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1
Use of Eductor for Lifting
Water
By David Simpson
Overview
• Eductor theory
• Case studies
• Equipment configuration
2
Eductor Theory
• From the family of thermocompressors that includes Air Ejectors,
Evacuators, Sand Blasters, Jet Pumps, and Eductors
• High pressure gas entrains and compresses suction gas and the
combined stream is left at an intermediate pressure
• Compression rations 1.3-2.0 are possible, limited by:
– Power gas pressure
– Suction pressure
– Discharge pressure
Eductor Example
• P
• Gas is Methane
• m
power
• m
suct
• P
• T
• P
• R=1.5
• Find
atm=12 psia°=600 lb/hr°=300 lb/hrpwr=100 psigpwr=80°Fdisc=21 psig
– P
q
suction, qpower,suction
day
MCF
ft
lbm
hr
lbm
q
ft
lbm
psia
psi psig
R
P
P
d
MCF
ft
lbm
hr
lbm m
q
ft
lbm psia
Z T
P MW
suct
suct
disch
suction
pwr
pwr
power
168
1000 * 98 . * 520 * 73 . 14
24 * 98 . * 520 * 22
064 . 0
300
064 . 0
98 . * ) 60 460 ( * 73 . 10
22 * 16
22
5 . 1
) 12 21 (
333
1000
24
97 . 0 * 540 * 73 . 14
98 . 0 * 520 * 112
319 . 0
600
?
319 . 0
97 . * ) 80 460 ( * 73 . 10
112 * ) 16 (
* * 73 . 10
*
?
3
3
3 pwr
3
= ÷
ø
ö
çè
æ =
=
+
=
=
+
= =
= ÷
ø
ö
çè
æ = =
=
+
= =
r
&
At 10 psig, 60
Move 0.75 bbl/day up 3,000 ft of
2-3/8 tubing
3
°F, and 168 MCF/d you can
Eductor Theory
• Small amount of hp
– 16 hp for power gas
– 7.4 hp used in eductor
–
e=46%
• Slow to react (can take
2-3 weeks or longer to
stabilize water level)
• Pretty effective in
maintenance mode
Eductor Rules of Thumb
• For an eductor with gas as the power fluid:
– Exhaust pressure should be less than ½ power-gas pressure (in
absolute terms)
– Exhaust pressure should be less than twice suction pressure
– Mass flow rate of power gas will be about twice suction mass flow
rate.
• With liquid as the power fluid:
– You don’t get to critical flow so the exhaust pressure can be higher
– More “compression ratios” are possible (i.e., the ratio of the
exhaust over the suction can be more than 2)
• If the power gas is a mixture of gas and liquid, calculate
the density and the mass flow rate carefully
4
Case Studies
Hendrickson /B/ 1
-
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
5,000
-365
-274
-183
-91
0
91
182
273
365
456
547
638
729
821
912
1,003
1,094
1,185
1,277
1,368
Base rate
Actual
75% decline
Installed
Compressor
31% decline
Case Studies
So Ute Tribal /H/ 2
-
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
4,500
-365
-274
-183
-91
0
91
182
273
365
456
547
638
729
821
912
1,003
1,094
1,185
1,277
Base rate
Actual
Raised casing pressure from 10 psig to 24 psig.
Ratios went from 0.9 to 1.3
33% decline
22% decline
5
Equipment Configuration
Equipment Configuration
• Must have
– At least two lines from wellhead to separator
– Check valve on tubing line between eductor and separator
– Compressor with at least 50 psig discharge and 20 Hp extra
– Patience (it can take 2-3 weeks before you see results)
• Good to have
– Block valve between eductor and check with blow down on check
side of block
– Two inlet nozzles on separator (without this, you must be very
careful how you bring the two lines together)
6
Screening Criteria for Other
Applications
• Need a source of gas pressure at least twice (in psia) the
exhaust pressure.
• Need an application where 1.5-2.0 ratios does some good.
• Example:
– You have a well with 500 psig upstream of a choke, line pressure
is 150 psig
– A nearby well would flow better at 75 psig line pressure
– Can you use the energy you’re loosing across the choke to drive an
eductor to pull on the nearby well?
OK psig psig
+
- - > = -
150 244 12
2
12 500
OK ratios
+
+
- - =
86 . 1
12 75
12 150
Possibly, need to check rates
Other Possibilities
500 psig 150 psig
80 psig
2 0 p s ig
6 0 p s ig
2 2 0 p s ig 1 0 0 p s ig
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