Rule-of-Thumb Calculation of Key Events During the Plunger ...alrdc.org/workshops/2008_Spring2008GasWellWorkshop... · S-Curve Is used to Determine the Gaseous Liquid Loaded Column

Gas Well Deliquification WorkshopAdams Mark Hotel, Denver, Colorado

February 25 - 27, 2008

Rule-of-Thumb Calculation of Key Events During the Plunger Lift Cycle

James F. Lea, PLTech LLCO. Lynn Rowlan, Echometer Company

Feb. 25 - 27, 2008 2008 Gas Well Deliquification Workshop Denver, Colorado

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1.1. Plunger Lift Operation CyclePlunger Lift Operation Cycle2.2. Minimum Plunger Lift RequirementsMinimum Plunger Lift Requirements3.3. Load Factor Determines if Plunger will Load Factor Determines if Plunger will

SurfaceSurface4.4. Amount & Height of Liquid in TubingAmount & Height of Liquid in Tubing5.5. Minimum ShutMinimum Shut--in Timein Time6.6. Plunger Rise Velocity and Maximum Plunger Rise Velocity and Maximum

Unloading TimeUnloading Time7.7. Plunger Efficiency and Maximum Plunger Efficiency and Maximum AfterflowAfterflow

TimeTime

IntroductionIntroduction


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[A][A] Valve Opens, Valve Opens, Unloading Unloading BeginsBegins

1.1. Liquid Arrives, Liquid Arrives, Tubing Pres. at Tubing Pres. at Minimum Minimum

2.2. Plunger Plunger Arrives, AfterArrives, After--flow begins flow begins Tubing Tubing Pressure SpikePressure Spike

Cycle for Example WellCycle for Example Well[A][A] 11 22 [B][B] 3 43 4 [C][C]

Casing PressureAcoustic Signal

Tubing Pressure

[B][B] Valve Closes, Valve Closes, ShutShut--in Begins in Begins and Tubing and Tubing Pressure Starts Pressure Starts IncreasingIncreasing

3.3. Plunger hits Plunger hits LiquidLiquid

4.4. Plunger on Plunger on BottomBottom

[C][C] Valve Opens, Valve Opens, Unloading Unloading BeginsBegins

14.13

72.34

68.12

Elapsed Time - Minutes


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Equipment on WellEquipment on Well


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Example Output from RulesExample Output from Rules--ofof--Thumb XLS:Thumb XLS:

Initial Conditions:Initial Conditions:ShutShut--in 68:12in 68:12Unloading 14:13 MinUnloading 14:13 MinAfterAfter--Flow 72:34 MinFlow 72:34 Min

Need to Change:Need to Change:Increase AfterIncrease After--FlowFlowReduce ShutReduce Shut--inin


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Plunger Lift RulePlunger Lift Rule--ofof--Thumb Inputs:Thumb Inputs:


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•• Fraction of gas in SlugFraction of gas in Slug (80% is a good guess) (80% is a good guess) –– Cycle Cycle Analysis screen, the % Liquid is displayed while the Analysis screen, the % Liquid is displayed while the plunger falls plunger falls

•• Fudge FactorFudge Factor: Adjust Shut: Adjust Shut--in Time (>1) in Time (>1) –– 1 means do 1 means do not add any time to the Shutnot add any time to the Shut--in time, portion >1 is the in time, portion >1 is the decimal fraction extra shutdecimal fraction extra shut--in timein time

•• Desired Liquid Production, RateDesired Liquid Production, Rate –– Amount of liquid you Amount of liquid you would like to produce from the plunger lift well would like to produce from the plunger lift well

•• Plunger Liquid Removal Efficiency (per cycle)Plunger Liquid Removal Efficiency (per cycle) –– PcPc--Pt is Pt is liquid load, OR Determine Corrected Height of Gassy liquid load, OR Determine Corrected Height of Gassy Fluid Plunger Hits and divide into current production.Fluid Plunger Hits and divide into current production.

