development and application of foamers to enhance crude oil production
TRANSCRIPT
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Development and Application of Foamers
to Enhance Oil and Gas Production
Baker Hughes Incorporated
Scott Lehrer, Saet Byul Debord
Scott Lehrer (presenter)
Outline
• Introduction
– Life cycle of a well
– Foamer theory
• Current foamer technology
– Benefits and gaps
– On-land application of aqueous foamers
– Offshore application of condensate foamers
• Development of crude oil foamers
– Potential benefits
– Experimental methods
– Successful field application results
• Conclusions
Challenges with Mature Wells
• Decrease in reservoir pressure over time
– Fluids accumulate, creating hydrostatic pressure
– Rapid production decline
– Wells become difficult to restart
• Sometimes alleviated by mechanical unloading
– Not always best option, depending on specific well
– Requires investment in capital equipment
– Requires available space and power
Liquid
Liquid
without
foamer
Liquid with foamer
Vc
Foam
Vc
Vc = 1.593[σ1/4(ρl - ρg)1/4] /(ρg)1/2
Foamers Lower Critical Velocity
• Foam – bubbles of gas surrounded by thin liquid layer
• Foamers lower surface tension
Existing Foamer Technology
• Aqueous foamers effective for brine-rich fluids
• Condensate foamers effective with high API fluids
• Current technology ineffective for crude oil
5
Brine cut,%
AP
I g
ravit
y Traditional water-
based foamers
20
Condensate
foamer
50 100
55
45
Gap in current
technology
25
Foamers Became an Emerging Solution for
Gas Wells
• Used a broad range of aqueous surfactants
• Economic and flexible solution for on-land gas wells
• Condensate foamers also used
– Applied successfully both on-land and offshore
• Little or no capital equipment requirements
Benefits of Foamer Application
• Foamers can increase production significantly by unloading well fluids
7
Daily Production - P Hopkins 4
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Date
Dai
ly R
ate
DryVol
Oil
Water
Gas
Water
Oil
Aqueous Foamer Increased Production
((100 Mcf/D * $3.50 / Mcf) - $22.50 foamer cost/D)
* 365 * 100 wells= $12MM/y incremental revenue
Foamer Added
Offshore Condensate Foamer Application
• Synopsis from previous presentations (Mark Embrey, BHI)
– Gas Well Deliquification Workshop (Denver, 2010 & 2011)
• Offshore Thailand gas wells experience fluid loading
issues
– Reaches critical rate after 2 – 3 years
– Current solution – wells flow intermittently
– No artificial lift currently in place
– Wells shut in due to fluid loading
© 2011 Baker Hughes Incorporated. All Rights Reserved. 8
Challenges in Offshore Applications
Subsurface Safety Valve Requirement and
Surface Safety Valve Interference
• Offshore wells and on shore wells in Europe have a surface
safety valve and subsurface safety valve
• Capillary can not be hung from the top of a standard wellhead
like typical land wells installations
InjectSafe®
• Modified WRSCSSV
– Wireline retrievable surface controlled sub-surface safety valve
– Provides chemical flow path around flapper valve
– SCSSV still fully functional
– No workover required
• Wellhead Adapter
– Capillary hung below all tree valves
– Still have access to BPT
– Maintain full functionality of wellhead
Offshore Capillary Trials
• Performed trials on 3 wells in Gulf of Thailand in January
2009
• Ran capillary to set depth and pumped foamer while
flowing the well for several days
• Results were promising and led eventually to a permanent
installation
• Example presented is from Funan Field, Well #9
– Fluids produced > 80% condensate
Results of Condensate Foamer Application
© 2011 Baker Hughes Incorporated. All Rights Reserved. 12
• Adding condensate foamer increased gas production by unloading
well fluids
Drastic production
decrease before foamer
Potential Foamer Benefits in Oil Wells
• Increase production of flowing wells
– Alleviate liquid loading by reducing fluid density
– Increase oil and gas flow, reduce downtime
– Alleviate slugging
• Supplement gas lift when inadequate
– Insufficient gas supply to optimize gas lift
– Gas lift mandrels located well above end of tubing
• Restart wells shut in for maintenance
Oil Foamer Lab Test
• Fluids added to foam
column, sparged with gas
and preheated
• Fluid volume measured
• Fluids treated with foamer
• Foam volume measured
during test
New Oil Foamer Requirements
• Identify appropriate chemistry to foam crude oil
• Perform in a wide range of oils
• Have flexible application methods
– Capillary, batch, gas lift
• Stable in the well bore environment
• Resulting foam responsive to typical defoamers
• Has no impact on asset integrity
Two Oil Foamers Developed
* Oil foamer A passed “gunking” qualification test
Oil foamer A Oil foamer B
Gas lift
application? Yes * No
Capillary approved 300F 200F
Oil Foamers Evaluated in Multiple Fluids
• The recommended dosage is based on lab tests. The
dosage would be optimized during the field application.
