Fracture separation doesn't affect results for certain inputs

[softwareengineerprogrammer]

Per user feedback

Example input (note typo of "Fracture Seperation" as discussed below):

# ***Subsurface technical parameters***
# *************************************
Reservoir Model,1,                        			---Multiple Fractures reservoir model
Reservoir Depth,3,                     				---[km]
Number of Segments,1,                  				---[-]
Gradient 1,100,                          			---[deg.C/km]
Maximum Temperature,350,                  			---[deg.C]
Number of Production Wells,1,            			---[-]
Number of Injection Wells,1,            			---[-]
Production Well Diameter,7,		     			---[inch]
Injection Well Diameter,7,					---[inch]
Ramey Production Wellbore Model,True,
Production Wellbore Temperature Drop,.5,			---[deg.C]
Injection Wellbore Temperature Gain,0,   			---[deg.C]
Production Flow Rate per Well,60,       			---[kg/s]
Fracture Shape,2,                       			---[-] Should be 1 2 3 or 4. See manual for details
Fracture Height,1000, 						---[m]
Fracture Seperation,80, 					---[m]
Reservoir Volume Option,1,              			---[-] Should be 1 2 3 or 4. See manual for details
Number of Fractures,10,		  				---[-]
Reservoir Volume,1000000000,		 			---[m^3]
Water Loss Fraction,.02,					---[-]
Productivity Index,5,						---[kg/s/bar]
Injectivity Index,5,						---[kg/s/bar]
Injection Temperature,50,		 			---[deg.C]
Maximum Drawdown,1,			  			---[-] no redrilling considered
Reservoir Heat Capacity,1185,		  			---[J/kg/K]
Reservoir Density,2460,			  			---[kg/m^3]
Reservoir Thermal Conductivity,3.1,	  			---[W/m/K]

# ***SURFACE TECHNICAL PARAMETERS***
# **********************************
End-Use Option,1,			  			---[-] Electricity
Power Plant Type,1,			  			---[-] Supercritical ORC
Circulation Pump Efficiency,.8,	  				---[-] between .1 and 1
Utilization Factor,.9,			  			---[-] between .1 and 1
Surface Temperature,20,		  				---[deg.C]
Ambient Temperature,15,		 				---[deg.C]

# ***FINANCIAL PARAMETERS***
# **************************
Plant Lifetime,30,			  			---[years]
Economic Model,2,			  			---[-] Fixed Charge Rate Model
Fixed Charge Rate,.05,			 			---[-] between 0 and 1
Inflation Rate During Construction,0,   			---[-]

# ***CAPITAL AND O&M COST PARAMETERS***
# *************************************
Well Drilling and Completion Capital Cost Adjustment Factor,1,	---[-] Use built-in correlations
Well Drilling Cost Correlation,1,				---[-] Use built-in correlations
Reservoir Stimulation Capital Cost Adjustment Factor,1,		---[-] Use built-in correlations
Surface Plant Capital Cost Adjustment Factor,1,			---[-] Use built-in correlations
Field Gathering System Capital Cost Adjustment Factor,1,	---[-] Use built-in correlations
Exploration Capital Cost Adjustment Factor,1,			---[-] Use built-in correlations
Wellfield O&M Cost Adjustment Factor,1,				---[-] Use built-in correlations
Surface Plant O&M Cost Adjustment Factor,1,			---[-] Use built-in correlations
Water Cost Adjustment Factor,1,					---[-] Use built-in correlations


# ***Simulation Parameters***
# ***************************

Print Output to Console,1,		  			---[-] Should be 0 (don't print results) or 1 (print results)
Time steps per year,6,		  				---[1/year]

[softwareengineerprogrammer]

Two findings after looking now:

1. The user-provided input misspelled the parameter name as "Fracture Seperation" - it should be "Fracture Separation".
2. I ran a sensitivity test on the user-provided input with the corrected parameter name which demonstrates that results are sensitive for values ≤ 12:

Converting this to a discussion since it's unclear whether there's an actual issue here - at this point I am presuming it is expected behavior of the reservoir model in some form.

[softwareengineerprogrammer]

I investigated further by increasing the number of injection wells to 5 and comparing electricity production across fracture separations 5-85. The results are sensitive to all fracture separation values. Thus, I believe the lack of sensitivity observed with 1 injection well is expected behavior in the form of a constraint on max production per injection well.

Sample input; result:

# ***Subsurface technical parameters***
# *************************************
Reservoir Model, 1
Reservoir Depth, 3
Number of Segments, 1
Gradient 1, 100
Maximum Temperature, 350
Number of Production Wells, 5
Number of Injection Wells, 1
Production Well Diameter, 7
Injection Well Diameter, 7
Ramey Production Wellbore Model, True
Production Wellbore Temperature Drop, .5
Injection Wellbore Temperature Gain, 0
Production Flow Rate per Well, 60
Fracture Shape, 2
Fracture Height, 1000
Fracture Separation, 80
Reservoir Volume Option, 1
Number of Fractures, 10
Reservoir Volume, 1000000000
Water Loss Fraction, .02
Productivity Index, 5
Injectivity Index, 5
Injection Temperature, 50
Maximum Drawdown, 1
Reservoir Heat Capacity, 1185
Reservoir Density, 2460
Reservoir Thermal Conductivity, 3.1

# ***SURFACE TECHNICAL PARAMETERS***
# **********************************
End-Use Option, 1
Power Plant Type, 1
Circulation Pump Efficiency, .8
Utilization Factor, .9
Surface Temperature, 20
Ambient Temperature, 15

# ***FINANCIAL PARAMETERS***
# **************************
Plant Lifetime, 30
Economic Model, 2
Fixed Charge Rate, .05
Inflation Rate During Construction, 0

# ***CAPITAL AND O&M COST PARAMETERS***
# *************************************
Well Drilling and Completion Capital Cost Adjustment Factor, 1
Well Drilling Cost Correlation, 1
Reservoir Stimulation Capital Cost Adjustment Factor, 1
Surface Plant Capital Cost Adjustment Factor, 1
Field Gathering System Capital Cost Adjustment Factor, 1
Exploration Capital Cost Adjustment Factor, 1
Wellfield O&M Cost Adjustment Factor, 1
Surface Plant O&M Cost Adjustment Factor, 1
Water Cost Adjustment Factor, 1


# ***Simulation Parameters***
# ***************************

Print Output to Console, 1
Time steps per year, 6