Presentation

Gas Well Deliquification Workshop
Sheraton Hotel, Denver, Colorado
February 17 – 20, 2013
Optimal Dead-Leg Tubing Length in
Long Perforated Completion Intervals
Matt Vivian, Production Engineer
Alec Walker, Reservoir Engineer
Shell Exploration and Production Company
Overview
Problem Statement
Dead-Leg Tubing Configurations are a good solution for
Long Completion intervals; however Plunger Lift cannot
unload the entire Dead-Leg and flow rates are often
below critical rate
Background
Tubing Configurations in Long Completion Intervals
• Deeper tubing is better (multiple SPE Papers)
• Plungers can unload fluid in High LGR wells with enough
energy
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
2
Pinedale Setting
• Green River Basin
• 6,000’ of stacked
discontinuous
tight gas sands
• Completion depths
8,000’ to 14,000’
• Produce 50-70
sands commingled
• 400 psi line
pressure
• Condensate (CGR) ~7 bbls/MMCf (LGR = CGR + WGR)
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
3
Summary
Lessons Learned
Dead-Legs improve production where wells lack
sufficient energy to flow around end of deep tubing
• Minimizing the Dead-Leg Length will improve
production/recovery
• Timely tubing and lift installation increases success
• Starting Deep and Raising the Entry Point with time as
Downtime increases improves results
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
4
Pinedale Tubing Configurations
• 4.5” production casing
Conventional
String
EOT Flow Top Dead
Dead-Leg
Perf
• 2.375” tubing with Plunger Lift
• Live annulus
• Low WGR flow around EOT
• High WGR flow in Dead-Leg
configuration (> 70 bbls/MMcf)
6,000’
• EOT 200’ above bottom perforation
– EOT flow: minimizes water column
– Dead-Leg flow: reduces flow area
Bottom
Perf
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
5
Solutions to High WGR Challenge
Production Challenges
• Low flow deep in annulus results in liquid
accumulation
– Plunger Lift can only cycle to Dead-Leg entry point
– Annular area 2.5X tubing area
– Annular critical rate 1.5-2X tubing critical rate
(Turner)
• Increasing Dead-Leg OD increases velocity but
comes with added risk
– Annular area still 1.8X tubing area
– Below critical rate without a plunger to unload
• Gas Lift & Pumps w/ Back-Pressure Reduction are
long-term solutions (2013 GL Trial for Economics)
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
Dead-Leg
Dead String
Dead-Leg Setups from
Field Learnings
2 3/8" Deadleg Tubing
with SSD or Perforated Joint
Top perf
New SOP
Gas downward
flows down
in Casing
flow
in Casing
above SSD
• Liquid level assumed at entry point
so set as deep as WGR allows
• WGR 70-100 initially EOT flow, but
expect to raise in a year to 75%
– In past used 75% @ ~12,000’
• WGR > 100 bbls/MMcf setup @
50% or Deeper 75%
Sliding Sleeve
(Open)
Location
25-75% of
perf interval
Fluid Gradient
<0.43 psi/ft, but
likely zones
covered in
water and gas
– Previously started @ 25% ~9,000’
• Raise entry as Downtime dictates
• WGR < 70 EOT flow for well life
Feb. 17 – 20, 2013
~Liquid Level
X or XN nipple
(W/ PXN Plug)
End of tubing
2013 Gas Well Deliquification Workshop Bottom perf
Denver, Colorado
Gas
Gas upward
flows up
flow
in Casing
in Casing
below SSD
below
Well 1- Low WGR not Optimal in DeadLeg as Plunger cannot clear fluids
• Average Production Rate: 1 MMcfd
• LGR: 37 bbls/MMcf
• Gross Interval: 8,022 – 14,296’
• Tubing Dead-Leg Entry Point: 7,747’
Top
Perf
P4
• Cap String Injection Point: 12,462’
• EOT: 14,138’
• Four Permanent Pressure Gauges
• P3 not transmitting
• As rate has declined all pressure
gauges stopped transmitting
P3
EOCS
P2
EOT
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
P1
8
Well 1
2 -–Pressure
and Rate
Response
to Pressures
Surfactant Injection
Well
Dead-Leg
Bottom
Hole
2,200
Gas Rate (Mcfd) and Pressure (psi)
Well
2
2,000
Tubing Pressure
Gas Rate (Mcfd)
Casing Pressure
Downhole Pressure
1,800
1,600
Typical EOT Flow well of same WGR has BHP ~1400 psi
1,400
1,200
1,000
800
600
400
200
0
1-Dec
16-Dec
31-Dec
15-Jan
30-Jan
Low WGR Well Sub-Optimal as Plunger cannot unload Dead-Leg
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
9
Well 2 - Pressure
Gradient
Change
with Surfactant
Well 1 – Dead-Leg
Deep
Pressure
Gradient
higherInjection
than Shallow
0.350
Well 2
Shallow Gradient
Deep Gradient
Pressure Gradient (psi/ft)
0.300
P1-P2 (13,847’-13,152’)
0.250
0.200
0.150
P2-P4 (13,152’-7,820’)
0.100
0.050
1-Dec
16-Dec
31-Dec
15-Jan
30-Jan
Shallow Entry Point at 0% (Top Perf) is NOT effective
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
10
Deeper Dead-leg is Better to a point
• ASSUMPTION: If the well can flow without loading up
then deeper entry point is better
• Well #2 Initially EOT flow unsuccessful due to low
energy (late) and no plunger
• Shallow Dead-Leg @ 25% works, but is it Optimal?
