Gas Lift Optimization
at BP-Indonesia
Dual String Gas Lift Well
With Injection Pressure Operated Valve
By: Gatut Widianoko
Weatherford Artificial Lift Systems
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 3000 - 4000 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”.
Offshore Northwest Java Oil Field
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

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
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
Type of Recommendations
25%
40%
8%
27%
Redesign
CH Adj.
Mdrl. Spac.
No. Potential
Number of Wells Reviewed
Monthly
42
37
29
32
34
25
D
ec
.
ov
.
N
ct
.
O
A
ug
.
S
ep
t.
Ju
ly
14
Ju
ne
M
ay
45
40
35
30
25
20
15
10
5
0
36
Oil Gain Contribution by Field
Total oil gain = 3559 bopd
344
638
1485
1092
Bravo
Echo
Foxtrot
Lima
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
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 200 - 500 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
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 (200-300 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
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.
UXA – 4S/L Data
Data Description
SBHP
UXA – 4S
1200 psi
UXA – 4L
*1200 psi
PI (Predicted)
W/C
CHP
FTP
2–3
87 %
650 psi
200 psi
2–3
85 %
650 psi
200 psi
FGOR
B t m Temp.
Surf. Temp
1300 : 1
170º F
100º F
1500 : 1
178º F
100º F
C s g Size
T b g Size
9 –5/8 “
2 – 7/8”
9 – 5/8”
2 – 7/8”
Graphical Method
PRESSURE (psi)
0
D
E
P
T 1000
H
500 CHP
FTP
UXA – 4L
1000
1500
0.1 p s I / ft
Casing Pressure
FL
Tubing
Pressure
#1
#2
Ft
2000
T
V
D
#3
#7
3000
Mid Perforation
4000
0.45 p s i / ft
FBHP
1200 p s i
Existing Valve Installed
U X A – 4S
U X A – 4L
1
Dummy
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 #
Dummy
6
G l v, 3/16”, 590 #
Dummy
7
S/O, 3/16”
Dummy
SPM #
Computer Program Results
(UXA – 4L)
SPM #
VALVE
PORT
PTRO
PCS
1
GLV
1/8
595
646
2
GLV
1/8
300
OPEN
3
S/O
¼
NA
NA
4
D
NA
NA
NA
5
D
NA
NA
NA
6
D
NA
NA
NA
7
D
NA
NA
NA
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
Computer Program Results (UXA – 4S)
SPM #
VALVE
PORT
PTRO
PCS
1
GLV
1/8
595
646
2
GLV
1/8
590
642
3
S/O
3/16
NA
NA
4
D
NA
NA
NA
5
D
NA
NA
NA
6
D
NA
NA
NA
7
D
NA
NA
NA
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
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.
UXA Platform Results After GL
Optimization (March 2002)
UXA P/F Production Profile
4000
3500
Production
3000
Start GL
OPtimization
2500
MCFD
2000
BOPD
1500
1000
500
0
01/03/2002
11/03/2002
21/03/2002
31/03/2002
10/04/2002
Date
20/04/2002
30/04/2002
10/05/2002
Total Oil Gains After Well Work
at BP-Indonesia
2002 Well Work - Oil Rate Projection
2002 Target Cum
2002 Actual Cum
10000
BOPD
8000
6000
4000
2000
0
Jan-02 Feb-02 Mar-02 Apr-02 Mei-02 Jun-02 Jul-02 Agust- Sep-02 Okt-02 Nop-02 Des-02
02
NOTE: Gas lift is the biggest contributor (70%) of the well
work jobs, which resulted in oil gain at NWJO; BP-Indonesia