Well # 1 2 3 4 5 6
BOPD 1630 600 850 50 340 315
BWPD 20 30 90 50 185 270
API gravity 30 33.5 32 40 34.5 36.3
Bottom hole
F 137 192 133 300 183 168
Via Gas lift? No Yes Yes No Yes Yes
Oil foamer
tested B A A A A A
ppm 5,000 2,000 1,000 1,500 2,500 500
Oil foamer
effective? Yes Yes Yes Yes Yes Yes
Foamer Technology Extended to Treat Crude
Oil
• Enhance production without water quality issues
• Effective in lab testing with crudes 25 to 40 API
• Water cuts 0% to 60%
Brine cut (%)
AP
I g
ravit
y Traditional water-
based foamers
20
Condensate
foamer
40 100
45
25
35 Novel Oil Foamer
Background
• Well depth: 10,000 ft (3048 m)
• Bottom hole temperature: 300°F (149°C)
• 50% brine / 50% oil; API 40°
• Aqueous foamer capillary applied to near bottom hole
• Retention time only 5 minutes due to small gas/liquid
separator
Production History
• Cycling production – 7 days on, 7 days off
• Historical production
– 250 Mcf/D gas, 40 BOPD, 40 BWPD
• 60 days before trial
– 122 Mcf/D gas, 13 BOPD, 9 BWPD
• Aqueous foamer unable to maintain production
Laboratory Results
• Baseline fluid contained 1500 ppm aqueous foamer
• Baseline fluid did not reach unloading threshold
• Unloading occurred with 1500 ppm crude oil foamer
0
200
400
600
800
1000
1200
0 500 1000 1500 2000
Flu
id V
olu
me
(m
L)
Crude Oil Foamer (ppm)
Unloading
started
Unloading threshold
Field Trial Procedure
• Discontinued aqueous foamer and flushed capillary
• Applied 750 ppm oil foamer downhole via capillary
• Defoamer added upstream of separator
• Measured gas, oil, and water production
• Monitored foam carryover potential by “rag test”
• Collected water samples to evaluate emulsification
Field Trial Results –
Incumbent vs. Oil Foamer
• Production time extended to 11 days from 7 days
• Gas and oil production rates more than doubled
0
20
40
60
80
100
120
0
100
200
300
400
500
600
Mcf/
D
Gas
Oil
BO
PD
Oil Foamer
injected
Field Trial Results – Revenue Impact
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
Average Net Revenue /Day
$/D
ay
60 Day Incumbent 7 Day Trial
Based on $75/barrel crude, $4/Mcf
Field Trial Results – Water Quality
Produced Water Quality
w/ Aqueous Foamer
Produced Water Quality
w/ New Oil Foamer
Conclusions
• Foamer injection is a viable method to enable wells with liquid
loading issues to be returned to continuous flowing status
• Capillary injection systems are emerging as a viable option for
offshore applications
• Oil foamers developed effective in lab testing over a wide range
of crude oils
• Potential benefits of oil foamers identified include enhancing
flowing well production and restarting wells
• Oil foamers were formulated for multiple application methods
• Field trial confirmed oil foamers’ effectiveness
– Increased run length, oil & gas production
– No negative impact on water quality, oil/water separation
– Foam controlled with conventional defoamers
Acknowledgments
The authors would like to acknowledge Baker Hughes, Inc. for allowing
us to publish this paper
The authors thank Carlene Means for her contributions in
development of the crude oil foamer and Simon Crosby, Gus Fuentes,
Jeff Long, in Baker Hughes production operations for supporting the
field trial in south Texas
The authors thank Mark Embrey for his contributions to this
presentation
The authors also thank EOG Resources for providing a location to
field trial the new foamer technology and for their assistance during
the trial