• Well #2 entry point was deepened 2,800’ (to 75%)
– Even if takes time to dry out formation from flowing casing for
months with Tubing Holes saw Uplift
• Plunger cycling from 2,800’ deeper results in:
– ~1,200 psi lower BHP on bottom 6 stages below entry point AND 8
stages above entry point
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
11
on
gR
evis
i
Cumulative Gas Produced : 2165.56 MMcf
10000
1000
1. 11/25/2008: Install Tubing - Straight tbg w/ Closed SSD @ 9,544'.
Well 2 - Mthly
Wir
elin
e Tu
bin
2. 07/29/2009: Wireline Tubing Revision - Opened SSD & Set plug in X
3. 06/10/2010: Continous Treatment - Foamer started
5000
4. 06/23/2011: Plunger Lift - Plunger Cycling
500
5. 08/13/2012: Tubing Revision - P2 of 5: Converted well from 25% En
6. 08/14/2012: Tubing Revision - P3 of 5: Replaced tubing up to SSD
ubin
g
WGR 66
ift
T
Wuirbi
enlin
geR
Teuvbis
iogn
in
Rev
isi
on
Plu
nge
rL
atm
e
Co n
ti
no u
s
T re
Inst
a ll T
• 11/08 Tubing Install
Late @ 95% with
61% Downtime
(DT)
nt
7. 08/22/2012: Wireline Tubing Revision - P4 of 5: Opened SSD @ 12,3
1000
100
Cumulativ e Water Produced : 134.99 Mbbl Cumulativ e Oil Produced : 14.87 Mbbl
Cumulativ e Water Produced : 134.99 Mbbl Cumulativ e Oil Produced : 14.87 Mbbl
• 8/09 @ 25%10000
with
10000
1% DT
500
50
1000
1000
5000
• 8/12 @ 75% 5000
for >
90 days & 0% DT
• If Initially set EOT
Flow with Plunger?
Feb. 17 – 20, 2013
Cumulativ e Gas Produced : 1885.48 MMcf
Cumulativ e Gas Produced : 1885.48 MMcf
100
Axis 1 BOULDER 11B-32D
Axis 1 BOULDER 11B-32D
Calendar Day Gas Rate ( Mcf/d )
Calendar Day Gas Rate ( Mcf/d )
Producing Day Gas ( Mcf/d )
Producing Day Gas ( Mcf/d )
500
500
GasFcst2012IPSC ( Mcf/d )
GasFcst2012IPSC ( Mcf/d )
GasFcst2011IPSC ( Mcf/d )
GasFcst2011IPSC ( Mcf/d )
Axis 2
Axis 2
RatioWGR ( bbl/MMcf
) BOULDER 11B-32D
1
RatioWGR ( bbl/MMcf
) 2BOULDER3 11B-32D 4
2007
08
09
10
11
1000
1000
67
5
10
12
Date
100
100
2013 Gas Well Deliquification Workshop
Denver, Colorado
12
1600
PD
PD
85
PS
PD
94
PS
PD
PD
PD
1400
Well 2 - Daily
1200
1000
800
• Black Casing
Pressure about
same with deeper
entry point
• Blue Tubing
Pressure
• Red Daily Gas
100 Mcf/d Uplift
600
1250
400
Daily Gas Rate (Mcf )
ALIAS WARBONNET 12-14D
200
0
1000
25%
Entry
7/1/2011 12:00:00 AM
Tubing Pressure
Tubing
Holes
75%
Entry
549.04 days
Casing Pressure
12/31/2012 12:00:00 AM
750
500
250
0
JUN
JUL
Feb. 17 – 20, 2013
AUG
SEP
OCT
NOV
DEC
JAN
FEB
MAR
APR
2011
MAY
JUN
JUL
2012
Date
AUG
SEP
OCT
NOV
DEC
13
First Criteria: Production Gains
• Compare production before and after entry point
change (23 wells)
Example Well
Production (MMSCF/d)
1.8
1.6
Data Set 2
1.4
1.2
1
Data Set 1
0.8
0.6
Entry Point
Change
0.4
0.2
0
6-Feb
Actual Production
28-Mar
17-May
6-Jul
25-Aug
14-Oct
• Ratio of Data Set 1 to Data Set 2 can be compared for
different entry point depths
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
14
Deeper Dead-Leg is Better HOWEVER
Raising Dead-Leg Yields Good Results
• RESULTS: Once the well loads up regularly and
difficult to kick-off Raising Dead-Leg Entry helps
• Average 40 Mcf/d Uplift and 30% reduction in decline
• 23 well study
