WellTracerTM Technology
Gas Lift Surveillance Tool
Gas Lift Objectives and Process
 Lift as deep as
possible within
constraints of
production system
 Inject gas lift
requirements through
one single valve
station
 Maintain an optimal
gas rate under stable
or steady-state
conditions
© 2006 Weatherford. All rights reserved.
1
WellTracerTM Technology & Application
Weatherford is a licensed distributor of the
WellTracerTM Technology.
Technology developed by Shell
Over fifteen years in development
Proven in over 600 gas lift wells
© 2006 Weatherford. All rights reserved.
2
WellTracerTM Technology & Application
 WellTracer® creates a snapshot of the
well performance by injecting the CO2 into
the gas lift injection line and its
concentration is recorded at the well head
 Injected CO2 travels through the tubingcasing annulus into the tubing through
injection point/s
 Travel velocities inside tubing and casing
are used to back calculate operating lift
depth/s
© 2006 Weatherford. All rights reserved.
3
WellTracerTM Technology & Application
• WellTracer® offers a low cost effective
method to quickly and reliably determine lift
gas entry points in the well.
 Detect operating lift depth
 Detect multiple points of injection
 Detect tubing leaks
 Identifies lift gas rate through each
injection point
 Identifies how much lift gas goes to
each string of a dual completion well
© 2006 Weatherford. All rights reserved.
4
WellTracerTM Movie Clip
WELLTRACER MOVIE
© 2006 Weatherford. All rights reserved.
5
WellTracer® Advantages
• No Deferment
 Avoids shutting well in and stopping production
• Safe
 No well intervention and minimize HSE
exposure
• Accurate
 Lift depth determination directly related to
surface data
 Identifies small points of injection better than
flowing surveys
• Quick & Simple
 Minimal equipment hookup
 Able to survey at least two wells per day.
© 2006 Weatherford. All rights reserved.
6
WellTracer® Advantages
• Inexpensive
 Suitable for inclusion in regular operating
procedures
• Flexible and Deviated wells
 Suitable for cases where pressure surveys are
not feasible such as surging wells and Highly
Deviated wells
• Dual wells
 WellTracer® help analyzing the Dual wells
more efficiently
 WellTracer® establish the injection rate going
into each string more accurately and also
establishes the injection rate amount through
individual injection point
© 2006 Weatherford. All rights reserved.
7
WellTracerTM Survey Preparation
 Pre-Job Preparations:
– WT analyst, and PT’s identifies the well candidates for WT survey
– Gather current well data and operating parameters (fluid/gas rates,
valve depths, wellbore schematic)
– WT analyst and PT prepare WinGLUE models and verify all the
information in the models for the selected wells
