`WCYCLE`

Recognised by the OPM Flow parserSCHEDULE

The WCYCLE keyword defines automatic well opening and closing cycling parameters. These are used to model for example “Huff and Puff” cyclic steam injection in heavy oil reservoirs or Water-Alternating-Gas (“WAG”) processes in enhanced oil recovery modeling. The keyword defines specific time periods for automatically cycling wells on and off. For example in a WAG scheme the water injection wells would have one set of cycling parameters and the gas injection wells another, such that only one type of well is active at a time.

Notes:

The keyword is followed by any number of records with each record terminated by a “/” and the keyword should be terminated by a “/”.

Records: One or more records, each terminated by /
Items per record: 6

Parameters

No.	Name	Description	Type	Dimension	Field	Metric	Lab	Default
1	`WELL` manual: `WELNAME`	A character string of up to eight characters in length that defines the well name for which the well automatic cycling parameters are being defined. Note that the well name (WELNAME) must have been declared previously using the WELSPECS keyword in the SCHEDULE section, otherwise an error may occur.	STRING					None
2	`ON_TIME`		DOUBLE	Time				0
3	`OFF_TIME`		DOUBLE	Time				0
4	`START_TIME` manual: `ONTIME`	A real positive value that defines the length of time for the on period. The well will be turned off at the beginning of the first time step after the on period has elapsed. If ONTIME is zero or negative then the well will not be turned on by the automatic well cycling.	DOUBLE	Time	day	day	hour	0.0
5	`MAX_TIMESTEP` manual: `OFFTIME`	A real positive value that defines the length of time for the off period. If the well was turned off by automatic cycling then it will be turned on at the beginning of the first time step after the off period has elasped. If the well was turned off other than by automatic cycling then the well will remain turned off. If OFFTIME is zero or negative then the well will not be turned on by the automatic well cycling.	DOUBLE	Time	day	day	hour	0.0
6	`CONTROLLED_TIMESTEP` manual: `STARTTIME`	A real positive value that defines the length of time for the start-up period during which the well efficiency factor will be ramped up. The start-up period begins at the start of the on period. The well’s efficiency factor is ramped up linearly from zero at the start of the on period to the value specified previously by the WEFAC keyword after the start-up period has elasped. The well efficiency factor to apply during each time step is linearly interpolated based on the time at the end of the time step. If the time step size is small compared with STARTTIME then the rate will be ramped up gradually. Whereas, if the time step size is greater than STARTTIME then the rate will ramp up instantaneously potentially causing convergence problems.	STRING		day	day	hour	0.0
7	`MAXTS`	A real positive value that defines the maximum time step length when the well is turned on by automatic cycling. This overrides the standard maximum time step length. This can help to reduce potential convergence problems caused when a high rate well is opened. If MAXTS is zero then the standard maximum time step length applies.			day	day	hour	0.0
13	`CTRLTS`	A defined character string that specifies whether the time steps should be controlled to coincide exactly with the automatic cycling times for this well. CTRLTS should be set to one of the following: YES: time steps are controlled to coincide exactly with the automatic cycling times for this well. Note this will exactly match the specified on and off periods for this well. However, this is likely to reduce the time step size, especially if this option is set for a number automatic cycling wells that have different parameters. NO: time steps are not controlled to coincide exactly with the automatic cycling times for this well. Note this is unlikely to match the specified on and off periods for this well unless they coincide with the report steps. The next period will start at the next time step after the current on/off period has elasped. Therefore, the on/off periods are likely to be longer than specified.						NO

Example

The following example defines the cycle lengths for a Water-Alternating-Gas injection scheme with a water-gas slug length ratio of 1:2, and initiates automatic cycling in the water injection well. A maximum time step of 5 days has been specified following the start of each injection period. The simulation then proceeds to the end of the first water injection cycle when automatic cycling is initiated in the gas injection well.
--
-- AUTOMATIC CYCLING OF WELLS ON AND OFF
--
WCYCLE
--WELL ON OFF STARTUP STARTUP CTRL
--NAME PERIOD PERIOD TIME MAXTS TIMESTEP
I01W 30.0 60.0 1* 5.0 YES /
I01G 60.0 30.0 1* 5.0 YES /
--
-- OPEN WELLS
--
WELOPEN
--WELL OPEN
--NAME SHUT
I01W OPEN /
I01G SHUT /
/
--
-- REPORT STEPS
--
TSTEP
30.0 /
--
-- OPEN WELLS
--
WELOPEN
--WELL OPEN
--NAME SHUT
I01G OPEN /
/
Note that the wells initially need to be opened manually in order to start the automatic cycling. In addition, this needs to be done at the correct times to ensure that the water and gas injection wells are syncronised.

Manual source: parts/chapters/subsections/12.3/WCYCLE.fodt