BRIEF DESCRIPTION OF CHAPTER 3
BASIC=2 NORST=1 /
SOLUTION
Initial equilibration conditions
Datum Pi@datum WOC Pc@WOC
EQUIL
8075 4500 8200 0 /
Output to restart file for t=0 (.UNRST) Restart file Graphics for init cond only RPTRST
BASIC=2 NORST=1 /
4.7 Output Requirements
Clearly there is no point in performing a reservoir simulation if no results are output. The parameters that should be calculated are specified in the SUMMARY section by the use of appropriate keywords, but for this section only the keywords are not found in the main section of the manual, but in the Summary Section Overview.
Most of the summary keywords consist of four letters that follow a basic convention.
1st letter:
F - field R - region W - well C - connection B - block 2nd letter:
O - oil (stb in FIELD units) W - water (stb in FIELD units) G - gas (Mscf in FIELD units)
L - liquid (oil + water) (stb in FIELD units) V - reservoir volume flows (rb in FIELD units) T - tracer concentration
S - salt concentration C - polymer concentration N - solvent concentration Figure 8.
SOLUTION Section of input data file.
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Reservoir Simulation Model Set-Up
3rd letter:
P - production I - injection 4th letter:
R - rate T - total
Thus, use of the keyword FOPR requests that the Field Oil Production Rate be output, and WWIT represents Well Water Injection Total, etc.
Keywords beginning with an F refer to the values calculated for the field as a whole, and require no further identification. However, keywords beginning with another letter must specify which region, well, connection or block they refer to. Thus, for example, a keyword such as FOPR requires no accompanying data, but WWIT must be followed by a list of well names, terminated with a /. If no well names are supplied, and the keyword is followed only by a /, the value is calculated for all wells in the model. An example would be
FOPR WWITInj /
WBHP/
Here, the following will be calculated:
• Oil production rate for the entire field
• Cumulative water injection for well “Inj”
• Well bottomhole pressure for all wells in the model
In Tutorial 1A the following parameters should be calculated and output:
• Field average pressure
• Bottomhole pressure of all wells
• Field oil production rate
• Field water production rate
• Field oil production total
• Field water production total
• Water cut in well PROD
• CPU usage
In addition, the output Run Summary file (.RSM) should be defined such that it can easily be read into MS Excel.
The form in which this data should be entered is shown in Figure 9. The following keywords are used:
SUMMARY Section header
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Reservoir Simulation Model Set-Up
WBHP Well Bottomhole pressure FOPR Field Oil Production Rate FWPR Field Water Production Rate FOPT Field Oil Production Total FWPT Field Water Production Total
WWCT Well Water Cut
CPU CPU usage
EXCEL Create summary output as Excel readable Run Summary file
SUMMARY
Field average pressure FPR
Bottomhole pressure of all wells WBHP
/
Field oil production rate FOPR
Field water production rate FWPR
Field oil production total FOPT
Field water production total FWPT
Water cut in PROD WWCT
PROD /
CPU usage TCPU
Create Excel readable run summary file (.RSM) EXCEL
4.8 Production Schedule
Having defined the initial conditions (t = 0) in the SOLUTION Section, the final part of the input data file defines the well controls and time steps (t > 0) in the SCHEDULE Section. The main functions that are performed here are:
• Specify grid data to be output for display or restart purposes
• Define well names, locations and types
• Specify completion intervals for each well
• Specify injection and production controls for each well for each given period Figure 9.
SUMMARY Section of input data file.
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Reservoir Simulation Model Set-Up
(time step)
Basic pressure and saturation data should be generated at every time step to enable a 3-D display of the model to be viewed at each time step.
A production well, labeled PROD and belonging to group G1, is to be drilled in cell position (1,1), and a water injection well, INJ belonging to group G2, is to be drilled in cell (5,5). Both wells will have 8 inch diameters, and should be completed in all three layers. They both have pressure gauges at their top perforation (8,000 ft).
Both will be open from the start of the simulation, enabling production of 10,000 stb/day of liquid (oil + water) from the system, and pressure support provided by injection of 11,000 stb/day of water. The simulation should run for 2,000 days, outputting data every 200 days.
A number of keywords in the SCHEDULE section will be able to read in data that the user may wish to default or not supply all. This can be done by using the “*”
character, with the number of values to be defaulted or ignored on the left, and the space to the right left blank. Thus “1* “ ignores one value, “2* “ ignores the next two values, etc. For example, in the COMPDAT keyword, we may wish to specify values for items 1 to 6, and item 9 (which is the wellbore diameter), but items 7 and 8 should remain unspecified. This may be achieved as follows:
Completion interval
Well Location Interval Status Well
name I J K1 K2 O or S ID
Item number
1 2 3 4 5 6 7 8 9
PROD 1 1 1 3 OPEN 2* 0.6667 / /
COMPDAT
The keywords to be used are:
SCHEDULE Section header
RPTRST Request output of cell pressures and saturations at all time steps (t > 0)
WELSPECS Define location of wellhead and pressure gauge COMPDAT Define completion intervals and wellbore diameter WCONPROD Production control
WCONINJ Injection control
TSTEP Time step sizes (for output of calculated data) END End of input data file
These keywords should appear as the last section of the data file as shown in Figure 10. Although not the case in this simple example, this section will typically be the longest, containing flow rates for each well on a monthly basis for the history of the
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Reservoir Simulation Model Set-Up
data are output. The simulator will try to use these time step sizes as numerical time step also, but if the calculations do not converge, it will automatically cut the numerical time step sizes.
SCHEDULE
Output to Restart file for t > 0 (.UNRST) Restart file Graphics every step only RPTRST
BASIC=2 NORST=1 /