– Record and review flowing WHP and CHP for stable flow, inspect
fluid and gas measurement equipment, review fluid/gas
measurement methods
– WT analyst run the WinGLUE model and create procedure with
estimated return times for the job
– Determine location for CO2 & N2 bottles, tapping points, sump
availability, crane, test separator, and etc
– Plan logistics with field operations personnel & supervisors during
IAP (Integrated Activity Planning)
© 2006 Weatherford. All rights reserved.
8
WellTracerTM Survey Preparation
SAMPLE PRE JOB SITE SURVEY REPORT
© 2006 Weatherford. All rights reserved.
9
WellTracerTM Survey Preparation
 On-Site Survey
– Record operating fluid level in casing with Echometer
– Setup CO2 bottle and injection manifold
– Record Injection gas measurement with Clamp-on meter
– Setup Well Tracer Analyzer unit on wellhead/flowline
tapping point
– Inject CO2 slug, monitor well, record results
– Get well test during WT survey for analysis
© 2006 Weatherford. All rights reserved.
10
Well Setup for WellTracerTM
For BSP or offshore operation in surveying gas-lift wells on a field
wide basis – plan for components which allow for easy and safe
movement to the different well sites within the constraints of the
platform facilities.
© 2006 Weatherford. All rights reserved.
11
Well Setup for WellTracerTM
© 2006 Weatherford. All rights reserved.
12
Well Setup for WellTracerTM
© 2006 Weatherford. All rights reserved.
13
Well Setup for WellTracerTM
© 2006 Weatherford. All rights reserved.
14
Well Setup for WellTracerTM
The clamp-on, portable gas meter
for both onshore and offshore is
available for confirming field gas
measurement devices
© 2006 Weatherford. All rights reserved.
15
Clamp-on Meter and WT- Comparison
WELL
NO
SINGLE / DUAL WT SURVEY
ESTIMATED GAS BASED ON
WT ANALYSIS, M3/D
INJECTION RATE – CLAMPON
FLOWMETER, M3/D
% VARIANCE
1
LRA 03 U/L (DUAL)
27,800
28,000
1
2
LRA 03 LOWER (SINGLE)
32,600
32,000
2
3
LRA 03 UPPER (SINGLE)
8,200
28,000
71
4
LRA 10 UPPER (SINGLE)
31,850
36,000
12
5
LRA 11 U/L (DUAL)
74,000
66,000
11
6
LRA 11 LOWER (SINGLE)
34,500
39,000
12
7
LRA 11 UPPER (SINGLE)
29,100
31,000
6
8
LRA 18 U/L (DUAL)
61,700
52,000
16
9
LRA 18 LOWER (SINGLE)
24,350
28,800
15
10
LRA 18 UPPER (SINGLE)
29,750
27,700
7
11
LRA 21 LOWER (SINGLE)
33,300
33,000
1
12
LRA 27 U/L (DUAL)
49,600
52,000
5
13
LRA 27 LOWER (SINGLE)
15,700
22,000
29
14
LRA 27 UPPER (SINGLE)
26,000
21,000
19
15
LRA 32 (SINGLE)
13,300
14,000
5
16
LRA 33 UPPER (SINGLE)
40,000
37,000
8
© 2006 Weatherford. All rights reserved.
16
Well Setup for WellTracerTM
A Well Analyzer – echometer –
is used for determining the
operating fluid level in the
production casing.
© 2006 Weatherford. All rights reserved.
17
WellTracerTM
© 2006 Weatherford. All rights reserved.
18
WellTracerTM Project Results

