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Liquid LoadingDave Barry
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Liquid Loading
All gas wells, at some time during there producing life, willexperience liquid loading problems
Once Flowrate drops below a certain rate, the well will begin toload up
The amount of liquid produced does influence how quickly thesubsequent loading up process takes
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Critical Velocity
Gas velocity (Flowrate) in the tubing has drops below the minimum
required to move liquids up and out of the wellbore.
Liquids are settle in the bottom of the well tubing.
Gas flows in heads (slug flow) or bubble flow (gas bubbles through
liquids).
Loads up during natural flow.
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Typical Production Decline Curve
WellP
roduction
Typical Gas Well Production Decline
Time
NormalDecline
Onset Of Liquid Loading
Deviation
Plunger Installed
CumulativeProductionIncrease
Forecasted Decline with no Intervention
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Popular Remedies
Subsurface
Velocity Tubing Stings (Requires
Workover)
Pumping Unit (Expensive to Operate)
Electric Submersible Pumps (Expensiveto install, expensive to work on, expensive to operate)
Plunger Lift (Lowest Cost to Install, easy tooperate, low recurring costs)
Surface
Venting (Environmental Issues)
Intermitting (Good 1st Step, but limitedtime usage)
Soaping (Messy and Expensive)
Chemical Injection (Expensive)
Gas Lift (Works, but have to buy back gasto inject)
Compression (Maintenance &Expensive)
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Comparing Remedies
Criteria
Lowest flowing bottom hole pressure desired
Equals Lowest casing pressure
Mechanical limitations
Limit Choices
Cost Analysis
Choice has to make economic sense
Have to make more money, not just more oil/gas
Operator Capabil ities
Operators can do what they are trained to do Must learn required skills
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What is Plunger Lift
Technique used to optimize gas production.
Steel plunger is inserted into the production tubing.
Well shut-in causes plunger to fall allowing fluid to collect above
plunger.
Different techniques are used to decide how long to shut in and flowthe well.
Downhole pressure is used to lift the plunger and fluid to surface.
Goal is to increase gas production by keeping liquid off formation.
Generally speaking these wells dont have enough constant
downhole pressure to free flow into a gathering system.
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Candidate Selection: Is Plunger Lift Appropriate?
Does the Gas to Liquid Ratio meet the minimum
requirements? 400 scf per bbl per 1000' of lift depth
Does the shut in pressures meet minimum
requirements? Load Ratio
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GasGas
FlowFlow
MistMist SlugSlug BubbleBubbleAnnularAnnular
Gas Well Life Cycle: Plunger Lift
Decreasing Gas VelocityDecreasing Gas Velocity
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Typical Plunger Lift Wellhead Setup
Lubricator / Catcher
Collar Stop / Springs
Plunger
Controller
Tubing Xdcr
Casing Xdcr
Arrival Switch
A typical system consists of:
Collar Stop & Spring
Plunger
Lubricator / Catcher
Controller
Master Valve
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Typical Wellhead Hardware Detail
Tubing Transducer
Arrival Switch
Casing Transducer
Latching Solenoid
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Plunger Force Balance
101) Stored casing pressure freely acting on the
cross-section of the plunger2) Stored reservoir pressure acting on the cross-
section of the plunger, based on inf lowperformance
3) Weight of the liquid above the plunger4) Weight of the plunger5) Friction of the fluid with the tubing6) Friction of the plunger with the tubing7) Gas friction in the tubing8) Gas slippage upward past the plunger9) Liquid slippage downward past the plunger10) Surface pressure (line pressure and
restrictions) acting against the plunger travel4
3
7
5
8
6 1
9
2
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Plunger Products
Pa d P l u n g e r s h a v e
i n t e r l o c k i n g s t a i n l e s s s t e e l
p a d s t o c r e a t e a s u p e r i o r
s e a l . Th e s p r i n g - l o a d e d
p a d s a r e a lw a y s e x p a n d e d
y e t h a v e e n o u g h f l e x t o
a l l o w t h e p l u n g e r t o f a l l
t h r o u g h m i n o r t u b i n g
a n o m a l i e s .
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Plunger Products
Fi b e r p l u n g e r s Fi b e r p l u n g e r s ,, w i t h i t s w i t h i t s n y l o n s e a l i n g e l e m e n t , i s n y l o n s e a l i n g e l e m e n t , i s
u s ed i n w e a k e r w e l l s a n d u s ed i n w e ak e r w e l l s a n d s a n d p r o d u c i n g w e l l s . N o s a n d p r o d u c i n g w e l l s . N o
m o v i n g p a r t s m a k e s i t t h e m o v i n g p a r t s m a k e s i t t h e
i d e a l p l u n g e r w h e r e s a n d i s i d e a l p l u n g e r w h e r e s a n d i s
p r e s e n t .p r e s e n t .
