1. By: Gatut Widianoko Weatherford Artificial Lift Systems
Gas Lift Optimization at BP-Indonesia Dual String Gas Lift Well With Injection Pressure Operated Valve
By: Gatut Widianoko
Weatherford Artificial Lift Systems

2. Abstract
North West Java Oil (NWJO) field located offshore Indonesia is operated by BP. This mature oil field (discovered during 1970’s) has approximately 950 wells, and ninety percent (90%) are produced with dual gas lift systems. In thirty (30) years of production, the reservoir pressure has decline to an average between 500 – 600 psig at the mid-perforation depth (ranging from ft TVD). Discharge pressure of lift gas is 680 psig at compressor station(s).
In June 2001, BP-Indonesia management made a decision to focus on optimizing their gas lift wells. After significant discussion, it was decided to take a non-conventional approach with respect to gas lifting dual wells by using Injection Pressure Operated valves (IPO’s).
Process Overview:
create effective optimization organization
design of dual gas lift utilizing IPO valves
experiences and solutions for eliminating “gas
robbing”.

3. Offshore Northwest Java Oil Field

4. Steps in Gas Lift Optimization
BP Management - focus on gas lift optimization
90% of wells produced by dual gas lift
Optimization Team selected
Team reviews in-house (limited) gas lift expertise; decision made to contract gas lift services from Weatherford; GL engineer visits Jakarta office and NWJO field facilities
Optimization Team reviews report; proposals submitted Weatherford; further discussions held regarding project
Optimization Team contracts three (3) positions for implementation of NWJO project for 6 month period (including clause for additional 6 month extension)
Objectives determined and proper means of tracking or trending established; workable reports
Results of optimization reviewed weekly and monthly

5. Gas Lift Optimization – Team Objectives
Identify problem wells or common well problems
Improving oil production rate
Optimizing gas injection
Reviewing well performance
Maximize overall potential
Stabilize oil production and gas injection

6. Contracted Job Titles OFFICE JOB – Gas Lift Engineer
Gathering reservoir & production data
Reviewing gas lift performance & current GL design
Generating recommendations
WORKSHOP JOB – GLV Technician
Calibration and repair all gas lift equipment
Manage gas lift equipment inventory & inventory reports
FIELD JOB – Gas Lift Specialist
Installing, tuning & troubleshooting GL wells
Training company field operators (personnel)
Coordinate gas lift activities with field supervisor

7. Type of Recommendations

8. Number of Wells Reviewed Monthly

9. Oil Gain Contribution by Field
Total oil gain = 3559 bopd

10. Diagnostic Tools
To optimize gas dual lift well, complete information is required:
Well Case History
Three-Pen Static Pressure Recorder
Daily Production Record
Flowing and Static Pressure Survey
Flowing and Static Temperature Survey
Echo Meter Survey
Well File (Drilling, Well Schematic)
Latest GLV Design Report
Setting Pressure Report
Wire Line Job Report

11. Well Review by Team Old Oil Field with more than 30 years old
High FGOR with 1000 : 1 or more
Low PI with only about 1 – 3 blpd / psi
Low Production with about blpd
Low Static Pressure with average ~ 600 psi
Limited Casing Pressure with ~ 600 psi only
Flowing Tubing Pressure is about 180 psi
Shallow well - reservoir depth ~ 3000 ft TVD
Limited data (SBHP and PI is normally unknown)
Old wells - may have leaking valve or tubing
Some gas lift valves installed 5-10 years ago

12. Dual Gas Lift Design – Lessons Learned
Enough Kick Off (KO) and Operating (OP) Pressure to reach deepest point of injection is required
Differential pressure between KO and OP is ~10% of casing pressure, (or at least 50psi) to cover all unloading valves of both strings are closed when surface casing pressure is set at OP
Use graphical method to select best point of injection of both strings and best draw down ( psi) of both strings
Calculate by computer setting pressure Ptro; select best port sizes and gas injection rate required
All pressure settings (Ptro) of unloading valves for both strings must be selected according to surface closing pressure
Surface closing pressure of both strings must be at least 20 psi above OP, and 10 psi less than KO
Avoid “gas robbing” - depth point of injection of both strings must be close or equal; same thing in port size

