dynamic modeling of gas lift designs and...

Oct. 23 - 27, 2017 2017 Gas-Lift Workshop 1

Dynamic Modeling of Gas Lift Designs and Operations

• Jason Bigelow, Gas Lift Engineer• Matthew Clark, Gas Lift Engineer• Schlumberger

40th Gas-Lift WorkshopHouston, Texas, USAOct. 23 – 27, 2017

Oct. 23 - 27, 2017 2017 Gas-Lift Workshop 2

Agenda

• Background• Case Studies• Analysis• Conclusion

Background

• Traditional gas lift method – steady state designs• Provide services for unique gas lift situations• Dynamic modelling available to bridge the gap

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Case Studies

• Multi-point injection• Unloading vs API standard• Burst disc/long duration unloading

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Case Study 1 Multi-point Injection

• Client had issue with valve plugging• Determine if placing a deeper redundant gas lift

valve would eliminate the need for intervention• Multi-point injection concerns

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Case Study 1 Multi-point Injection

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Case Study 1 Multi-point Injection

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Case Study 1 Multi-point Injection

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0% Plugged 

25% Plugged 

50% Plugged 75%75% Plugged

Time, Hrs

GAS IN

JECTION RATE

FLOW THROUGH TOP VALVE

Case Study 2 Unloading vs API

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• First unloading on project• Well design vs changed parameters => unload• Compare with API 1 bbl/min

Case Study 2 Unloading vs API

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Case Study 2 Unloading vs API

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• 1 bbl/min – industry standard for unloading fluid through gas lift mandrel

• Risk of valve damage – flow cutting – at higher rates

• Currently using API standard for unloading to maintain low flow rate

• Determine injection rates profiles to ensure 1bbl/min is not exceeded

• Examine pressure build up in casing and tubing then compare with field data

Case Study 2 Unloading vs API

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• Initial OLGA modelling to achieve maximum of 1bbl/min during unloading

Injection Rates

Results

Case Study 2 Unloading vs API

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• Annular liquid volume

ANNULAR VO

LUME

Time, Hrs

Case Study 2 Unloading vs API

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• Annular unloading animation

Case Study 2 Unloading vs API

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• Tubing unloading animation

Case Study 2 Unloading vs API

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Gas injected through valve

Expected annulus pressure profile for successful unloading

Time, Hrs

INJECTIO

N PRESSU

RE

OLGA Predicted Rate

Case Study 2 Unloading vs API

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• Unloading case – optimization

• Maintaining 1bbl/min throughout entire unloading process

• Modelling shows a 50% reduction in unloading time over field data.

• Subject to availability of gas for unloading (natural gas versus nitrogen)

Case Study 2 Unloading vs API

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• API rates put into OGLA

Case Study 2 Unloading vs API

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• Initial OGLA model conservative to API and field data but adapting to 1 bbl/min through the valve had different slopes than API.

• OLGA model injection rates can be increased at the beginning of the process for higher rate through the valve closer to 1bbl/min to save time

• Unloading profiles match typical pressure profiles of a successfully unloaded well

• Further refinement of model completed to match field data to determine fluid rates through valve

Case Study 3 Long Duration Unloading

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• Deepwater subsea well• Burst disc in the valve• 1.5 bbl/min unloading through XLift* valve• Unloading well over months

Case Study 3 Long Duration Unloading

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• Manifolded gas injection choke

Case Study 3 Long Duration Unloading

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• OLGA model

Case Study 3 Long Duration Unloading

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• Flow through the tubes

0

0.5

1

1.5

2

2.5

3

3.5

4

4.5

5

0 1 3 4 6 7 9 10 12 13 14 16 17 19 20 22 23 24 26 27 29 30 32 33 35 36 37 39 40 42 43 45 46 48

Flow

Rat

e (M

Msc

f/d)

Time (hr)

Tube Gas Lift Flow Rates

Tube 1

Tubes 2 and 3

Tubes 4 and 5

Tubes 6 and 7

• Burst disc study• Sudden fluid rate through orifice with ruptured disc

Case Study 3 Long Duration Unloading

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• CFD model• Analyze hot spots

Case Study 3 Long Duration Unloading

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• Unloading in stages

Case Study 3 Long Duration Unloading

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Conclusion

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• Plugging top valve effects on 2nd valve• Nitrogen unloading• Burst disc and long duration unloading

Questions

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DisclaimerThe following disclaimer shall be included as the last page of a Technical Presentation or Continuing Education Course. A similar disclaimer is included on the front page of the Gas-Lift Workshop Web Site.The Artificial Lift Research and Development Council and its officers and trustees, and the Gas-Lift Workshop Steering Committee members, and their supporting organizations and companies (here-in-after referred to as the Sponsoring Organizations), and the author(s) of this Technical Presentation or Continuing Education Training Course and their company(ies), provide this presentation and/or training material at the Gas-Lift Workshop "as is" without any warranty of any kind, express or implied, as to the accuracy of the information or the products or services referred to by any presenter (in so far as such warranties may be excluded under any relevant law) and these members and their companies will not be liable for unlawful actions and any losses or damage that may result from use of any presentation as a consequence of any inaccuracies in, or any omission from, the information which therein may be contained.The views, opinions, and conclusions expressed in these presentations and/or training materials are those of the author and not necessarily those of the Sponsoring Organizations. The author is solely responsible for the content of the materials.The Sponsoring Organizations cannot and do not warrant the accuracy of these documents beyond the source documents, although we do make every attempt to work from authoritative sources. The Sponsoring Organizations provide these presentations and/or training materials as a service. The Sponsoring Organizations make no representations or warranties, express or implied, with respect to the presentations and/or training materials, or any part thereof, including any warrantees of title, non-infringement of copyright or patent rights of others, merchantability, or fitness or suitability for any purpose.