Plunger Lift RulePlunger Lift Rule--ofof--Thumb Inputs:Thumb Inputs:


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1.1. Volume of Liquid in the tubing = Volume of Liquid in the tubing = .00224176 (Pcasing.00224176 (Pcasing--Ptubing) (Tbg ID_^2 )/ SpGr of LiquidPtubing) (Tbg ID_^2 )/ SpGr of Liquid

Where .002241 = Where .002241 = =1/ 0.433 * (3.14 /(4*144)) *(1/5.615)=1/ 0.433 * (3.14 /(4*144)) *(1/5.615)

2.2. Height of Gassy Liquid Height of Gassy Liquid –– ftft=(Pcsg=(Pcsg--Ptubing)/ (.433 * SpGr * (1Ptubing)/ (.433 * SpGr * (1--Gas Fraction))Gas Fraction))

3.3. Fall time through gas during ShutFall time through gas during Shut--in Periodin Period=(depth=(depth--height of gassy fluid) / FPM in gas of plungerheight of gassy fluid) / FPM in gas of plunger

4.4. Fall time through gassy liquid during ShutFall time through gassy liquid during Shut--in Periodin Period= height of gassy fluid / fpm of plunger in gassy fluid= height of gassy fluid / fpm of plunger in gassy fluid

5.5. Total fall time + Minimum ShutTotal fall time + Minimum Shut--in Time in Time = 3+4 above= 3+4 above

Plunger Lift RulePlunger Lift Rule--ofof--Thumb Calculations:Thumb Calculations:


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6.6. Total Fall Time x Fudge Factor Total Fall Time x Fudge Factor –– Time for ShutTime for Shut--in Periodin Period=fall time through gas and liquid x Fudge Factor=fall time through gas and liquid x Fudge Factor

7.7. Min CP Required for Casing Pressure Unload LiquidMin CP Required for Casing Pressure Unload Liquid= highest of 2 x LP or 2(Pc= highest of 2 x LP or 2(Pc--Ptbg) + LPPtbg) + LP

8.8. Minimum Plunger Arrival Time (>=1000 Ft/Min)Minimum Plunger Arrival Time (>=1000 Ft/Min)=depth/1000=depth/1000

9.9. Maximum Plunger Arrival Time (<=500 Ft/Min)Maximum Plunger Arrival Time (<=500 Ft/Min)= depth/500= depth/500

10.10. # Cycles/Day to Remove Desired Liquid # Cycles/Day to Remove Desired Liquid = bpd= bpd--liquid / plunger removal efficiency / bbls in tubingliquid / plunger removal efficiency / bbls in tubing



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11.11. Maximum # Cycles/Day Possible Using Above TimesMaximum # Cycles/Day Possible Using Above Times=24 * 60 / ( total fall time x FF + slowest arrival time)=24 * 60 / ( total fall time x FF + slowest arrival time)

12.12. Maximum Possible Liquid Production Rate (Based on # Maximum Possible Liquid Production Rate (Based on # Cycles)Cycles)= (plgr removal effcy) ( bbls in tubing) (max cycles day)= (plgr removal effcy) ( bbls in tubing) (max cycles day)

13.13. Minutes per cycleMinutes per cycle= CPD < max CPD then 60x24/ CPD from 10= CPD < max CPD then 60x24/ CPD from 10if not then total fall time x fudge + slowest arrival timeif not then total fall time x fudge + slowest arrival time

14.14. Maximum Unloading Time, Min.. Maximum Unloading Time, Min.. =Slowest arrival time=Slowest arrival time



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15.15. Maximum Maximum AfterflowAfterflow Time, Min = Time, Min =

mins/cycmins/cyc -- max unload time max unload time –– total fall time x FF (if > 1)total fall time x FF (if > 1)

16.16. Minimum Required Gas Rate..Minimum Required Gas Rate..

if desired liquid rate > max possible liquid rate, min gas if desired liquid rate > max possible liquid rate, min gas rate rate = 400 max possible liquid rate x depth to spring/1000, = 400 max possible liquid rate x depth to spring/1000, otherwise: 400 x desired bpd x depth / 1000otherwise: 400 x desired bpd x depth / 1000



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RuleRule--ofof--Thumb Calculations:Thumb Calculations:


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Fraction of gas in Fraction of gas in Liquid Slug (80% Liquid Slug (80% is a good guess)is a good guess)

S-CurveIs used to

Determine the Gaseous Liquid Loaded Column

Gradient Below

Liquid Level

Qg < QcVSL = 0

SS--CurveCurveIs used to Is used to

Determine the Determine the Gaseous Liquid Gaseous Liquid Loaded Column Loaded Column

Gradient Gradient BelowBelow

Liquid LevelLiquid Level

QgQg < Qc< QcVVSLSL = 0= 0

~ 20% Liquid ~ 20% Liquid Actual Field Actual Field Collected Data Collected Data PointsPoints

VVSLSL = 0= 0LoadedLoadedQgQg < Qc< Qc

~ 0.08 psi/ft

~0.433 ~0.433 psipsi/ft/ft


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254.0 psi 254.0 psi –– Casing Pressure at End of the ShutCasing Pressure at End of the Shut--in period in period 199.8 psi 199.8 psi –– Tubing Pressure at End of the ShutTubing Pressure at End of the Shut--in periodin period