Total 56 wells (63 strings) surveyed

29 (52%) wells were found to be lifting from single point

27 wells (48%) were found to be multi-pointing, majority of which
were not identified during normal FTS

4 wells identified for the potential tubing leaks

It is estimated that 750,000 m3/day of gas is being over injected
over calculated optimum gas injection rate

The potential oil gains are estimated at 400 m3/day

WT analysis identified that the improvement needed with injection
gas allocation and metering

Average WT survey time was
4-6 hrs.
2011 Gas-Lift Workshop
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
19
WellTracerTM Project Results
Most common parameters causing over-injection and loss in production
for the problem wells.

Port erosion from the wet gas (to be confirmed after GLV
change out) and higher differential across the operating valves

Choking back the wells with PPO valves

Multi-pointing

No surface control

Leaky valves

Tubing leaks

Oversized Tubing
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
2011 Gas-Lift Workshop
20
WellTracerTM Analysis- Example 1
Well has valve interference
– Lift gas has lower CO2 concentration than produced gas
– As injection rate fluctuates, the CO2 concentration baseline
fluctuates
– Valves change out completed after WT survey and well is producing
an additional 75 m3/day of oil
Top 2 Dummy Valves
3rd WFT RF-1BL Valve (3/16”): 45%
4th WFT RF-1BL (3/16”): 43%
5th Orifice Valve (3/16”): 12%
2.2
2.0
Concentration (%)
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0:00:00 0:33:20 1:06:40 1:40:00 2:13:20 2:46:40 3:20:00 3:53:20 4:26:40 5:00:00
Time (hh:mm:ss)
WellTracer Concentration vs Time (C vs. T)
Well: [GLUE] WORK,EXAMPLE,EXAMPLE 1,23
CO2 Concentration
Total Transit 2 (2603 MD - Dummy - Dummi
Total Transit 1 (1381 MD - Dummy - Dummi
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
24-Jan-
2011 Gas-Lift Workshop
Total Transit 3 (3604 MD - Weatherford R
21
WellTracerTM Analysis
Pressure (kPag)
-0
-0
1000
2000
4000
5000
6000
Gradient plot shows valve
interference during the WT survey.
Changed 4th PPO valve to 3/16”
orifice valve and oil rate increased
by 75 m3/day.
200
400
Depth (meters)
3000
600
800
1000
1200
1400
Depth vs Pressure (D vs. P)
LIQUIDS (m 3/day)
Oil
196.70
Water
148.35
Well: [GLUE] WORK,EXAMPLE,EXAMPLE
1,23
Total
345.05
Production Pressure Model: MMSM
Measured Injection Pressure Model
GAS (m 3/day)
Form
15,000.00
Inj.24-Jan-2011
12,000.00
19:28:22
Total
26,600.00
Measured Valve Opening Pressure
Pr e s s ur e (k Pag)
G/L Ratio (m 3/m 3)
THP
Form
GOR
76.26
Measured VPC Valve670
Begin Flow
Pressure
CHP
6,033
Total GLR
77.09
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
2011 Gas-Lift Workshop
22
WellTracerTM Analysis- Example
3.4
3.2
Example 2:
Top 2 Dummy Valves
3rd WFT RF-1BL Valve (8/64”): 34%
4th Orifice Valve (12/64”): 66%
Bottom 2 dummy Valves
3.0
2.8
Concentration (%)
2.6
2.4
2.2
2.0
1.8
1.6
1.4
1.2
1.0
0:00:00
0:33:20
1:06:40
1:40:00
2:13:20
2:46:40
3:20:00
3:53:20
4:26:40
Time (hh:mm:ss)
WellTracer Concentration vs Time (C vs. T)
Well: [GLUE] EXAMPLE,EXAMPLE,EXAMPLE 2,23
24-J
CO2 Concentration
Total Transit 2 (2493 MD - Dummy - Dummi
Total Transit 1 (1552 MD - Dummy - Dummi
Total Transit 3 (3337 MD - Weatherford R
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
2011 Gas-Lift Workshop
23
WellTracerTM Analysis
Pressure (kPag)
-0
-0
1000
2000
3000
4000
5000
7000
8000
9000
Example 2:
Oil Rate= 108 m3/day
Water Rate= 186 m3/day
Formation Gas= 8,500 m3/day
