Downhole Gas Separation Performance Lynn Rowlanalrdc.org/workshops/2017_2017GasWellWorkshop... ·...

Gas Well Deliquification Workshop

Sheraton Hotel, Denver, Colorado

February 20 – 22, 2017

Lynn Rowlan

Downhole Gas Separation Performance

Feb. 20 - 22, 2017 2017 Gas Well Deliquification Workshop

Denver, Colorado

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Overview • Free gas interfering with liquid filling the pump is a major

operational problem producing Sucker Rod Lifted wells.

• Gas interference is when free gas at the pump intake

pressure enters the pump filling displacement volume

with gas in place of liquid, then significant loss in liquid

production and reduced drawdown occurs

• Downhole Gas Separator Simulation program predicts

how a separator will perform in the field so that the

proper gas separator and pump can be selected.

• Operators can analyze a particular separator

configuration and view how the gas separator separates

the liquid from the gas and also determine separator

capacity.

•


Denver, Colorado

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Efficiency of the Downhole Gas Separation Process

• Efficiency of the downhole gas separation

process expressed by two different methods:

1) Effective Pump Fillage % - EPF%

2) Gas Separator Efficiency %.

• Effective Pump Fillage % represents the ratio of

effective plunger travel divided by maximum

plunger travel expressed as a percent.

• Gas Separator Efficiency % percentage of free

gas at the pump intake pressure condition

vented up the casing not entering the pump


Denver, Colorado

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K Coefficient Determines Free Gas into Pump - Schmidt & Doty – May 1989

SPE 15426 Prod Engr


Denver, Colorado 5

Liquid Velocity Should be Less Than ~6”/sec Bubble Rise Velocity from Laboratory Testing

Effect of Liquid Velocity

5 inch/sec

243 BPD

6 inch/sec

275 BPD9 inch/sec

420 BPD

OK FAIL

FAIL 5 inch/sec 243 BPD

6 inch/sec 275 BPD

9 inch/sec 420 BPD

Feb. 20 - 22, 2017

2017 Gas Well Deliquification Workshop

Denver, Colorado

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Separator OK Downward Flow rate 243 BPD 5 inches /Second


Denver, Colorado

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Separator Fails Due Downward 420 BPD Flow at Velocity of 9 inches /Second

Feb. 20 - 22, 2017


Denver, Colorado

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Gas Bubbles Must Exit Gas Separator When SV Ball on Seat During SR Pumping Cycle


Denver, Colorado 9

Collar Sized Separator OK

Production of 100 BPD

with a Full Pump

Poor Boy Separator Fails

34.4” Effective

Plunger Stroke with

34% Pump Fillage

Separator Fails 141 BPD

Displacement Greater than

96 BPD Separator Capacity

Separator OK 141 BPD

Displacement Less than 242

BPD Separator Capacity

Feb. 20 - 22, 2017


Denver, Colorado

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161 Capacity Poor Boy Separator Fails Net Pump Displacement = 168 BPD @ 6.82 SPM

10

Gas Bubble Rise is

4.6 inch/sec


Denver, Colorado

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161 Capacity Poor Boy Separator OK Net Pump Displacement = 140 BPD @ 6.14 SPM

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Gas Bubble Escapes

Separator @ 4.6 inch/sec


Denver, Colorado

Low Capacity Gas Separator 2 7/8 inch Poor-Boy Separator with 60 foot dip tube 324 BPD Pump Capacity EXCEEDS 147 BPD Separator capacity

Seating Nipple

6 foot 2 7/8 sub

6 foot 2 7/8 Perforated Sub

60 Foot 1 ¼ inch dip tube

Tubing Plug

6 foot Perforated sub

Baker Latch Assembly

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Longer is NOT better

FAILS.

Feb. 20 - 22, 2017


Denver, Colorado

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$125K 147 BPD Poor Boy Separator Fails 60 Ft Long Dip tube Does NOT Help

Feb. 20 - 22, 2017


Denver, Colorado

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Tubing Anchors & Liner Tops

Tubing anchor with the

gaseous fluid column

combine to create a

choke mechanism that

regulates gas flowing

up the casing annulus

Gas Separation FAILS

due to problem of TAC

restricting annular gas

flow causing pump

filled with gas

The gaseous

liquid column

above the

TAC is 28 %

liquid with 53

MCF/D of gas

flowing

upward

through the

gaseous

liquid column.

