CASING HEAD PRESSURE FINE CASING HEAD PRESSURE FINE TUNING inTUNING inDual String Gas Lift WellDual String Gas Lift WellWith Injection Pressure Operated ValveWith Injection Pressure Operated Valve

CASING HEAD PRESSURE FINE CASING HEAD PRESSURE FINE TUNING inTUNING inDual String Gas Lift WellDual String Gas Lift WellWith Injection Pressure Operated ValveWith Injection Pressure Operated Valve

By: Gatut Widianoko ( Weatherford )Herry Subekti ( BP – Indonesia )Wahyu Jatmiko ( BP – Indonesia )

By: Gatut Widianoko ( Weatherford )Herry Subekti ( BP – Indonesia )Wahyu Jatmiko ( BP – Indonesia )

ASME – WORK SHOP - KUALA LUMPUR 2003

Abstract

After two ( 2 ) years gas lift optimization performed with concentrated in gas lift change out, starting this year 2003, Bp -Indonesia begin to focus on Casing Head Pressure Tuning.

The first year, the gas lift optimization had made 3500 bopd oil gain, and the second year had made 4000 bopd oil gains. This year, up-to the second quarter 2003, BP had made 4500 bopd oil gains. This total gains is came from 40 % gas lift change out, and 60 % from Casing Head Pressure Tuning.

Today we are going to talk about the steps of casing head pressure tuning of the BP-Indonesia gas lift optimization on dual string gas lift well as follow :

1) Identify the gas lift well problems ;

2) Nodal analyzing to determine the well potential ;

3) Optimize point of injection of both string by gas lift change out ;

4) Perform Tuning Casing Head Pressure to optimize both string.

Offshore North West Java Oil Field

JAKARTA

BIMA

ARDJUNA

AV

AVS

AA

MX

MQ

MR

MM

MB

LL

L BZZ

B

K

U

E

F

ZU

P

0 25 50 KM

X

KLXKLY

KNA

KL

KK

APN

O

CILAMAYA

•KALIMANTAN

•SULAW

ESI

•SUMATERA

•J A V A

GG

GG Gas

Accumulation

“O” AREA POD

ARIMBI

CIREBON

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 Some gas lift header choke stuck open/close

BP Wells General Conditions

ECHO - WELLs COMPLETION DIAGRAM

NOT TO SCALE

9-5/8” Shoe @ 4285’ MD

2-7/8” SSSV @ 286’

Packer @ 3111’ MD

Packer @ 3504’

EZ-27 ( 4016’ - 4021’ ) ( 4025’ – 4031’ ) ( 4035’ – 4043’ ) ( 4050’ – 4062’ )

1050’

3032’

2-7/8” SPM 2-7/8” SPM

1012’

2625’

3007’

2-7/8” WB-1D SSD @ 3383’

2-7/8” WB-1D SSD @ 3183’

2-7/8” SSSV @ 248’

EZ-22B ( Squeezed-Off ) Packer @ 3340’

2-7/8” WB-1D SSD @ 3584’

2-7/8” WB-1D SSD @ 3100’

EZ-23 ( 3389’ - 3406’ )

EZ-24B ( 3590’ - 3609’ )

PBTD @ 4205’ MD

Packer @ 3900’

2-7/8” WB-1D SSD @ 3164’

1898’

2652’

1866’

Find CHP problems

Adjust CHP , Reduce / increase

Slowly until get best

production rate. Repeat it if

needed. Keep best this CHP as

operating pres.

Great savings of time &

efforts

Dual Completion

CHP Fine Tuning Candidates Wells( Gas Lift Optimization )

Suddenly production rate drop Suddenly the well dead Casing Head Pressure unstable Suddenly gas injection rate increase/decrease Inaccurate gas rate measure Robbing, and cause one (1) string dead or drop The well shutdown under maintenance The well shut-in while service status Gas lift Change out is being perform Suddenly Casing Head Pressure Increase Suddenly Casing Head Pressure decrease Suddenly Flowing Tubing Head Pressure increase

Casing Head Pressure TuningSteps in Dual Gas Lift well

Use graphical method to construct the well condition. Draw the static and flowing pressure gradient, etc.

Select Kick Off and best Operating pressure available.Use 90% (max) off Kick Off as Operating pressure.

Select best point of injection of both string ( close or same depth ) and operating port size (close or same size).

Use same surface opening and closing pressure for both string valve.

Perform gas lift well performance by software on each

string to determine optimum condition . Perform CHP tuning by open the Gas Lift Header Choke

and set at the kick off pressure selected. Adjusts the CHP slowly to reach the Best Surface

Operating Pressure selected. Record the Rates. Select the best rate and keep best CHP.