Injection Gas= 23,000 m3/day
200
400
600
Depth (meters)
6000
800
1000
1200
1400
1600
1800
Depth vs Pressure (D vs. P)
Well: [GLUE] WORK,EXAMPLE,EXAMPLE 2,23
24-Jan-2011 19:21:51
Production Pressure Model: MMSM
Measured Valve Opening Pressure
Measured Injection Pressure Model
Measured VPC Valve Begin Flow Pressure
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
2011 Gas-Lift Workshop
24
WellTracerTM Analysis
18000
16000
Gas Rate (m3/day)
14000
12000
10000
8000
6000
4000
2000
-0
-0
1000
2000
3000
4000
5000
6000
Pressure (kPag)
Injection vs Pressure (I vs. P)
Well: [GLUE] WORK,EXAMPLE,EXAMPLE 2,23
Valve 3 Weatherford RF1-BL 3/16 T/C
Operating Points
Valve 4 Camco BKO-3 3/16 VPC
Design Operating Points
24-Jan-2011 19:19:36
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
2011 Gas-Lift Workshop
25
WellTracerTM Analysis- Example
5.0
Example 3:
6 GL valves
Dummy Valve in 1st and 5th Mandrel
Unloading in 2nd, 3rd, 4th Mandrel
Orifice in 6th Mandrel
4.5
Concentration (%)
4.0
3.5
3.0
2.5
2.0
0:00:00
0:33:20
1:06:40
1:40:00
2:13:20
2:46:40
3:20:00
3:53:20
4:26:40
Time (hh:mm:ss)
WellTracer Concentration vs Time (C vs. T)
Well: [GLUE] WORK,EXAMPLE,EXAMPLE 3,23
24-Jan-
CO2 Concentration
Total Transit 2 (2615 MD - Camco BKR-5 3
Total Transit 1 (1732 MD - Dummy - Dummi
Total Transit 3 (3625 MD - Camco BKR-5 3
Feb. 7 - 11, 2011
© 2006 Weatherford. All rights reserved.
2011 Gas-Lift Workshop
26
Larut 18 Dual WT Survey
9.40
11.8
9.30
11.6
9.20
11.4
Concentration (%)
Concentration (%)
9.10
9.00
8.90
8.80
8.70
11.2
11.0
10.8
10.6
8.60
10.4
8.50
10.2
8.40
8.30
0:00:00
1:06:40
2:13:20
3:20:00
4:26:40
5:33:20
10.0
0:00:00
1:06:40
2:13:20
4:26:40
5:33:20
Time (hh:mm:ss)
Time (hh:mm:ss)
DUAL LONG SURVEY
DUAL SHORT SURVEY
WellTracer Concentration vs Time (C vs. T)
3:20:00
Well: [WFTBR] LARUT,A,18,U
08-Oct-2012 16:57:54 WellTracer Concentration vs Time (C vs. T)
Well: [WFTBR] LARUT,A,18,L
09-Oct-2012 10:47:31
CO2 Concentration
Total Transit 2 (1492 MD - Weatherford R
CO2 Concentration
Total Transit 2 (1464 MD - Weatherford R
Total Transit 1 (776 MD - Weatherford RF
Total Transit 3 (1951 MD - Weatherford R
Total Transit 1 (795 MD - Weatherford RF
Total Transit 3 (1670 MD - Tubing Leak -
© 2006 Weatherford. All rights reserved.
27
Larut 18 Single WT Surveys
DUAL LONG SURVEY
10.0
12
9.8
11
Concentration (%)
Concentration (%)
9.6
9.4
9.2
10
9
9.0
8
8.8
8.6
0:00:00
1:23:20
2:46:40
4:10:00
5:33:20
6:56:40
8:20:00
9:43:20
7
0:00:00
1:06:40
2:13:20
Time (hh:mm:ss)
Concentration Vs. Time
Well: [WFTBR] LARUT,A,18 SINGLE,U
31-Aug-2012 01:35:03
3:20:00
4:26:40
5:33:20
6:40:00
7:46:40
Time (hh:mm:ss)
Concentration Vs. Time
Well: [WFTBR] LARUT,A,18 SINGLE,L
CO2 Concentration
CO2 Concentration
Total Transit 1 (776 MD - Weatherford RF
Total Transit 1 (795 MD - Weatherford RF
Total Transit 2 (1492 MD - Weatherford R
Total Transit 2 (1464 MD - Weatherford R
Total Transit 3 (1951 MD - Weatherford R
Total Transit 3 (1670 MD - Tubing Leak -
31-Aug-2012 01:20:05
Total Transit 5 (2295 MD - Weatherford R
Total Transit 4 (1942 MD - Weatherford R
SINGLE SHORT SURVEY
© 2006 Weatherford. All rights reserved.
SINGLE LONG SURVEY
28
Larut 18 Short Single WT Survey
11.0
10.8
Concentration (%)
10.6
10.4
10.2
10.0
9.8
9.6
9.4
0:00:00
1:23:20
2:46:40
4:10:00
5:33:20
6:56:40
8:20:00
Time (hh:mm:ss)
WellTracer Concentration vs Time (C vs. T)
Well: [WFTBR] LARUT,A,18,U
15-Oct-2012 10:16:53
CO2 Concentration
Total Transit 2 (1492 MD - Weatherford R
Total Transit 1 (776 MD - Weatherford RF
Total Transit 3 (1951 MD - Weatherford R
