1. FOAMER APPLICATION IN A 36” GAS PIPELINE: A SUCCESSFUL CASE OF LIQUID UNLOADING
Claudio Passucci , Alberto Di Lullo, Paolo Omarini, Marco Montini - eni
Francesco Pitassi , Filiberto Placca, Mario Grippo - Baker Hughes
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2. 2015 Gas Well Deliquification Workshop Denver, Colorado
Agenda
Pipeline deliquification techniques
pigging vs foaming
Foamer technology
Case study
Candidate identification and field monitoring
Flow assurance numerical study
Field trial design and application
Field trial main technical and economic outcomes
Conclusions
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

3. Drawbacks of liquid accumulation into pipelines
More frictional pressure drops due to a reduced hydraulic section available to the flow (in horizontal pipes)
Increased back pressure due to hydrostatic head in the vertical sections (i.e. risers, pipe line to shore)
Risk of severe slugging (in risers)
Liquid surges may jeopardize production and also affect the integrity of the equipments (overpressure, carry-overs,…)
Corrosion by the presence of stagnant water
I vantaggi della deliquification sono simili a quelli che si hanno per applicazioni in pozzi
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

4. Pipeline deliquification techniques
PIGGING
Advantages
Able to remove almost all the settled liquids
Able to remove solids
Proven technology
Drawbacks
Operator reluctance (stuck pigs)
May be unfeasible due to unpiggable lines, geometric constraints or absence of pig traps
Induce a large and sudden liquid surge
FOAMING
Advantages
Not intrusive
Done while producing at the normal rate
Limited risk of causing liquid slugs
Drawbacks
Less efficient than pigging (cannot remove deposited solids & all the settled liquids)
Proven for wells, just few pipeline applications
Need of a defoamer to prevent any foam carryover to the process
Confronto tra pigging (tecnologia consolidata) e foaming. Sottolineare che le applicazioni di foamer in pipeline sono poche rispetto a quelle in pozzo che sono note e comuni
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

5. Foamers working principle: surfactant
Lowers density of the liquid droplets
Droplet size reduced by lowering surface/liquid surface tension
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

6. Pipeline deliquification: the case study
Offshore gas brown field in Egypt (Nile Delta Area)
Production sharply declining
Reported slug issues causing trip of the onshore compression station
Lean gas (CGR< 1 bbl/MMSCF)
36”, 31 mi (50 km) pipe line transporting raw gas from A-platform to the onshore process plant
Not pigged for long time: excessive risk of stuck pig
Candidate for Foaming Trial
I triangoli sono subsea wells, I quadrati sono piattaforme
Non c’è processo offshore, separation e boosting è a terra (process plant)
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

7. Pipeline deliquification by Foaming - Workflow
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2015 Gas Well Deliquification Workshop Denver, Colorado

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Pipeline deliquification – before the trial
Data collection (fluid composition, gas/liquid rate, pressure and temperature, pipeline ID, etc…)
Installation of dedicated instruments (portable PT gauges and gas flow meters)
2 Pressure loggers (1 on A-platform, 1 Onshore)
1 ultrasonic gas flow meter (slug catcher gas outlet)
Pressure logger
Ultrasonic flow meter
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

9. Pipeline deliquification: hydraulic study
Perform a hydraulic study
OLGA™ dynamic multiphase simulator (version 7.2)
Check the fluid-dynamic (hold-up, pressure, gas velocity, etc…)
Estimation of the amount of settled liquids
INPUT DATA
Average Gas rate: 100 MMSCFD
Gas sp. Gravity (air=1): 0.550
Average Water rate: 190 – 380 bbl/d
Pipeline length: 31 mi
Pipeline ID: 34” ¼
Outlet pressure: PSI
Inlet temperature: 86 ºF
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

10. Pipeline deliquification - hydraulic study
Main outcomes:
The pipeline contains almost bbl of liquids (mainly water)
The max. expected reduction in inlet pressure for complete deliquification is about 14.5 PSI (1 bar)
In alto, profili. Il max gain in pressione è la differenza tra la P calcolata e il minimo della curva. Questo perchè la parte a sinistra della curva dipende dalla idrostatica.
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2015 Gas Well Deliquification Workshop Denver, Colorado 10

11. Chemical Selection & Characteristics
Selected in the lab by foaming and defoaming column test
The foamer agent selected is an aqueous/alcohol solution of surface active components. It can be used via batch or continuous application to treat gas wells & pipes
Main characteristics:
PRODUCT F1
Pour Point ºF (ºC)
-5 (-21)
Capillary approved/Temp tolerance ºF (ºC)
180 (82)
Combination/Type (CI or SI) No
Flash Point ºF (ºC)
86 (30) pH
comment
Effective foamer for heavy brines and high condensate levels.
Extensively used in onshore and offshore Europe
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

12. Pipeline deliquification – the trial
Foamer injection at A-platform
Rate: 4.4 gph, volume: 530 gal - 5 days injection
Defoamer injection onshore:
Rate: 5.5 gph, Volume: 1320 gal - 10 days injection
System monitoring by ad hoc portable instrumentation
Liquid sample at slug catcher outlet
Check for absence of foam
Flow meter a ultrasuoni (non intrusivi). PT, portable gauges
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

13. Pipeline deliquification – production increase
Peak gas rate
Estimated prod. increase
L’area tra le due linee (quella tratteggiata e quella continua) è il guadagno del foamer. Dopo il foamer il declino è più steep perchè dovuto al duplice effetto della deplition e del ri-accumulo di acqua in linea. Una volta finito l’effetto del foamer il declino riprende lo stesso trend di prima del test.
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

14. Pipeline deliquification: main outcomes
Gas production peak: 5.3 MMSCFD (+5%)
Average production increment of about +2.5 MMSCFD with respect to the expected production decline.
Backpressure reduction 7.25 PSI (0.5 bar) immediately after the test, effect visible for about 3 weeks
Cumulative production increased 53 MMSCF (+2.2%)
KPI: 30 MSCF/gal of chemicals (foamer + defoamer)
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

15. Pipeline deliquification: conclusions
Foamers are effective in reducing the liquid loading in raw gas transporting pipelines
A successful application on a 36” x 31 mi pipeline has been performed by eni in Egypt
Hydraulic studies have been a key factor for the candidate selection and design of the chemical treatment
The pressure reduction has led to an increased gas recovery of about 53 MMSCF (+2.2%) over 3 weeks
Continuous treatment would further increase the profitability by optimizing chemicals consumption
Feb
2015 Gas Well Deliquification Workshop Denver, Colorado

16. 2015 Gas Well Deliquification Workshop Denver, Colorado
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2015 Gas Well Deliquification Workshop Denver, Colorado

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Disclaimer
The 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 Well Deliquification Web Site.
The Artificial Lift Research and Development Council and its officers and trustees, and the Gas Well Deliquification 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 Well Deliquification 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.
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Feb , 2015
2015 Gas Well Deliquification Workshop Denver, Colorado