a unique multifunctional foamer for deliquification of ......large hydrostatic caused by liquid...
TRANSCRIPT
Gas Well Deliquification Workshop
Sheraton Hotel, Denver, Colorado
February 19 – 22, 2012
A Unique Multifunctional Foamer for
Deliquification of Loaded Wells in
Canada
Duy Nguyen and Frank Cosman, Nalco Company
&
Richard Tomlins, Encana Corporation
Copyright 2012 Nalco Company & Encana Corporation. All rights reserved
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
2
Greater Sierra: Field Overview
• 800 Horizontal wells, 140 MMscfd
• Water gas ratio = 11-18 liters/1000m3 gas
• Condensate gas ratio = 5-15 liters/1000m3 gas
• Condensate water ratio = 0 to 2:1
• Salinity = 0 to 300,000 ppm
• Wet muskeg terrain, -40oC during the winter
094-I-15094-I-14094-I-13 094-I-16
094-I-10094-I-11 094-I-09094-I-12
094-I-07094-I-06094-I-05 094-I-08
094-I-03 094-I-02094-I-04 094-I-01
094-J-16
094-J-09
094-P-16094-P-13 094-P-15094-P-14
084-L-13
094-J-08
094-P-09094-P-11 094-P-10094-P-12
084-L-12
094-J-01
094-P-08094-P-07094-P-05 094-P-06
084-L-05
094-P-02094-P-04 094-P-01094-P-03
084-L-04
094-O-16
094-O-09
084-M-13
094-O-08
084-M-12
094-O-01
084-M-05
084-E-13
084-M-04
094-H-14094-H-13 094-H-15 094-H-16094-G-16
095-B-01 095-A-04 095-A-02 095-A-01095-A-03 085-D-04
094-J-15
094-J-10
094-J-07
094-J-02
094-O-15
094-O-10
094-O-07
094-O-02
094-G-15
095-B-02
084-L-14
084-L-11
084-L-06
084-L-03
084-M-14
084-M-11
084-M-06
084-E-14
084-M-03
085-D-03
084-E-12094-H-09094-H-11 094-H-10094-H-12094-G-09094-G-10 084-E-11
Petitot
Plant
D-061-
L/094-P-12
Midway
Plant
B-065-
B/094-P-04 Gunnell 1 &
2 Plant
B-023-F/094-
I-13
Sextet
Facility
B-067-J/094-
I-12 Elleh Plant
A-019-F/094-
I-12
Kyklo Plant
A-050-K/094-
I-11
Sierra Plants
1 & 2
A-026-K/094-
I-11
Infrastructure Legend
Encana Facilities
NG/SG Pipeline
Encana Sierra Assets
Northwest Territories
Alb
erta
Britis
h C
olu
mb
ia
Calgary
Edmonton
Grande Prairie
British Columbia
Alberta
Nature of Liquid Loading
Combination of factors:
• Reservoir depletion
• Water of condensation and formation water
• Liquid slugging
• Potential for static column of water in the
wellbore
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Deliquification Strategy
• Intermittent flow: Some wells may be shut in 75% of the
time in order
to build pressure to lift liquids.
• Plunger: Used in over 300 wells. Require additional
operator time and maintenance.
• Velocity strings: Used in over 200 wells. Difficulty handling
large hydrostatic caused by liquid slugs and are prone to
corrosion.
• Unsuccessful field trial of previous incumbent’s foamer in
2007 on 10 wells with capillary strings. The foamer could
not handle condensates.
• The use of foamers was revisited by Encana and Nalco in
2008 as Nalco had successfully used condensate foamers
with other gas producing companies.
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Advantages of Foamers
• Can be injected down the casing-tubing annulus
– much deeper than the plunger. However, to be
effective, the foamer has to reach and generate
foam at the end of the tubing, preventing
accumulation of liquids above the tubing.
