Guidelines & Recommended Practices
Selection of Artificial Lift Systems
for Deliquifying Gas Wells
2.2a Artificial Lift Selection Methods
This presents information that may assist with the selection of artificial lift for gas
wells
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Advantages / Disadvantages
Rules of thumb
Depth/ Rate capabilities
Power consumption
1. Selection of Deliquification Method
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There is no generally accepted method for selecting the “best” artificial lift method for gas well deliquification.
There are many factors to consider.
Consideration of some factors can lead to improved selection.
Some (not all) important factors are considered here.
2. Some Popular Artificial Lift Methods
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Electrical submersible pumping
Progressing cavity pumping
Beam pumping
Hydraulic pumping
Gas lift
Velocity strings
Compression systems
Plungers
Foaming
Injection systems
3. Artificial Lift Selection Process
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Make a “Rough Cut” choice with Artificial Lift Screening Criteria
Review Feasibility / Functionality of Artificial Lift Methods
Evaluate Cost --- CAPEX, OPEX
Consider Availability, Use of Reservoir Energy
Consider Availability of Required Infrastructure
Consider Availability of Required Operator Training
4. Approximate Capital Costs (CAPEX)
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Indication If Electrical Energy is Needed
Is an Injection Line is Needed
Is energy is Needed from the Reservoir
The Degree of Involvement Needed by the Operators
Selection of Artificial Lift Systems for Deliquifying Gas Wells
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5. Critical Gas Flow Rate as a Function of Tubing Size and Wellhead Pressure
Selection of Artificial Lift Systems for Deliquifying Gas Wells
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6. Operating Costs:
–
Power efficiency may be defined as: the fraction of the power used to lift liquids divided
by the total power supplied.
–
Assume a 20 hp load for all methods (when applicable), 4000’ lift, 20 bpd, specific gravity =
1.0, and efficiency as defined below. Assume 200 barrels per day for high rate lift methods.
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Efficiency =  = .00000736 (Lift, ft) (BPD) () / (kW/.746)
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kW = .00000736 x 20 x 4000 x 1.0 x 0.746/  = 0.4356/
7. Assume electrical costs of $0.08/ (kW-hr)
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$/year = 0.4356 x 0.08 x 365 x 24 /  = 305 / 
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$/year  300/ for low rate case of 20 bpd
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$/year  3000/ for high rate case of 200 bpd
Method:
ESP
PCP
Beam
Hydraulic jet
Gas lift
Velocity strings
Compression
Plungers
Foaming
Injection systems

40
60
50
20
20
80
-
Selection of Artificial Lift Systems for Deliquifying Gas Wells
8. Ranges of Efficiency for Different Artificial Lift Methods
By Weatherford (above)
9. Pros and Cons for Different Artificial Lift Methods
Table of Lift Pros/Cons
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
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10. Lift Rate Screening Chart for High Rate Wells (from Weatherford)
Selection of Artificial Lift Systems for Deliquifying Gas Wells
11. Lift Rate Screening Chart for Low Rate Wells (from Weatherford)
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
12. Possible Pressure Drawdown Capabilities
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
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13. Examples of Selection Trees or Flow Charts for Selection of Lift Method to
Dewater
Monthly Production Data
Generate Velocity Profiles
no
Does Available Data Indicate Liquid Loading
yes
Run Pressure Gradient Survey
no
Has a Pressure Gradient survey Been Run?
yes
Open All Cotton Valley Pay
no
Is All Cotton Valley Pay Open?
yes
Install Soap Injection
yes
Is Soap Injection Feasible?
no
Install Small Diameter Tubing
yes
Well Workover Scheduled?
no
Lower the Flowing Tubing Pressure
yes
Can the Flowing Tubing Pressure be
Lowered?
no
Implement a Pseudo-Gas Lift System
yes
Can a Pseudo-Gas Lift System be
Implemented Without Killing the Well
no
Install a Plunger Lift
yes
Is Plunger Lift Feasible?
no
Install Gas Lift
yes
Is Gas Lift practical?
no
Install Beam Lift
yes
Is Beam Lift Practical?
no
Produce to Depletion
Plug & Abandon
Selection of Artificial Lift Systems for Deliquifying Gas Wells
Selection Chart: For discussion
Check for loading:
•Critical velocity or rate?
•Falls off decline curve and stays
there?
•Initiation of slugging?
•Difference between tbg-csg pressure
increases with time?
•Other?
Team meeting:
•Establish stable rate (swab?)
•Determine gas rate, condensate rate,
water rate
•Some operators check flowing
pressure survey
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
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Screen AL method considering conditions
Sand?
Hi-Rate?
Hi Surf P?
Lo Rate?
PCP,
Gaslift,
ESP,
Compress,
1.
Swab,
Gaslift,
Pump,
2.