© 2006 Weatherford. All rights reserved.
29
Larut 18 Dual Short
Pressure (kPag)
1000
-0
2000
3000
4000
5000
6000
7000
8000
9000
10000 11000
200
400
Depth (meters)
600
800
1000
1200
1400
1600
1800
2000
Well Tes t Date: 14-A ug-2012 00:00:00
LIQUIDS (m 3/day)
GAS (m 3/day)
Oil
39.00
Form
13,000.00
Water
39.00
Inj.
40,722.00
Total
78.00
Total
53,722.00
Depth vs Pressure (D vs. P)
Well: [WFTBR] LARUT,A,18,UPr e s s08-Oct-2012
17:02:23
ur e (k Pag)
G/L Ratio
THP
CHP
Production Pressure Model: MMSM
© 2006 Weatherford. All rights reserved.
(m 3/m 3)
333.33
688.74
Form GOR
Total GLR
Measured
Valve Opening
Pressure
Perf Depth
2,673.00
Tubing
Water Cut
Measured Injection Pressure Model
1,724
9,411
Cas ing
Choke
Evaluation
Pr e s s ur e s (k Pag)
SBHP
18,561
Inj. Depth
FBHP
6,332
PI
Draw dow n
12,229
M
50
Measured VPC Valve Begin Flow Pressure
0.0
1,950.90
0.006
M
30
Larut 18 Dual Long
Pressure (kPag)
-0
-0
2000
4000
6000
8000
10000
Vertical Depth (meters)
500
690
702 TVD
TVD
776
795 MD
MD
1000
1128 TVD
1146 TVD
1464 MD
1492 MD
1264 TVD
1670 MD
1500
1444 TVD
1450
1449
1942
1951 MD
1668 TVD
1674
1673
2295 MD
2304
2000
Depth Vs. Pressure/Temperature
Well: [WFTBR] LARUT,A,18,L
Well Test Date: 13-A ug-2012 00:00:00
LIQUIDS (m 3/day)
GAS (m 3/day)
Oil
8.00
Form
8,000.00
Water
Inj.
20,978.00
31-Aug-2012
00:35:07 9.00
Total
17.00
Total
28,978.00
Production Pressure Model: MMSM
Mandrel 5 (Production String Entry/Open)
Measured Injection Pressure Model
Mandrel 6 (UPPO/Closed)
THP
Measured Valve Opening Pressure
Mandrel 9 (UIPO/Open)
Measured VPC Valve Begin Flow Pressure
Measured Valve Closing Pressure
Mandrel 2 (UPPO/Closed)
Mandrel 3 (UPPO/Closed)
© 2006 Weatherford. All rights reserved.
Pr e s s ur e (k Pag)
1,350
CHP
9,411
Perf Depth
Water Cut
G/L Ratio (m 3/m 3)
Form GOR
1,000.00
Total GLR
1,704.59
2,626.50
53
Tubing
Casing
Choke
Evaluation
Pr e s s ur e s (k Pag)
SBHP
18,078
Inj. Depth
FBHP
4,909
PI
Draw dow n
13,169
0.0
1,670.00
0.001
31
Larut 18 Dual Analysis
• The total estimated gas rate during Dual survey is 61,700m3/day
• It is estimated that long string is taking 34% (20,980m3/day) of the total gas
and short string is taking 66% (40,720m3/day) of the total gas.
• First Return from the short string is taking 27% (16,660m3/day), second return
12% (7,400m3/day), and third return taking 27% (16,660m3/day).
• During the short single survey, the injection rate was changed from
22,000m3/day to 37,000m3/day right at the first return was traced at the
surface.
• The return from the long string was traced after 28mins of 2nd return from the
short string and almost 1.10hrs before the 3rd return from the short string. It
shows the possible tubing leak between 2nd and 3rd mandrel depths of short
string with closer proximity to 2nd mandrel depth.
• R-1D valve for short string and long string should be open based on the
current conditions but they are not taking any gas as per WT analysis.
© 2006 Weatherford. All rights reserved.
32
Larut 18 Dual Analysis
• FL using Echometer clearly shows 3 valve stations for each string and FL is
above the bottommost mandrels for each side.
• Based on given conditions, there should not be any issue transferring to the
bottommost valves. Please verify valve details.
• WT survey was run right after valve change out. Replaced top two PPO valves
for both strings. Ran 10/64” RO-1 for short string and 8/64” RO-1 for long string
in 3rd mandrel. 4th valve is dummied for long string and short string has R-1D
valve with 1110 Psi TRO pressure.