• Low cost of the failure if the program proves to
be unsuccessful. The cost of failure for a foamer
is about $5,000 vs. $30,000 for a plunger lift
install or $75,000 for a velocity string install
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Foamer Development: Criteria for Success
• Effective in the presence of 50% condensate with
fresh water or brine
• Quick foam collapse at the well head
• A combination foamer product that contains
corrosion inhibitor and scale inhibitor
• Foamer is stable and pumpable at -43°C
• Foamer is compatible with HDPE, stainless steel,
and various elastomers
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Typical Surfactants • Nonionic :
– More soluble at lower temperature
– Increase temperature &/or salt concentration reduces solubility – lowers cloud point
– Good for wells with unknown water chemistry
• Anionic
– Excellent aqueous foamers
– Highly polar
– Can be affected by high brine solutions
– At elevated temperatures can degrade
• Cationic
– Good for foaming water/oil mixtures
– Efficacy dependant on molecular weight
– Can be prone to emulsion issues
• Amphotheric
– Very versatile : Higher condensate tolerance
– Good high temperature performance and stability
– Effective in high salt content brines
0
10
20
30
40
50
60
70
80
90
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
To
tal
Gra
ms C
arr
y O
ver
Time (minutes)
Impact of Salinity on Foaming Performance 50% condensate with 10000 ppm Foamer
5 scfh Nitrogen Flow Rate
Result: Foamer was effective in 50wt% condensate with chlorides > 4500 ppm
142 ppm Chloride 1500 ppm Chloride 4000 ppm Chloride
4500 ppm Chloride 12000 ppm Chloride 22000 ppm Chloride
32000 ppm Chloride
Laboratory Testing
NALCO’s Dynamic Unloading
Rig
Chloride
Foam Stabilizing: Area per molecule
Packing at the air-liquid interface
Air
Liquid
• Low salt
Unstable foam
Loosely packed film
- High area per molecule
Area
- - -
• High salt
Stable foam
- - - + + +
Air
Tightly packed film - Small area per molecule
Liquid
+ -
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Foam Destabilizing – Reduced Electrostatic Repulsion
- -
- - -
Stable foam
Low salt
Drainage
Liquid flows
Liquid flows
Unstable foam
High salt
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Laboratory Testing - Results
• Unloading efficiency results vary with
brine/condensate composition
• For all samples the amphoteric surfactant
showed greater potential for lifting fluids of
various concentrations when compared with
nonionic (alkyl poly glucoside) and anionic
(sulfossucinate, alkyldiphenyloxide
disulphonate) foamers
• Quick foam collapse was observed for the
amphoteric foamer
• Good separation for water and condensate (i.e.,
unstable emulsion) was observed
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Feb. 27 - Mar. 2, 2011 2011 Gas Well Deliquification Workshop Denver,
Colorado 12
Corrosion Inhibition: Linear Polarization Resistance Data
Decreased due to formation of
a protective film
Increased due to the breakdown of the film
Final 63 mpy
Final 0.06 mpy
Steep slope is an indication of a quick filmer
Gravimetric Results Sweet Conditions
Feb. 27 - Mar. 2, 2011 2011 Gas Well Deliquification Workshop Denver, Colorado
13
Blank
Treated
Corrosion Inhibition: Electrode
Photographs
Field Application: Wells Selection Criteria
• In 2009, eight (8) wells were identified for foamer applications based on the following criteria:
– A large database of LGR data.
– Multiple condensate and water analyses.
– Many years of production information and well pressure profiles.
– Operator experience with wells.
– Comparatively easy access to the well sites – a key requirement.
– Suitable well trajectory profile with no liquid trap before the end of the tubing
• Injection down casing on all wells
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
• Initial results very encouraging
Status Well Production Uplift
(e3m3/d) Comment Forward Plan
#1 4.6 2nd Lowest WGR (15 l/e3m3), some condensate (2%)
#2 2.0 Highest WGR (96 l/e3m3),
no condensate
#3 1.5 2nd Highest WGR (68 l/e3m3), no condensate
#4 0.9 4th Highest WGR (48 l/e3m3), highest CLR (15%)
#5 0.8
#6 0.6
#7 2.1 3rd Highest WGR (51 l/e3m3), no condensate
#8 -1.2 Lowest WGR (8 l/e3m3),
no condensate, large water trap
Optimize soap injection rate downward
Optimize soap injection rate upward
Optimize soap injection rate upward. Capillary string candidates
Working (continuous flow)
Positive Response (long flow periods)
Not Working (no response to soap)
Summarry
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
Soap Injection Summary
AFE Amount: $345k
Estimated Spend: $268K
Status Well On-Time Increase
(%)
Production Uplift
(e3m3/d) Injection Rate
(litres/d) Net Incremental Income
($/d)
1 50 to 100 1.9 4 162
2 33 to 100 1.6 4 130
3 26 to 99 1.2 4 88
4 38 to 100 0.8 1 75
5 39 to 79 1.2 5 78
6.7 18 533
6 31 to 60 0 4 -39
7 22 to 59 0.3 10 -66
0.3 14 -105
Dropped 8
Working
Marginal
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop Denver, Colorado
Results: Process Benefits
• No foam carryover in the vessels
• No emulsion issues noted
• Field trialled 8 wells in 2009; 38 wells in
2010; and began
37 more wells in 2011 with a success rate
of 70%
• Batch treat many other wells as needed
Feb. 27 - Mar. 2, 2011 2011 Gas Well Deliquification Workshop Denver, Colorado
17
Challenges
• High condensate to water ratio
• Salinity varies from well to well (e.g., fresh water to nearly
saturated brine)
• Difficult to deliver foamer
into the horizontal section
due to liquid traps that occur
a short distance from the
horizontal section. There is
not enough energy to cause
foaming in that section and
the liquids cause a flow
restriction in the tubing or
open hole area.
Feb. 27 - Mar. 2, 2011 2011 Gas Well Deliquification Workshop Denver, Colorado
18
1486
1488
1490
1492
1494
1496
1498
1500 1700 1900 2100 2300 2500 2700 2900 Measured Depth (MKB)
Vert
ical D
ep
th (
MK
B)
Open Hole TBG CSG
Liquid Trap
Way Forward
• Implement monitoring program to evaluate
performance of foamer’s corrosion inhibition
properties. If successful, significant cost
savings could be realized
• Ongoing expansion of foamer injection program
• Possible continuous injection through capillary
string installation to ensure the delivery of
foamer through the liquid traps
• Continued observation at the gas plant for
potential foaming issue as more wells will be on
foamer (today only about 7% of the wells are on
foamer)
Feb. 27 - Mar. 2, 2011 2011 Gas Well Deliquification Workshop Denver, Colorado
19
Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
20
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Feb. 19 – 22, 2012 2012 Gas Well Deliquification Workshop
Denver, Colorado
21
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