WELL_DATA

The WELL_DATA block is used to set up a production or injection well in the model. WELL_DATA wells can be given several targets in terms of bottom hole pressure, surface volume flow rates or mass flow rates, and the well will automatically switch to the most restrictive mode when it is solved.

Below an example of a well definition:

WELL_DATA injg
  CIJK_D   25 1 50 55
  DIAMETER 0.1524 m
  WELL_TYPE GAS_INJECTOR
  INJECTION_ENTHALPY_P  120 Bar
  INJECTION_ENTHALPY_T  45 C
  BHPL     400    Bar
  SHUT
  DATE 1 JAN 2025
  OPEN
  TARG_GM 1.0 Mt/y
  DATE 1 JAN 2045
  SHUT
END

The instructions above define an injector initially shut, which starts injecting 1 Mt of gas in Jan 2025. Injection continues until Jan 2045 when the well is shut again. The energy of the fluid being injected is defined specifying a pressure and a temperature.

The options and setting supported by WELL_DATA are listed below:

WELL_TYPE

Defines the type of wells. Options are:

  • PRODUCER (This implies a multi-phase producer)

  • OIL_INJECTOR

  • GAS_INJECTOR

  • WATER_INJECTOR

  • SOLVENT_INJECTOR

Rate Target Options

Different targets can be given, these are grouped by type below.

For surface volume rate targets the options are:

  • TARG_OSV: Oil surface volume rate

  • TARG_GSV: Gas surface volume rate

  • TARG_WSV: Water surface volume rate

  • TARG_SSV: Solvent surface volume rate

  • TARG_LSV: Liquid (sum of oil and water) surface volume rate

For mass rate targets the options are:

  • TARG_OM: Oil mass rate

  • TARG_GM: Gas mass rate

  • TARG_WM: Water mass rate

  • TARG_SM: Solvent mass rate

Other targets:
  • TARG_RV: Well reservoir volume target

The liquid target only applies to a producer.

CIJK_D

This keyword takes four compulsory arguments: I, J, KL, and KU. It requests the creation of a set of well completions in the column of cells from cell I,J,KL to cell I,J,KU.

CIJK_D <I> <J> <KL> <KU>

CIJK_D counts K-indices from the top of the reservoir downwards.

  • <I> = I-location of the set of well completions (GRDECL grid format)

  • <J> = J-location of the set of well completions (GRDECL grid format)

  • <KL> = K-Lower index (from the top) of the set of well completions (GRDECL grid format)

  • <KU> = K-Upper index (from the top) of the set of well completions (GRDECL grid format)

More than one CIJK_D keyword can be entered, to specify completions in different columns.

See example below:

CIJK_D      15  50    31  36
CIJK_D      15  51    37  40

An additional argument can be added for each set of completions to specify the drilling direction, options are:

  • X (alias DIR_X)

  • Y (alias DIR_Y)

  • Z (alias DIR_Z)

For example to specify an horizontal well with two completions in the Y direction:

CIJK_D  15  50  36   36   Y
CIJK_D  15  51  36   36   Y

If the drilling direction is not specified, it will default to Z.

The CIJK_D keywords may be placed after TIME or DATE. New completions will become active from the TIME at which they are defined. So entering data like:

TARG_OSV 32000 m^3/day
CIJK_D 10 10  3  3
TIME 1000 d
CIJK_D 10 10  2  2
TIME 2000 d
CIJK_D 10 10  1  1

will produce results in which the effect of the extra completions on the gas production rate can be seen, as shown below:

../../../_images/well_data2.png

For PFLOTRAN advanced users, a CIJK card (or its alias CIJK_Z) is also available, for which the K-index counts upwards from the bottom of the reservoir.

OPEN

When a well is defined, it is normally opened. However, SHUT may be used to shut the well, and it will then remain shut until a subsequent OPEN keyword is processed.

SHUT

SHUT a well. This effectively removes it from the simulation until an OPEN is encountered.

RADIUS

The radius of the well. Currently only a single value per well is supported. Note that a unit is required.

An example is:

RADIUS 0.0762 m

If not enter the radius default to 0.1524 m.

DIAMETER

The diameter of the well. Currently only a single value per well is supported. Note that a unit is required.

An example is:

DIAMETER 0.05 m

If not entered the diameter defaults to 0.3048 m.

SKIN_FACTOR

The skin factor for the well. The default is no skin. Currently only a single value per well is supported.

THETA_FRACTION

The angle seen by the well. This factor is normally set to its default of 1.0. In some cases a different value might be used – for example at the corner of a repeated pattern study a value of 0.25 might be required.

CONST_DRILL_DIR

Defines the drilling direction for the entire well, if this changes by completion, specify this direction in CIJK_D.

The default drilling direction is in the Z vertical direction. The options available with this keyword are X_DIR, Y_DIR and Z_DIR, with the default being Z_DIR. The effect of the drilling direction upon the completion connection factor calculated for the well is detailed in the Theory Manual in the Well Model section.

BHPL

The bhp limit. This is a minimum bhp for a producer and a maximum bhp for an injector. Note that the units are specified. An example is:

BHPL
689.4757 Bar

D_REF

This over-rides the default BHP reference depth, which is the depth of the shallowest completion. Units are required.

Z_REF

This over-rides the default BHP reference depth, which is the depth of the shallowest completion. This is similar to D_REF, but is specified as an elevation rather than a depth. So a reference depth of 3000 meters would be entered as 3000 m with D_REF, but -3000 m with Z_REF. Units are required.

INJECTION_ENTHALPY_P

This specifies the pressure used to calculate the specific enthalpy of the injected fluid. Units are required. Needed only for thermal problems.

INJECTION_ENTHALPY_T

This specifies the temperature used to calculate the specific enthalpy of the injected fluid. Units are required. Needed only for thermal problems.

DATE

This specifies the date at which following well settings become effective. Example:

DATE 1 JAN 1993

The use of DATE is discussed in scheduling well operations.

TIME

This specifies the time at which following well settings become effective. An examples is:

TIME 2 y

Units are required. The use of TIME is discussed in scheduling well operations.

MULTPI

Allows all the completion connection factors to be multiplied by a factor.

GC_WEIGHT

Set the weight for this well in the group control. Default is the sum of the well completion connection factors.

Users are strongly advised not to mix default values and set values in a group.

Scheduling well operations

There must be only one WELL_DATA block for each well. Within the WELL_DATA block a series of well operations may be defined. It is possible to set the time in the run schedule at which these operations occur. An example is:

WELL_DATA injg

  RADIUS 0.0762 m
  CIJK_D 1 1 1 1
  WELL_TYPE SOLVENT_INJECTOR
  BHPL
  689.4757 Bar
  SHUT

  TIME 2 y
  OPEN
  WELL_TYPE WATER_INJECTOR
  TARG_WSV 1907 m^3/day

  TIME 3 y
  WELL_TYPE SOLVENT_INJECTOR
  TARG_SSV 339802 m^3/day

END

In this case a well called ‘injg’ is completed in the top corner cell (1,1,1). A bhp limit is set, but rather than start operating immediately, the well is shut. The well remains shut for 2 years, and then is opened as a water injector. At 3 years the well is converted into a solvent injector. This is the first part of a water alternating gas injection sequence.