Gas flow is

restricted

from below

the TAC.

Casing

Tubing

Liquid

Feb. 20 - 22, 2017


Denver, Colorado

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High Capacity 420 BPD Pump in the Rat Hole FAILS TAC restricts annular gas flow

Full Partial fillage

Stroke 1 Stroke 9

Dynamometer Test After 10 Minute Shut down

Feb. 20 - 22, 2017


Denver, Colorado

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Gas Separation FAILS if Pump EPF% Less than % Liquid in Annulus

Gas Separation

FAILS

Gas Separation

OK

Casing Size Limits

Gas Separation

Maximum Capacity

Feb. 20 - 22, 2017


Denver, Colorado

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Gas Separators for 4 1/2 inch Casing

Separator Type, size, inches Capacity

Natural Gas Separator 420 BPD

Collar Size Gas Separator 2 3/8 275

Poor Boy Separator 2 3/8 96

Feb. 20 - 22, 2017


Denver, Colorado

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Gas Separators for 5 1/2 inch Casing




Heavy Wall Gas Separator 2 7/8 372

Packer Type Separator 444


Feb. 20 - 22, 2017


Denver, Colorado

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Gas Separators for 7 inch Casing



Collar Size Gas Separator 4 ½ 1044

Collar Size Gas Separator 4 833

Collar Size Gas Separator 3 ½ 644


Heavy Wall Gas Separator 2 7/8 372

Packer Type Separator 1089


Feb. 20 - 22, 2017


Denver, Colorado

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Gas Separation Efficiency Determined by Gas Produced Up the Tubing and Casing

Gas Produced Up the Tubing Is Determined

From the Pump Card Calculations

Free Gas Produced Up the Tubing/Casing

Annulus Is Determined Form the Acoustic

Fluid Level Test Performed While Acquiring

the Dynamometer Test Data

Total Gas Produced Can Be Determined

System Gas Separation Efficiency Can Be

Determined By Comparing the Gas

Produced Up the Casing to the Total Gas

Produced.

Feb. 20 - 22, 2017


Denver, Colorado

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Well’s System Gas Separation Efficiency is 51.2% Equal to 9.1/17.8 MscfD

21

9.1

MscfD

8.7

MscfD

Feb. 20 - 22, 2017


Denver, Colorado

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Gas Separator Recommendations

1. Use a Natural Gas Separator unless well conditions are

unfavorable.

2. When the separator is above the producing zone, the outer

barrel of the gas separator should be about 80% of the casing

internal diameter in high producing rate wells.

3. The gas separator capacity should exceed the pump capacity.

4. Use the Echometer Gas Separator Simulator Software

Program to determine gas separator capacity.

5. Use dynamometer and fluid level analysis to determine pump

fillage and separator efficiency.

6. Determining gas separator efficiency from pump fillage when

using high slippage pumps can be very misleading since the

separator may be separating very little liquid from gas and the

actual liquid production rate may be very low.

7. The bottom of the dip tube should extend below the bottom of

the gas separator inlet ports approximately 200/SPM inches.


Denver, Colorado

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Conclusion

• Both of these gas separation efficiency methods can be

misleading and result in the operator not identifying a

well having a gas separation problem.

• Expected performance of downhole gas separators can

be calculated based on net pump displacement, size of

separator, planned SPM and a gas bubble rise velocity.

• Using K Gas Separator Performance Factor with PVT

properties does Model Field Separator Performance

• To effectively produce sucker rod lifted wells Gas

Separators should be used to within their operational

limits.

• What aout Horizontal Wells?


Denver, Colorado

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Copyright

Rights to this presentation are owned by the company(ies) and/or author(s) listed on the title page. By submitting this presentation to the Gas Well Deliquification Workshop, they grant to the Workshop, the Artificial Lift Research and Development Council (ALRDC), and the Southwestern Petroleum Short Course (SWPSC), rights to:

– 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 use of this presentation is prohibited without the expressed written permission of the author(s). The owner company(ies) and/or author(s) may publish this material in other journals or magazines if they refer to the Gas Well Deliquification Workshop where it was first presented.


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.

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.

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