• 17 Good (Avg
167 mcf/d)
• 6 Bad (Avg -79
mcf/d)
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
15
First Day of Production 8/1/2007
Good: Well 3 – 145 Mcf/d Increase
3000
Cum Prod WGR = 59
1729.67896
1729.96106
498.50110
2500
Red = Gas Rate (Mcf/d)
Black = Casing Pres. (psi)
Blue = Tubing Pres. (psi)
2000
96% Entry
52% Entry
1500
1000
500
0
7/29/2011 12:00:00 AM
150 Days
150 Days
9/29/2011
123.04 days
7:00:00 AM
11/29/2011 12:00:00 AM
Entry Point Changed 9/29/2011
FROM: EOT @ 13,005’, 96% down perf
zone
TO: SSD opened @ 10,410’, 52% down
perf zone
16
First Day of Production 12/1/2007
Bad: Well 4 – Lost 109 Mcf/d
3/1/2012 12:00:00 AM
2500
2000
Cum Prod WGR = 102,
Recent AVG WGR = 150
48% Entry
24% Entry
1500
1000
500
0
6/29/11
Tubing Pressure
143 Days
7/27/11
8/24/11
9/21/11
Casing Pressure
Vol Gas Yest
60 Days
11/16/11
12/14/11
1/11/12
2/8/12
Entry Point Changed 12/13/2011
FROM: SSD1 Open @ 10,616’, 48% perfs
TO: SSD2 open @ 9,284’, 24% down perfs
In 2009 SSD2 Open w/ 3% DT, but
below 430 Mcf/d DT increased (Now
Less Energy in Dead-Leg so fluid kills?)
Uplift (Mcf/d) vs Old Entry Point (depth)
Conclusion
• EOT flow
wells had
the most
benefit
raising
• Wells
already
Shallow
had zero or
negative
benefit
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
18
Uplift (Mcf/d) vs Downtime (% Offline)
Conclusion
• Large
Downtime
wells had
the most
benefit
• Wells with
limited
downtime
had zero or
negative
benefit
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
19
Second Criteria: Downtime %
• Review each wells Downtime % (mostly liquid loading)
– 297 entry points from 165 wells w/ WGR > 55 bbls/MMcf
– Overall Downtime % calculated by Day Online vs Days in Month
• ASSUMPTION: Where > 3 months < 10% Downtime
believed success
– Determine # Days < 10% Downtime
– Determined Rate at which Average Downtime became > 10%
– Compared Success vs Plunger Lift Installed
• NOTE: Plunger Lift (PL) Installed in High WGR wells
mostly in 2011/2012 with Dead-Legs (Late)
– 30 wells PL entire entry point + 67 PL added after entry point
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
20
# Days Effective Flow vs WGR: Wells
w/ WGR >55 bbls/MMcf
Conclusion
• Many wet
wells flow
>6 months
in given
Entry Point
• 103 Entry
Points Not
effective as
Rate Low,
No Lift, or
Other
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
21
Avg Rate Downtime Increased vs WGR:
Wells w/ WGR >55 bbls/MMcf
Plunger Lift
Installed
Only wells
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
Lower
Rates
22
EOT Flow (Entry Point >85%)
• WGR < 100
EOT Flow
typically
effective >
6 months
• 44 of the 56
NOT
effective
did not
have
Plunger Lift
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
23
Dead-Leg Entry Point < 75% w/ Plunger
More Effective if WGR > 100 bbls/MMcf
Entry Point 75% & EOT
Entry Point 25% & 50%
More
Points
Fewer
• Less points on Zero Days Effective line
• More points with WGR > 100 flowing > 6 months
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
24
Cumulative Gas Produced : 1885.48 MMcf
10000
1000
5000
500
Tu b
ing
Rev
isio
n
• 4/10 @ 96%
with 64%
DT
10000
10000
10000
10000