Graphical Method

0 500 1000

1000

1500

2000

3000

4000

DEPTH

Ft

TVD

PRESSURE (p s i)FTP CHP

1200 p s i

Casing Pressure

Echo- Wells

Mid Perforation

Tubing Pressure

#1

#2

#3

#7

0.45 p s i / ft

0.1 p s I / ft

FL

FBHP

Kick OffOperating Pres.

(To determine best Point of Injection, KO and OP)

Gas Lift Well Performance

Gas Injection Rate Vs Production Rate

Q l

Q i

Q I : Gas in Rate mscfd Q l : Prod. Rate blpd

Optimum Point

Why Do

Casing Head Pressure tuning

instead of

Gas Injection Rate Tuning ?

Gas Measurement Problems

Not each platform has a good measurement

facilities

Some Gas Measuring inaccurate

Gas Injection rate not recorded

Gas in VS CHP does not make sense

We Decided Using CHP as parameter to optimize gas injection

Adjust CHP to find a best production rate of both

String

Measure Gas In, after best CHP reached / selected

Record and keep best CHP of each Well

WHAT IS BEST CHP

Where is the existing CHP ? Is it too high ? Any un-loader valve reopen? Is the existing gas in too much ? Do We need to decrease it ? OR Is it too low ? Is the existing gas in too low ? Can the existing CHP pressure reach the

operating valve ? Do we need to Increase it ? Any actions needs to be done ?

Back to The Original Operating Pressure Design

Decreasing CHP

0 500 1000

1000

1500

2000

3000

4000

DEPTH

Ft

TVD

PRESSURE (p s i)FTP CHP

1200 p s i

Casing Pressure

Echo- Wells

Mid Perforation

Tubing Pressure

#1

#2

#3

#7

0.45 p s i / ft

0.1 p s I / ft

FL

FBHP

Kick OffBest Operating Pres.

(To determine Best Operating Pressure)

Existing CHPToo High

Increasing CHP

0 500 1000

1000

1500

2000

3000

4000

DEPTH

Ft

TVD

PRESSURE (p s i)FTP CHP

1200 p s i

Casing Pressure

Echo- Wells

Mid Perforation

Tubing Pressure

#1

#2

#3

#7

0.45 p s i / ft

0.1 p s I / ft

FL

FBHP

Kick OffOperating Pres.

(To determine Best Operating Pressure)

Existing CHPToo Low

Some Wells Sample of CHP tuning at BP-Indonesia

Gas Lift Optimization at EC-2ST well

Status CHKFTP (Psi)

BOPD BFPDW/C (%)

TOTAL GAS (Mscfd)

GLR (SCF/STB)

GL GAS (Mscfd)

CHP (psi)

Remark

Pretest 64/64" 140 691.2 768 10 552.7 719.66 551.41 580

Test 1 64/64" 140 864 960 10 548.43 571.28 546.23 560

Test 2 64/64" 140 777.6 864 10 543.6 629.17 540.3 540

Test 3 64/64" 140 972 1080 10 542.31 502.14 532.7 520

Post test 64/64" 140 950.4 1056 10 545.87 516.92 528.59 520

Oil Gains : 250 b o p d

Sample : A

Best CHP

Best CHP : 520 p s i

Some Wells Sample of CHP tuning at BP-Indonesia

Gas Lift Tuning at FFB-7

StatusCHK

1/64 inFTP (Psi)

BOPD BFPDW/C (%)

TOTAL GAS (Mscfd)

GLR (SCF/STB)

GL GAS (Mscfd)

CHP (psi)

Remark

Pre well test 72 120 216 864 75 - - - 200 Prior tuningTest 1 72 120 225 898 75 - - - 300

Test 2 72 120 231 924 75 - - - 400

Test 3 72 120 288 1152 75 - - - 440 Optimum rateTest 4 72 120 252 1008 75 - - - 460

Post well test 72 120 288 1152 75 - - - 440 After TuningGain 72

Oil Gains : 70 b o p dSample : B

Best CHP440

Some Wells Sample of CHP tuning at BP-Indonesia

Gas Lift Optimization at EF-5 well

Status CHKFTP (Psi)

BOPD BFPDW/C (%)

TOTAL GAS (Mscfd)

GLR (SCF/STB)

GL GAS (Mscfd)

CHP (psi)

Remark

Pretest 64/64" 130 1101.6 1224 10 1658 1355 650

Test 1 64/64" 130 1110.5 1233.9 10 864 700 624 630 Gas lift optimizationTest 2 64/64" 130 1145 1272 10 816 642 552 610 with GFC-200 runningTest 3 64/64" 130 1209.6 1344 10 744 615 516 590 test to measure gas inTest 4 64/64" 130 1166.4 1296 10 672 576 432 570 and gas outTest 5 64/64" 130 1123.2 1248 10 624 500 360 550