• Showed one return from short string at 7.15hrs. Did not survey Long string
since well couldn’t flow after valve change out.
• Multi-pointing eliminated from short string after valve change out.
• Estimated injection gas rate is 23,500m3/day assuming Long string wasn’t
taking any injection gas during this Survey.
• Well test doesn’t show drop in the liquid rate for short string but long string is
producing 5 m3/day liquid (10m3/day liquid drop) after valve change out.
© 2006 Weatherford. All rights reserved.
33
Larut 18 Dual Recommendations
• The short string was taking quite high amount of gas before valve change out.
After eliminating multi-pointing issue, savings of around 17,000m3day of
injection gas has been achieved.
• The difference in the liquid rate in the well tests conducted during single and
dual short survey is not much but for the long string it shows dramatic
difference in the liquid rates (17m3/day to 138m3/day).
• There is only 4,000 m3/day of difference in the injection gas rate
(20,980m3/day during Dual long and 24,350 during Single long). Please verify
the well test conducted during single survey.
• Wireline had difficulty pulling the GLV’s. There is possible wax deposition
issue for Long string. Wireline is planning to run caliper log soon to find the
tubing leak.
• First Identify and fix the tubing leak for long string. Please run tubing pack-off
for isolating tubing leak depth for Long string.
• Pull and Investigate the issue for bottommost R-1D valve for short string if no
issue with wireline.
• Provide final recommendations once above information is available.
© 2006 Weatherford. All rights reserved.
34
WellTracerTM _ Useful Optimization Tool
• Each gas-lift well should have a WellTracerTM survey
run at least once a year to verify gas-lift efficiency or
performance.
• WellTracerTM is the only troubleshooting tool available
for accurate identification of gas injection points in
dual, gas-lifted wells.
• A consistent surveillance program can insure that all
gas-lift wells are lifting as efficiently as possible and
production is optimized with minimum well
intervention.
© 2006 Weatherford. All rights reserved.
35
WellTracerTM _ Useful Optimization Tool
• Frees up wireline to focus on other important surveillance/integrity
tasks.
 Static Pressure surveys
 Zone changes
 Other important well intervention work related to downhole
equipments such as SSSV, sliding sleeve, GLV change out and
etc
• Improve surveillance in well reservoir management workflow by
allowing wells to be reviewed each year
 It was identified that FGS is run when there is loss in the liquid
rate
 More surveillance for Gas Lifted wells will increase production,
save injection gas, compression and maintenance costs
© 2006 Weatherford. All rights reserved.
36
WellTracerTM _ Useful Optimization Tool
• WT does not require any well intervention and will virtually eliminate
any costs related to fishing and production loss due to downtime
• Team members comprising of WT analyst, Production Technologies,
Gas Lift focal point, and Reservoir Engineer can look at all the
aspects of Nodal Analysis for problematic wells fairly quickly and put
together proper recommendations to optimize the wells production. It
allows everyone involved to utilize their time efficiently to focus on
problematic wells.
© 2006 Weatherford. All rights reserved.
37
WellTracerTM Technology
QUESTIONS & DISCUSSIONS
Jayu Sadare __ +971.56.216.1902
Ron Schmidt __ +971.4.3125000 or +1.281-382-9638
© 2006 Weatherford. All rights reserved.
38