^B %phi^C K_e over h 1 over r_w { %gamma_g } over { %mu_g }]
(12.3.260.1)
Where:
[K_e]= effective permeability of the grid block,
[%phi]= porosity of the grid block,
[h]= connection length,
[r_w]= wellbore radius,
[%gamma_g]= gas gravity at surface conditions,
[%mu_g]= gas viscosity at bottom hole conditions.
Note that since [%mu_g]is dependent on pressure the D-factor will also vary with pressure.
See also the WDFAC keyword in the SCHEDULE section that can be used to specify the well D-factor; and the COMPDAT keyword in the SCHEDULE section that can be used to specify the connection D-factors directly.
- Records
- One or more records, each terminated by
/ - Items per record
- 4
Parameters
| No. | Name | Description | Type | Dimension | Field | Metric | Lab | Default |
|---|---|---|---|---|---|---|---|---|
| 1 | WELLNAMEmanual: WELNAME | A character string of up to eight characters in length that defines the well name for which the well D-factor correlation is being defined. Note that the well name (WELNAME) must have been declared previously using the WELSPECS keyword in the SCHEDULE section. | STRING | None | ||||
| 2 | A | A real value greater than or equal to zero that defines the coefficient A in the D-factor correlation. | DOUBLE | Viscosity* | cP.day.ft2/ | cP.day.m2/ | cP.hour.cm2/ | 0.0 |
| 3 | B | A real value that defines the exponent B of the grid block permeability in the D-factor correlation. | DOUBLE | 1 | dimensionless | dimensionless | dimensionless | 0.0 |
| 4 | C | A real value that defines the exponent C of the grid block porosity in the D-factor correlation. | DOUBLE | 1 | dimensionless | dimensionless | dimensionless | 0.0 |
Example
In the first example the connection D-factors for gas well GP01 are evaluated for correlation coefficients specified in field units based on the laboratory determined relationship between β and the absolute permeability presented by Dake in Fig. 8.8 (variation of β with porosity has been neglected).
--
-- WELL D-FACTOR CORRELATIONS
--
-- WELL
-- NAME A B C
WEFAC
GP01 6.04E-05 -1.1045 0.0 /
/
In the second example the same correlation coefficients are specified in metric units.
--
-- WELL D-FACTOR CORRELATIONS
--
-- WELL
-- NAME A B C
WEFAC
GP01 1.20E-07 -1.1045 0.0 /
/
| [D``=``A K_e^B %phi^C K_e over h 1 over r_w { %gamma_g } over { %mu_g }] | (12.3.260.1) |
|--------------------------------------------------------------------------|--------------|Manual source: parts/chapters/subsections/12.3/WDFACCOR.fodt