Adi Al Naamani and Harith Al Naabi PDO 2004 Spring Gaslift workshop Houston - 10 & 11 February 2004...

Adi Al Naamani and Harith Al Naabi PDO2004 Spring Gaslift workshop Houston - 10 & 11 February 2004

Petroleum Development Oman

Gaslift Management in PDO

Gaslift Management in PDONorthern Directorate

By Adi Al Naamani

Harith Al Naabi

1




• Introduction

• Designs, Improvements, Opportunities and challenges

• Gaslift management and processes

• Automatic Validation Tester (AVT) and Wireless gaslift trial

• Overview per area and examples

• Conclusion

Gaslift Management in PDO Agenda

2




Location

• Country size 312,000 km2

• Population 2.3 million

• Accelerated development

• 75 % income depends on hydrocarbon

IRANIRAQ

Eygpt

Sudan

Libya Saudi Arabia

Turkey

3




People

4




People

5




Beaches & Wadis

6




MUSCAT

Sur

Sohar

Salalah

ARABIAN SEA

GULF OF OMAN

100 km

• PDO (since ‘66) is a JV between60 % Government of Oman34 % Shell4 % TotalFina2 % Partex

• Shell is technical advisor

Production 700 kb/d (90% of Oman’s

Oil production)

66 producing stations

117 oil producing fields

Over 3000 active wells

620 gaslift strings. 28% of production,

200,000 bbl/d

85% of gaslift production from North

Majority of fields under water flood


7

N

S




Gaslift wells in the Northern Directorate

• The North of PDO has primarily carbonate reservoirs with depths varying from as shallow as 800m to 2700m deep.

• Now there are approximately 500 Gaslift wells constituting 50% of the oil producers.

• In the North, Gaslift wells produce 45% of the oil and 42% of the gross.

8




Design

• Design in most wells has 2 to 5 mandrels, depending on well depth and expected deepest operating point

• IPO valves are run in >95% of the wells

• Mostly unloading valve sizes are the same as the orifice valve size.

• Redesigns are done where well behaviour becomes too unstable, parameters change

9




Initial Performance

Operating @ mandrel 2 (through

unloading valve)

Later Performance

Operating @ mandrel 4

Future Performance

after on-stream of Water Injector

Operating @ mandrel 3 (through

unloading valve)

10




Optimisation and Challenges

• Well by Well– Unstable wells– Leaking valves or tubing– Well integrity (e.g. leaking casing)– Possibility to lift deeper– Scale clean outs

• Group optimisation– Surface controlled gaslift rates through SCADA / DCS– Set-points based on optimal distribution of liftgas using WinGLUE– Deferment reduction through re-distribution of liftgas

11




• Challenges w.r.t. optimal distribution of liftgas– Measurements (especially gas) are of insufficient quality. Flowing

surveys are therefore essential – Well integrity problems has Impact on well models– Continuous changes in the reservoir pressure, PI, water cut etc. – The dynamics of reservoir not captured in well models. – Young & bright, but in-experienced production engineers.

• Solutions– Dedicated production engineers on well integrity– Surveillance engineers responsible for only 50 - 70 wells in total– Intensive training and bringing in coaches

Optimisation and Challenges

12




Process

• Dedicated gaslift process– Monitor and trouble shoot using SCADA and test data– Understand the problem and correct– Further investigation– Analyse results of investigation– Determine improvement potential, costs and justify activity. – Design new gaslift string and schedule activity– Set valves, test valves before running & test retrieved valves with AVT

tester and feedback– Kick off the well and evaluate the results– Review and file report

13




PDO Gaslift Management Set-up

Gaslift Control

Gaslift Metering

Reservoir Data

Well Data

Production Data

Tubing pressure

Casing pressure

SCADA

SGAS-CAODirect monitoring

& Control of Individual Wells

DCSControls Gaslift rates to the wells

WinGLUEGaslift optimisation

Software

14




• WinGLUE gaslift QC database set up

• Automated links

• Central storage of gaslift analyses

• Most wells available in the SCADA system (RTAP / SOFS or the latest PC based FIELDWARE).

• AVT tester is used for QC valves before running and recently pulled valves

Process Improvements

15




• Implemented in the well services workshop

• TROP, stem travel, R ratio etc.

• Rejected at agreed tolerances, e.g. TROP difference < 15 PSI

• >25% of the valves were rejected on TROP.

• Visible improvements

• Testing of pulled valves just started. >60% fail on leaking bellows.

• Keep track of a “problem log” to increase understanding

• Network connection is essential

• Staff in the well services more conscious

Decker’s Automatic Validation Tester (AVT )

16




Specific Overview per AreaArea A

• Constrained due to flaring restriction (no compressor ullage)• Workshop was organised • Deliverables of the workshop:

– Coaching / training – Saving of 3.6 million scf/d of liftgas– Well integrity problems found and repaired– Detailed gaslift surveillance was carried out and many wells were stabilised– Many gaslift measurements wrong and corrected– For 2003 the estimated impact on production is approximately around 1200

bbl/d.