[A][A][B][B] [C][C]

Casing Pressure

Tubing Pressure


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65.3 psig 65.3 psig –– The Tubing Pressure Drops to Line The Tubing Pressure Drops to Line Pressure just prior to Liquid Arrival at the SurfacePressure just prior to Liquid Arrival at the Surface

[1][1] Casing Pressure

Tubing Pressure


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Average Plunger Fall Velocity in Gas:Average Plunger Fall Velocity in Gas: 279.4 ft/min 279.4 ft/min Average Plunger Fall Velocity in Liquid: 54.3 ft/minAverage Plunger Fall Velocity in Liquid: 54.3 ft/min

Looking at this MinuteLooking at this Minute

AverageAverageFall VelFall Vel

Each JointEach Joint

Falling through GasFalling through Gas


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Plunger Lift: Will it Work (Load Factor)Plunger Lift: Will it Work (Load Factor)

Load Factor: Load Factor: (Pcas (Pcas –– Ptub) /Ptub) /(Pcas (Pcas –– Pline) < 50%Pline) < 50%

(254.0 (254.0 –– 199.8) /199.8) /(254.0 (254.0 -- 65.3) = 28.7%65.3) = 28.7%

Casing Casing PressurePressure can can NOT be less than NOT be less than Tubing Tubing PressurePressure, OR , OR Plunger Stops Plunger Stops Coming to the SurfaceComing to the Surface

Pcas = 254.0Pcas = 254.0

Ptub = 199.8Ptub = 199.8

Ptub = 65.3Ptub = 65.3


1850.0

100.0

150.0

200.0

250.0

300.0

49.604 56.549 63.493 70.438 77.382

[A] [B][1] [2]

60.0

80.0

100.0

120.0

140.0

160.0

180.0

200.0

220.0

240.0

260.0

280.0

94.884 108.773 122.662 136.551 150.440

[B] [C][3] [4]

ShutShut--in Periodin Period

Note: After Reducing ShutNote: After Reducing Shut--in Time Period Based on in Time Period Based on Minimum Fall Time Minimum Fall Time

33 Minute Shut33 Minute Shut--in Time Periodin Time Period241Mscf/D. with 8 bbls of oil and 4 bbls of water241Mscf/D. with 8 bbls of oil and 4 bbls of water

68 Minute Shut68 Minute Shut--in Time Periodin Time Period168 168 MscfMscf/D with 6 bbls of oil and 3 bbls of water/D with 6 bbls of oil and 3 bbls of water

Initial ConditionsInitial Conditions

Final ConditionsFinal Conditions


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1.1. Calculations assist Plunger Lift SetupCalculations assist Plunger Lift Setup2.2. Calculated timings of plunger lift cycle Calculated timings of plunger lift cycle

compared to measurements acquired at the wellcompared to measurements acquired at the well3.3. Check Calculations Using Measured DataCheck Calculations Using Measured Data4.4. Calculation Guide the operator to effectively Calculation Guide the operator to effectively

analyze installation analyze installation 5.5. Adjust and optimize the plunger lift installation.Adjust and optimize the plunger lift installation.6.6. Increase Gas Production by Reducing Liquid Increase Gas Production by Reducing Liquid

LoadingLoading7.7. Reduce Equipment Damage and FailuresReduce Equipment Damage and Failures

RulesRules--ofof--Thumb Calculator:Thumb Calculator:Provide XLS spreadsheet to industry to easily calculate setup Parameters for controller and make adjustments to optimize Plunger Lift Installation


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Plunger Rise Velocity Plunger Rise Velocity For RuleFor Rule--ofof--Thumb Spreadsheet Example Calculations Used Thumb Spreadsheet Example Calculations Used ““Optimize BeforeOptimize Before”” WellWell

EXCEL Spreadsheets available from Echometer Co. or PLTech LLC:1) ConventionalPlungerLift_Rules-ofThumb_CalculatorPRO.xls2) Foss and Gaul Original and Modified_PlungerRiseVelocity.xls


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– Display the presentation at the Workshop.– Place it on the www.alrdc.com web site, with access to the site to be

as directed by the Workshop Steering Committee.– Place it on a CD for distribution and/or sale as directed by the

Workshop Steering Committee.Other uses of this presentation are prohibited without the expressed written permission of the company(ies) and/or author(s) who own it and the Workshop Steering Committee.


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Rule-of-Thumb Calculation of Key Events During the Plunger ...alrdc.org/workshops/2008_Spring2008GasWellWorkshop... · S-Curve Is used to Determine the Gaseous Liquid Loaded Column