Stop Clock,
Velocity
String,
Other?
3.
Plunger,
4.
Gaslift,
5.
Foam,
6.
Pumping
methods
7.
Other?
Velocity
String,
Foam ,
some
pumping
methods
Beam,
Other?
Preferred? For discussion:
1. Plunger (conventional, two piece, free cycle,
other? if feasible)
2. Foam (soap sticks(shallow), batch treat with no
packer, Cap tube injection with packer present if
water and no high condensate.
3. Gaslift
4. Pumping methods (Beam, ESP, Diaphragm, PCP,
Hydraulic, other?)
5. Consider special devices: Collar inserts, Vortex,
Goal, other?
6. Inject water if feasible
14. Example Problem to Show Selection Process for Dewatering Technique: Capacity and Economics Selection
Base Data:
Depth=9800
Tubulars for Cases (1) &(2)
2 3/8 tubing
4 1/2 casing
(1.995"id)
(4.00" ID)
BHT=320F
GG=.6
WHT=150F
WG=1.0
WHP=300 psia
API=35
WC(fraction)=5.
Pr=1111 psia
n=1.0
Tubulars for Cases (3) &(4)
2 7/8 tubing
5 1/2 casing
(2.441"id)
(5.044" ID)
Q=C(Pr^2Pwf^2)^n
C given below
Selection of Artificial Lift Systems for Deliquifying Gas Wells
Roughness=.0018
Inject gaslift at
EOT
Plunger Specific Data>
Max
Pcsg=900psi
Min Pcsg=150psi
C (Mscfd/psi^2n) =
bbl/mmscf=
(1 )Low Gas ,
Low Liquids
0.0003
50
(2) Low Gas,
High Liquids
0.0003
300
Mscf/D Max=
BPD, Max=
Mscf/D Max=
BPD, Max=
Mscf/D Max=
BPD, Max=
Mscf/D Max=
BPD, Max=
Mscf/D Max=
BPD, Max=
Gaslift
determine
determine
Pumps
determine
determine
Cap String
determine
determine
Plunger
determine
determine
Smaller Tubing
determine
determine
For pumps assume liquid level
at EOT
Gaslift
determine
determine
Pumps
determine
determine
Cap String
determine
determine
Plunger
determine
determine
Smaller Tubing
determine
determine
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Cap String: Use
inputs for Surfactants
(3) High Gas, Low
Liquids
0.0006
50
Gaslift
determine
determine
Pumps
determine
determine
Cap String
determine
determine
Plunger
determine
determine
Smaller Tubing
determine
determine
(4) High Gas,
High Liquids
0.0006
300
Gaslift
determine
determine
Pumps
determine
determine
Cap String
determine
determine
Plunger
determine
determine
Smaller Tubing
determine
determine
The results below are obtained from SNAP for gas-lift; SNAP and Prodop for Cap Stringws; PDA for
plunger lift; and SNAP for pumps.
 SNAP is available from Ryder Scott Company (http://www.ryderscott.com)
 Prodop is available from Weatherford
(http://www.weatherford.com/Products/Production/ProductionOptimization/
 PDA is available from PL Tech, LLC (http://www.pltechllc.com/)
It is assumed that pumps (beam or electrical submersible pump) could be used to pull the fluid level down
to above the perforations. Costs for beam are used here.
Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (1) Gaslift
Case(2) Gaslift
Case(3) Gaslift
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case(4) Gaslift
Case (1) & (2) Pumps
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (3) & (4) Pumps
Case (1) Cap String
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (2) Cap String
Case (3) Cap String
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (4) Cap String
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (1) Plunger
Case (2) Plunger
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (3) Plunger
Case (4) Plunger
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
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RESULTS FROM
ABOVE ANALYSES:
Mscf/D & BPD
GASLIFT GAS
288
245
583
490
GASLIFT LIQUIDS
14
332
74
332
29
664
149
664
17
307
100
284
33
617
199
573
PLUNGER GAS
15
240
85
N0
31
583
172
NO
PLUNGER LIQUID
12
NO
29
NO
PUMPS GAS
PUMPS LIQUID
CAP STRING GAS
CAP STRING LIQUID
Below are economic calculations for a 5 year period with constant production. No failures are assumed. This is for illustration to show how a longer term more exact calculation could be used given this type of data.
See installation and operating costs tables at end of document.
Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (1) Gaslift 283 MscfD and 7 bpd condensate
Initial Cost
Operating Cost
-$28,000.00
-$192,000.00
Gas Revenue
$2,065,900.00
BPD revenue
$1,277,500.00
Total Revenue 5 yr
$3,123,400.00
Case (2) Gaslift 245 MscfD and 37 bpd condensate
Initial Cost
Operating Cost
-$28,000.00
-$192,000.00
Gas Revenue
$1,788,500.00
BPD revenue
$6,752,500.00
Total Revenue 5 yr
$8,321,000.00
Case (3) Gaslift 583 MscfD and 14.5 bpd condensate
Initial Cost
Operating Cost
-$28,000.00
-$192,000.00
Gas Revenue
$4,255,900.00
BPD revenue
$2,646,250.00
Total Revenue 5 yr
$6,682,150.00
Case (4) Gaslift 490 MscfD and 74.5 bpd condensate
Initial Cost
Operating Cost
-$28,000.00
-$192,000.00
Gas Revenue
$3,577,000.00
BPD revenue
$13,596,250.00
Total Revenue 5 yr
$16,953,250.00
Case (1) Pumps 332 MscfD and 8.5 bpd condensate
Initial Cost
Operating Cost
-$88,000.00
-$54,000.00
Gas Revenue
$2,423,600.00
BPD revenue
$1,551,250.00
Total Revenue 5 yr
$3,832,850.00
Case (2) Pumps 332 MscfD and 50 bpd condensate
Initial Cost
-$88,000.00
Operating Cost
-$54,000.00
Gas Revenue
$2,423,600.00
BPD revenue
$9,125,000.00
Total Revenue 5 yr
$11,406,600.00
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
Case (3) Pumps 664 MscfD and16.5 bpd condensate
Initial Cost
Operating Cost
-$88,000.00
-$54,000.00
Gas Revenue
$4,847,200.00
BPD revenue
$6,022,500.00
Total Revenue 5 yr
$10,727,700.00
Case (4) Pumps 664 MscfD and 99.5 bpd condensate
Initial Cost
-$88,000.00
Operating Cost
-$54,000.00
Gas Revenue
$4,847,200.00
BPD revenue
$18,158,750.00
Total Revenue 5 yr
$22,863,950.00
Case (1) Cap String 307 MscfD and 7.5 bpd condensate
Initial Cost
-$19,000.00
Operating Cost
-$24,000.00
Gas Revenue
$2,971,100.00
BPD revenue
$1,368,750.00
Total Revenue 5 yr
$4,296,850.00
Case (2) Cap String 284 MscfD and 42.5 bpd condensate
Initial Cost
-$19,000.00
Operating Cost
-$24,000.00
Gas Revenue
$2,073,200.00
BPD revenue
$7,756,250.00
Total Revenue 5 yr
$9,786,450.00
Case (3) Cap String 617 MscfD and 15.5 bpd condensate
Initial Cost
Operating Cost
-$19,000.00
-$24,000.00
Gas Revenue
$4,504,100.00
BPD revenue
$2,828,750.00
Total Revenue 5 yr
$7,289,850.00
Case (4) Cap String 573 MscfD and 86 bpd condensate
Initial Cost
-$19,000.00
Operating Cost
-$24,000.00
Gas Revenue
$4,182,900.00
BPD revenue
$13,140,000.00
Total Revenue 5 yr
$17,279,900.00
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Selection of Artificial Lift Systems for Deliquifying Gas Wells
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Case (1) Plunger 240 MscfD and 6 bpd condensate
Initial Cost
-$8,000.00
Operating Cost
-$12,000.00
Gas Revenue
$1,752,000.00
BPD revenue
$1,095,000.00
Total Revenue 5 yr
$2,827,000.00
Case (2) Plunger 240 MscfD and 6 bpd condensate
PLUNGER WILL NOT WORK
Case (3) Plunger 583 MscfD and 14.5 bpd condensate
Initial Cost
-$8,000.00
Operating Cost
-$12,000.00
Gas Revenue
$4,255,900.00
BPD revenue
$2,646,250.00
Total Revenue 5 yr
$6,882,150.00
Case (4) Plunger 410 MscfD and 62.5 bpd condensate
PLUNGER WILL NOT WORK
Summary Table
Case
Gaslift
Pumps
Cap String
Plunger
1
$3,123,400.00
$3,832,850.00
$4,296,850.00
$2,827,000.00
2
$8,321,000.00
$11,406,600.00
$9,786,450.00
NO
3
$6,682,150.00
$10,727,700.00
$7,289,850.00
$6,882,150.00
4
$16,953,250.00
$22,863,950.00
$17,279,900.00
NO
The summary for the 5 year revenues above show pumps are the best for all but the low gas, low liquids
case where the lower cost of cap string makes it the best. It is understood that the techniques for predicting some of these cases (especially for the cap string and plunger ) are approximate and the techniques
will improve with time. The concepts should remain intact.
Below are installation and operating costs courtesy Weatherford used for the above calculations. It is understood that these costs could vary widely in different parts of the world. Weatherford gives approximate
costs for somewhat higher liquid rates but for simplicity all costs were used from the below two tables.
Selection of Artificial Lift Systems for Deliquifying Gas Wells
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