Post test 64/64" 130 1188 1320 10 720 546 504 590

Oil Gains : 80 b o p dSample : C

Best CHP

Best CHP : 590 p s i

Sample of One PlatformCHP Tuning Results

FFB- 1 15-Jul-03 610 220 468 70 85 - - - 16-Jul-03 630 220 723 110 85 40

FFB- 2L 16-Jul-03 360 120 952 190 80 - - - 17-Jul-03 340 120 1101 220 80 30

FFB- 2S 17-Jul-03 360 120 682 68 90 - - - 18-Jul-03 340 120 684 68 90 0

FFB- 3S 18-Jul-03 380 120 1284 128 90 - - - 18-Jul-03 380 120 1284 128 90 0

FFB- 6L 20-Jul-03 600 100 480 72 85 - - - 20-Jul-03 580 100 552 83 85 10

FFB- 7 19-Jul-03 200 120 864 216 75 - - - 19-Jul-03 440 120 1152 288 75 70

COMPLETE DATE

POST WELL TEST AFTER TUNINGPre-testCOMPLETE

DATE

TOTAL GAINS (Bopd)

GLR (scf/stb)

FTP (Psi)

GL GAS (Mscfd)

CHP (Psi)

WELL FLUID (Bfpd)

OIL (Bopd)

W/C (%)

FLUID (Bfpd)

OIL (Bopd)

W/C (%)

TOTAL GAS

(Mscfd)

CHP (Psi)

FTP (Psi)

* Total Gains for one platform by CHP tuning : 150 b o p d* Gas gains is not recorded* Working Days : 10 days.

Total Oil Gains by CHP Tuning YTD up to 2nd Qtr

Tuning Result As per June 30

0

500

1000

1500

2000

2500

3000

3500

Time

BO

PD

Tuning

Total Oil Gains by Gas Lift Change Out YTD up to 2nd Qtr’ 03

GLVCO Result as per June 30

0

200

400

600

800

1000

1200

1400

1600

1800

2000

04/0

1/20

03

11/0

1/20

03

18/0

1/20

03

25/0

1/20

03

01/0

2/20

03

08/0

2/20

03

15/0

2/20

03

22/0

2/20

03

01/0

3/20

03

08/0

3/20

03

15/0

3/20

03

22/0

3/20

03

29/0

3/20

03

05/0

4/20

03

12/0

4/20

03

19/0

4/20

03

26/0

4/20

03

03/0

5/20

03

10/0

5/20

03

17/0

5/20

03

24/0

5/20

03

31/0

5/20

03

07/0

6/20

03

14/0

6/20

03

21/0

6/20

03

28/0

6/20

03

Time

BO

PD

GLVCO

Total Oil Gains After Gas Lift Optimization YTD up to 2nd Qtr’ 03

GL Optimization Result

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

04/0

1/20

03

11/0

1/20

03

18/0

1/20

03

25/0

1/20

03

01/0

2/20

03

08/0

2/20

03

15/0

2/20

03

22/0

2/20

03

01/0

3/20

03

08/0

3/20

03

15/0

3/20

03

22/0

3/20

03

29/0

3/20

03

05/0

4/20

03

12/0

4/20

03

19/0

4/20

03

26/0

4/20

03

03/0

5/20

03

10/0

5/20

03

17/0

5/20

03

24/0

5/20

03

31/0

5/20

03

07/0

6/20

03

14/0

6/20

03

21/0

6/20

03

28/0

6/20

03

Time

BO

PD Tuning

GLVCO

Tuning Results VS Gas Lift Change Out Results up to 2nd Qtr’ 03

Tuning vs GLVCO

0

500

1000

1500

2000

2500

3000

3500

Time

BO

PD GLVCO

Tuning

Well Work Percentage

46%

9%3%23%

19%

Total Wells analyzes : 190 wells

Completed by Wire line : 31 wells

: 87 Wells potential

: 18 Wells had optimum

: 5 New wells

: 44 Wells CHP Tuning

: 36 Wells Needs FGS & SBHP survey

TOTAL GAS LIFT JOB YTD UP TO 2nd Qtr’ 03

Total Oil Gains After Gas Lift Optimization YTD Up to 2nd Qtr’ 03

5703 9942

4815

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

5500

6000

Pre-test, bopd Post-test, bopd Gain, bopd

CHP Tuning – Lessons Learned ( With Injection Pressure Valve )

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).

Use graphical method to select best point of injection and best draw down of both (200 – 500 psi) strings.

Surface opening pressure of both string are same. Use at least 10 psi less than the CHP available.

Surface closing pressure of both strings must be at least 20 psi above OP, and 30 psi less than KO

To avoid “gas robbing” - depth point of injection of both strings must be close or equal; same thing in the port size

Perform CHP tuning to reach Optimum Conditions Watch the CHP performance and Keep it at best CHP.