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Down Hole Products
D o w n h o l e sp r i n g s D o w n h o l e sp r i n g s
a n d s t o p s a r e a n d s t o p s a r e
e n g i n e e r e d a n d e n g i n e e r e d a n d
m a n u f a c t u r e d in a m a n u f a c t u r e d i n a v a r i e t y o f v a r i e t y o f
c o n f i g u r a t i o n s c o n f i g u r a t i o n s ..
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Inflow Performance Analysis for Plunger Lift
Example of using inflow performance analysis to estimate plunger liftperformance. Chart shows production increase resulting fromreducing liquid hydrostatic pressure with a plunger lift system.
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Inflow Performance Relationship
Optimum Performance Cycle Frequency equals smallest liquid loads Smallest liquid load equals lowest BHP requirements Lowest operating BHP equals best inflow performace
Smallest
LiquidLoads
MostCycles
Lowest
BHPRequirements
Best Inflow
Performance$$$$$$
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Plunger Lift vs. Gas Production Theory
The producing tendency of plunger lift is directly opposed to that of the well.
Plunger lift requires an increase in casing pressure for increased production.
The well requires a decrease in casing pressure for increased production.
The compromise that always yields the greatest production is found whencycling the plunger at the maximum frequency possible without killing thewell.
J im Hacksma (Consultant)
1972, Users Guide to Plunger Lift Performance
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Plunger Lift States
Closing Valve
Closing Valve
Valve Closed
(Plunger on Bottom)
Valve Open
Flowing
Plunger Arrived
Arriving
Falling
Waiting
Falling
Valve Closed
Waiting
Valve Open
Plunger Arrived
Arriving
Flowing
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Valve Closed (State 2)
1) Timer
2) Tubing - LineCasing - Tubing / Casing - Line
3) Casing - LineCasing Tubing / Fluid Gradient
4) Casing - Line & Tubing - Line
5) Casing - Tubing
6) Casing Tubing & Tubing - Line
7) Load Ratio
8) Tubing Pressure
9) Casing Pressure
10) Static Pressure
11) Slug Size
12) Optional Input (2)
l i i ( )
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Plunger Arriving (State 3)
Arrival Times
Minimum
Maximum
Slow
Fast
Close A Valve or Open B Valve
Tune for faster next cycle
Dont tune(ascension velocity is correct)
Tune for slower next cycle
Dont tune(plunger may not have reached bottom)
Recommended Ascension Velocity:750 1,000 ft/min
Aft fl (St t 6)
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Afterflow (State 6)
1) Timer
2) Turner
3) Load Ratio
4) Differential Pressure
5) Flowrate
6) Tubing - Line
7) Casing - Tubing
8) Tubing Pressure
9) Casing Pressure
10) Static Pressure
11) Slug Size
12) Optional Input (2)
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Foaming
Reduces surface tension
Reduce the density of the liquid droplets
Therefore reduces the required Critical Velocity
Works best on wells with >= 50% Water
Advantages
1. Simple & inexpensive option for low ratewells. Proportional to liquid water rate.
2. No downhole equipment required.
Works best with a capillary tube.3. Gas velocities of 100 to 1,000 fpm.
Disadvantages
1. Foam carryover or liquid emulsion problems.
2. Effectiveness depends on type amount of wellfluids. Wells producing >50% condensate
may not foam.
Ch i l I j ti
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Chemical Injection
Gas Flow
Casing
Tubing
Pneumatic Valve
G4XRCPulse Meter
Chemical Injection Tank
Chemical Injection Pump
Ch i l I j ti
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Chemical Injection
Lowers the Critical Velocity needed to lift fluids to thesurface
Precise Injection of Chemical
Increased Revenues
Alarm Monitoring Controls either Motor Driven Pump or Piston Pump
S Sti k L h
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Soap Stick Launcher
S Sti k L h C t l
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Soap Stick Launcher Control
Control Launcher based on Flowrate or Critical Rate
Monitors Flow to determine if another Stick is necessary
Tracks Sticks remaining in Launcher, alarms when low
Set # of Sticks to drop before shut-in Reset on increase Flowrate
What is Automation?
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What is Automation?
What Does Automation Mean for YOU.
Spend less time doing tedious manual steps to accomplish simple tasks.
Become more efficient by learning to use the system or systems to work for
you, not you working the systems.
Let the systems help you become proactive to prevent issues, rather thanreactive when an issue happens.
Let the systems make your job easier.
Q ti
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Questions
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