17 L




Specific Overview per AreaArea B

• In Area B, test data quality is an issue

• Some wells were found quit

• Some wells found with scale obstruction. Cleaned out and restored.

• Total increase in the Area B was 600 bbl/d or 10% of the total gaslift production. 3% 2002 & 2003 year average impact.

18 Q




Well was tested 2000 bbl/d net oil, low BSW

through 3 1/2”

Tubing upsize was expected to double production

Flowing survey could only be matched with 1200 bbl/d and tubing upsize was canceled

Theoretical pressures

Actual pressures

Example of importance of F/S

200 bbl/d gain from switching on gaslift

19




Specific Overview per AreaArea C

• Area C consists of two large fields

• Field N has mostly natural producers. – Flow limited by Gas Oil Gravity Drainage (GOGD)

– N compressors are full. Cutting back liftgas investigated.

• Field C is partly water-flood and partly GOGD

• Workshop held. Opportunities found:– Reduce liftgas consumption to free up compressor space (cutting

back lift-gas, running velocity strings, 3 1/2” to 2 7/8” tubing) – Some wells without RTU’s

20 F




Wireless Gaslift Valves Trial Area C

• Wireless gaslift valves (2) were installed in a well in Field C in 2002.

• Communication through a modem with PC in CCR and Main Office

• Down-hole pressures and temperatures displayed

• Full control from the desktop was achieved

• Live optimisation

• Modem on bottom valve broke down, but still operating.

• Confirmed bad batch of modems (50%)

21 F




Wireless Gaslift Valves Trial Area C

• Business case for large scale implementation being made, but– 15 - 20 times higher costs than conventional gaslift– Even with one third of costs, large scale implementation means 16,000

bbl/d extra production is required or 8% of production.

• Most promising to replace PPO valves & IPO running it as part of new well or existing well work-overs.

22 F




Specific Overview per AreaArea D

• Advanced automation; surface control valves linked to the DCS & SCADA. Full control and optimisation.

• Main challenge is well integrity and continuously changing well performance.

• Additional people have been put on the job in Area D (surveillance engineers). They complement the work of the other production engineers.

• Coaches brought in

23 Y




Specific Overview per AreaArea D - Well Examples

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

25-Apr 25-Apr 25-Apr 25-Apr 25-Apr 25-Apr 25-Apr

Tubing Pressure Casing Pressure

0

1000

2000

3000

4000

5000

6000

28-May 28-May 28-May 28-May 28-May 28-May 28-May 28-May


0

100

200

300

400

500

600

700

Mar

-03

Mar

-03

Apr-0

3

Apr-0

3

Apr-0

3

Apr-0

3

Apr-0

3

May

-03

May

-03

May

-03

Gross m3/d Net m3/d Gas Lift x 100 m3/d

Surging pressurebefore Optimisation

Stable operation

after Optimisation

Maintain Productionwith 50% less Liftgas

24Y




Specific Overview per AreaArea D - Well Examples

0

1000

2000

3000

4000

5000

6000

7000

22-Sep 22-Sep 22-Sep 22-Sep 22-Sep 22-Sep 22-Sep 22-Sep


0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

28-May 28-May 28-May 28-May 28-May

28-May 28-May 28-May


0

50

100

150

200

250

300

350

400

450

500

Jan-

03

Jan-

03

Jan-

03

Jan-

03

Jan-

03

Feb-0

3

Feb-0

3

Feb-0

3

Feb-0

3

Mar

-03

Mar

-03

Mar

-03

Mar

-03

Apr-0

3

Gross m3/d Net m3/d Gas Lift x 100 m3/d

Surging pressure

before Optimisation

Stable operation

after Optimisation

Production increase

of 350%.

25 Y




Conclusion

• Reduction in Liftgas usage (~36 mln scf/d)

• Cost savings on Gaslift compressor requirements.

• Enabled production of high GOR wells

• Create compressor capacity to handle new oil producers.

• Stabilising wells, Reduce flaring

• In some cases lifting deeper

• Sum of the measurable initial production increases after activities in 2003 is around 4500 bbl/d (2% of total North) Year average value is 0.7%.

26




What is happening next …..?

• Further enhance staff competence and skills

• Complete implementation of the AVT tester

• Trial new technology such as Bubble breaker, Bubble gaslift and surface controlled gaslift valves

• Bringing in a dedicated production engineer for gaslift

• Continue with the efforts, because it pays back.

27

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Adi Al Naamani and Harith Al Naabi PDO 2004 Spring Gaslift workshop Houston - 10 & 11 February 2004...

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