EXAMPLE 1
SIZING FOR WATER SOURCE WELL
Step # 1 Collect and analyze well, production, fluid and power supply data.
A Well data
Total Depth: 6500'
Perforations: 5950 - 5980'
Casing size: 7", 20 #/ft
Tubing: 3.5" 8 rd. EUE
B Production data
Static Fluid Level: 1000' from surface
Producing Level 1300'
Current Production Rate: 1000 B/D 100% Salt water
BHT: 160 Deg. F
Req. Discharge Pressure: 50 psi
C Fluid Data:
Specific Gravity, water: 1.05
D Power System
Primary Volytage: 24500 V
E Required Production Rate: 4000 B/D
Step # 2 Analyze the above data to detrmine well's productivity.
Remember the following simple equations
Q B/D
PI =
(Ps - Pwf) psi
P = Depth (ft) X Gradiant (psi/ft)
Pwf= (Perfs Depth - DFL) X Avg. Gradiant
Ps= (Perfs Depth - SFL) X Avg. Gradiant
Gradiant Sp Gr X Water Gradiant
Solve for our Example
Gradiant= 1.05 X 0.433 0.4547
Ps= (5950 - 1000) X 0.433 2250.5 psi @ top of perforation
Pwf= (5950-1300) X 0.433*1.05 2114.1 psi @ top of perforation
1000
PI = 7.3 psi/ B/D
2143.35 - 2013.45
Pwf= Ps - Q/PI 1702 Psi @ 4000 B/D
DFL = Perfs Depth - Pwf/Gradiant
DFL = 5950 - 1702/0.4515 2180 ft, Net Lift at 4000 B/D
Max Q= PI X Ps 16425 B/D @ zero flowing pressure
In a water well it is recommended to set the pump suction between 300 - 500' be
In this example let us set the ESP at 2600', 400' below the anticipated DFL
Step # 3 Caculate Total Dynamic Head (TDH)
TDH= Net Lift + Friction Loss + Required Discharge Pressure
RDP= Pressure/gradiant 110.0 ft
FL= Friction at 4000 B/D in 3.5 tbg per 1000' X pump depth / 1000
47 X 2600/1000 122.2 ft
TDH= 2180 + 110 + 122 2412 ft
Step # 4 Select from the pump curves the pump type which will operate mos
From Reda Catalog, GN4000 will have the best efficiency and it ca
between 3200 - 4500 B/D
Step # 5 Calculate number of stages required.
At 4000 B/D the head capacity of the GN4000 pump is 34 ft per sta
No. of Stgs= TDH/Ft per stage
No. of Stgs= 2412/34 70.9 Stages
From the Catalog, GN4000, 73 stages Housing # 110 is selected
Step # 6 Detrmine motor horsepower required and select motor voltage and
HP= No. of stages X BHP required per stage X avg Sp. Gr
HP= 73 X 1.5 X 1.05 114.98 HP
From the Catalog, 540 series motors the availabe motor is 120 HP
Volts Amps
1105 69.5
1350 58.5
2270 32.5
To select the motor, we have to look ahead to step # 7, cable selec
switchboard selection, to determine the most efficient motor voltage
the best installation.
A If the 1105V, 69.5A motor is selected, we would be able to utilize a
to the high current we must select cable with conductor # 2
Cable Cost 12000 $
SB Cost 6000 $
Total Cost 18000 $
B If the 1350V, 58.5A motor is selected, we would be able to utilize a
to the reduced current we can select cable with conductor # 4
Cable Cost 9000 $
SB Cost 6000 $
Total Cost 15000 $
C If the 2270V, 32.5A motor is selected, we would be able to utilize #
be forced to use a 2400V SB
Cable Cost 7000 $
SB Cost 10000 $
Total Cost 17000 $
It is obvious that the 120 HP mptor having 1350V and 58.5A motor
Step # 7 Select Cable
Round Cable # 4 is selected as per step # 6.
Step # 8 Determine the required Surface voltage
Surface V. = (Motor Voltage + Cable Loss) X Transformer Loss factor
Cable # 4 loss at 58.5 Amp at 77 F, 26 V/1000 ft, this loss to be cor
Cable # 4 loss at 58.5 Amp at 160 F, 26X1.19, 31V/1000 ft at the B
Transformer Loss is 2.5%, the factor is 1.025
Surface V. = (1350 + 31X2700/1000) X 1.025 1470 Volt
Step # 9 Calculate the KVA
KVA= (SV X Amps X 1.73)/1000 150
1
OURCE WELL
n, fluid and power supply data.
B/D @ zero flowing pressure
p suction between 300 - 500' below the DFL
ump type which will operate most efficiently.
have the best efficiency and it can operate
he GN4000 pump is 34 ft per stage
ges Housing # 110 is selected
ed and select motor voltage and imperage
rs the availabe motor is 120 HP with the folowing:
k ahead to step # 7, cable selection and step # 8,
e the most efficient motor voltage and amperage for
ed, we would be able to utilize a 1500V S. B. and due
ed, we would be able to utilize a 1500V S. B. and due
ed, we would be able to utilize # 6 cable but we would
having 1350V and 58.5A motor should be selected.
, 26 V/1000 ft, this loss to be corrected to the BHT
F, 26X1.19, 31V/1000 ft at the BHT 160 F