13. UXA-4S/L Well Schematic
REDESIGN WELL
Since mandrels were installed in well, optimization on this will be done by redesign.
Main job is how to determine best point of injection of both strings for optimum draw
down and to avoiding robbing.
To perform this job, gathering
complete information of both
strings is required.
Since SBHP data is old enough, and to ensure static pressure therefore SBHP survey is required to be performed.

14. UXA – 4S/L Data Data Description UXA – 4S UXA – 4L SBHP 1200 psi
PI (Predicted)
2 – 3
W / C
87 %
85 %
CHP
650 psi
FTP
200 psi
FGOR
1300 : 1
1500 : 1
B t m Temp.
170º F
178º F
Surf. Temp
100º F
C s g Size
9 –5/8 “
9 – 5/8”
T b g Size
2 – 7/8”

15. Graphical Method UXA – 4L PRESSURE (psi) 500 1000 1500 FTP CHP D E P T
FTP
CHP D E P T H Ft V
0.1 p s I / ft
Casing Pressure FL
1000 #1
Tubing
Pressure #2
2000 #3
0.45 p s i / ft #7
3000
Mid Perforation
FBHP
1200 p s i
4000

16. Existing Valve Installed
SPM #
U X A – 4S
U X A – 4L 1
Dummy 2
G l v, 1/8”, 615 #
G l v, 1/8”, 620 # 3
G l v, 1/8”, 600 #
G l v, 3/16”, 635 # 4
G l v, 3/16”, 615 #
S/O, 3/16” 5
G l v, 3/16”, 600 # 6
G l v, 3/16”, 590 # 7

17. Computer Program Results (UXA – 4L)
SPM #
VALVE
PORT
PTRO
PCS 1
GLV
1/8
595
646 2
300
OPEN 3
S/O NA 4 D 5 6 7
NOTE: Third mandrel is designed with S/O, but existing #3 valve can not be pulled out, therefore #2 valve is opening and set with Ptro = 300 psi

18. Computer Program Results (UXA – 4S)
SPM #
VALVE
PORT
PTRO
PCS 1
GLV
1/8
595
646 2
590
642 3
S/O
3/16 NA 4 D 5 6 7

19. Gain Results After Gas Lift Redesign
Gas lift valves were calibrated in workshop, then installed; unloading of tubing strings was done with at least 650 psi as KO. After well unloaded, then gas injection rate was adjusted to maintain surface casing pressure at 640 psi, or OP. Following chart summarizes results after gas lift optimization:
OPERATING PRESSURE: 640 psi
UXA – 4S
BEFORE GL OPTIMIZATION
( March 1996 )
AFTER GL OPTIMIZATION
( March 2002 )
FLUID RATE
413 BLPD
1037 BLPD
OIL RATE
79 BOPD
255 BOPD
GAS IN
864 MSCFD
250 MSCFD
GAS OUT
2448 MSCFD
550 MSCFD

20. Gain Results After Gas Lift Redesign
OPERATING PRESSURE: 640 psi
UXA – 4L
BEFORE GL OPTIMIZATION
(March 1996 )
AFTER GL OPTIMIZATION
(March 2002 )
FLUID RATE
670 BLPD
1751 BLPD
OIL RATE
97 BOPD
122 BOPD
GAS IN
621 MSCFD
120 MSCFD
GAS OUT
748 MSCFD
186 MSCFD
Well had been shut in since March 1996, and back on line March 2002 after gas lift redesign.

21. UXA Platform Results After GL Optimization (March 2002)

22. Total Oil Gains After Well Work at BP-Indonesia
NOTE: Gas lift is the biggest contributor (70%) of the well work jobs, which resulted in oil gain at NWJO; BP-Indonesia