Impact of Transient Simulations on Plunger Lift Operation

Impact of Transient Simulations on Plunger Lift Operation

Rahel Yusuf, Schlumberger

Kees Veeken, Shell

Bin Hu, Schlumberger

Outline

• Introduction

• Candidate well and flow model

• Results and Discussion

• Conclusions

Slide 2

Rahel Yusuf for 9th European Gas Well Deliquification Conference & Exhibition in Groningen (Netherlands) on 22-24 September 2014

• Plunger lift is an artificial lift method mostly used to deliquify gas wells

• Plunger lift operation involves opening and closing of wellhead valveaccording to an optimum frequency to facilitate movement of plungerto surface alongwith liquid trapped above the plunger

• Low capital and maintenance cost

• Easy to install and operate

• Difficult to model as a transient modelling approach is required

Slide 3

Plunger Lift


Candidate Well

• Onshore gas well with inflow@ 2790 mAH

Slide 4


Transient Multiphase Flow Model

• A comprehensive transient multiphase simulator (OLGA) is used in the present work

• Simulator is based on three fluid model

• Solves five mass conservation equation and three momentum conservation equations

• Model has strong heat transfer calculations and solves a single energy balance for the fluid mixture

• Model extensively verified against laboratory and field data*

Slide 5

*Nossen, J., Shea, R. and Rasmussen J.: “New Developments in Flow Modeling and Field Data Verification”, 2nd North American Conference on Multiphase Technology, Banff, Canada, 21-23 June, 2000


Key Modeling Parameters

Slide 6

• 3.5” tubing to 2706 m, 7” liner to 2790 m

• Plunger between “launch” @ 2631m and “trap” @ 0

(Wellhead) and 93 m (SCSSV)

• A standing valve (SV) is placed at the plunger LAUNCH

position to prevent liquid escaping below the LAUNCH

position.

• Inflow @ 2790 , A=5.0 bara/(e3m3/d)

• Pres=15-18 bara, WGR=40-80 m3/e6m3,

• Wellhead pressure = 8 bara

• Plunger weight = 7.5 kg with zero leakage

• Plunger modelled as a PIG

• 10 plunger cycles with 2 hr flow, and1 hr shut-in


7

Temporal variation of different parameters for 10 plunger cycles

WGR=40, Pres=18, Trap @SCSSV


8

Temporal variation of different parameters for Cycle#9


Plunger Launched Plunger Trapped Well Shut-in


9

Profile plot of Tubing Holdup and Pressure@ 25.96 h


Standing Valve location


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Standing Valve locationStanding Valve location


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Profile plot of Tubing Holdup and Pressure@ 28.4h



15

Temporal variation of pressure at upstream and downstream of standing valve for

Cycle#9 with backpressure valve disabled


2.2bar


16

Temporal variation of gas rate and liquid content for different backpressure

threshold settings on backpressure valve: WGR=40, Pres=18, Trap @SCSSV


17

Zoomed in profile of tubing holdup at 28.9 h (cycle#9) with two

differential threshold pressure settings on backpressure valve



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WGR=80, Pres=15, Trap @WH


Conclusions

• Transient multi-phase flow model produces credible results andprovides valuable insight into influence of well parameters andbackpressure valve settings on plunger performance

• Plunger needs to travel to top of tubing to deliver maximumvalue i.e. liquid slug cannot bridge large “gap”

• Gas production during upward travel must deliver minimumplunger velocity and will diminish as slug size increases

• Further explore the influence of plunger launch position,wellbore (plus annulus) volume, inflow performance

Slide 22


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Impact of Transient Simulations on Plunger Lift Operation