even with PL
Inst
a ll T
• 2/09 @ 75%
for 334 days
& 8% DT
ubin
g
WGR 86
1000
Cumulativ e Water Produced : 134.99 Mbbl Cumulativ e Oil Produced : 14.87 Mbbl
Cumulativ
e Water
Produced
: 134.99
Mbbl Cumulativ e Oil Produced : 14.87 Mbbl
Cumulativ
e Water
Produced
: 134.99
Mbbl
Cumulativ e Oil Produced : 14.87 Mbbl
Cumulativ e Water Produced : 134.99 Mbbl
Cumulativ e Oil Produced : 14.87 Mbbl
500
5000
• 9/11 @ 50%
5000
5000
5000
for >398 days
& 9% DT
100
Axis
1 1BOULDER
11B-32D
Axis
BOULDER
11B-32D
Axis
1 1BOULDER
11B-32D
AxisCalendar
BOULDER
11B-32D
Day
Gas
Rate
( Mcf/d
) )
CalendarDay
DayGas
Gas
Rate
( Mcf/d
Calendar
Rate
(
Mcf/d
))
Calendar Day
Day Gas
Gas (Rate
( Mcf/d
Producing
Mcf/d
)
Producing DayGas
Gas( Mcf/d
( Mcf/d) )
Producing
ProducingDay
Day Gas
( Mcf/d
GasFcst2012IPSC
(
Mcf/d
) ))
GasFcst2012IPSC( Mcf/d
( Mcf/d
GasFcst2012IPSC
GasFcst2012IPSC( Mcf/d
( Mcf/d)) )
GasFcst2011IPSC
GasFcst2011IPSC ( Mcf/d) )
GasFcst2011IPSC
GasFcst2011IPSC( (Mcf/d
Mcf/d )
Axis
22
Axis
Axis
22
AxisRatioWGR
( bbl/MMcf
) BOULDER
11B-32D
RatioWGR
( bbl/MMcf
) BOULDER
11B-32D
RatioWGR
RatioWGR( (bbl/MMcf
bbl/MMcf) )BOULDER
BOULDER11B-32D
11B-32D
08
100
50
Cumulativ e Gas Produced : 1885.48 MMcf
Cumulativ
e Gas
Produced
: 1885.48
MMcf
Cumulativ
e Gas
Produced
: 1885.48
MMcf
Cumulativ e Gas Produced : 1885.48 MMcf
2007
Inte
rmit Plu
ter nge
r L if
Co n
t
t
i
n
o us
Wir
elin
e Tu T re atm
en
bin g
Rev t
isio
n
Well 5
09
10
1000
1000
1000
1000
500
500500
500
10
11
12
Date
1000
1000
Feb. 17 – 20, 2013 1000
1000
2013 Gas Well Deliquification Workshop
Denver, Colorado
100
100100
100
25
Dynamic Dead-Leg
over Time is Best
1) 2 3/8" Tubing to
Bottom (EOT Flow)
& Plunger to
Bottom
2) 2 3/8" Tubing
3) 2 3/8" Tubing
Holes Punched with Holes Punched with
Slickline @ 75%
Slickline @ 50%
Top
perf
• Starting deep and
moving uphole with
tubing punches
maintains lowest BHP
• Plunger Cycling to Entry
Point is most effective
• 54 of 73 Plunger wells
with WGR > 70
bbls/MMcf are effective
in Dead-Legs of 25% to
75% of completion
interval
Feb. 17 – 20, 2013
10 - 1/4"
Holes
@ 10,500'
10 - 1/4"
Holes
@ 12,000'
XN
nipple
End of
Tubing
XN nipple
PXN plug
Bottom
perf
2013 Gas Well Deliquification Workshop
Denver, Colorado
26
Conclusions
• Optimal Well Performance requires Dynamic Dead-Leg
Configurations
– Starting deep and moving uphole improves overall production
– Downtime and Plunger Optimization will dictate timing to move
Entry Point uphole
• Timely tubing and lift installation increases success
– Maintains deeper entry point longer and lower BHP
– Near Wellbore Formation Damage from Liquid Loading reduced
• When well has energy it can flow around EOT with
minimal downtime; then need Dead-Leg
– WGR < 100 bbls/MMcf can flow without Dead-Leg initially (EOT)
– WGR > 100 start with short Dead-Leg and lengthen as needed
Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
27
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Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
28
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Feb. 17 – 20, 2013
2013 Gas Well Deliquification Workshop
Denver, Colorado
29