Flare practice & improvementon Gullfaks oil field

Magne BJØRKHAUG

Ph.D.Adviser, Process safety, Statoil

Statoil operations in the North sea

• 60 % of the produced oil and gas is operated by Statoil

• Gas and oil is transported through extensive pipelinesystem or through offshoretanker loading of oil

• Most new installations andsome of the old ones haveinstalled the flare gas recovery system

New flare modus implemented on Gullfaks in 1994

New flare practice on Gullfaks oil field

• One production mode - Two flare modes

Open and ignited flare Closed flare system

Basic elements in the new flare system

1. High integrity flare opening valve

2. Flare gas recovery system

3. Flare ignition system

4. High quality safety system

Basic elements in the new flare system

To the flare stack withignitionsystem

XV

HP K.O. Drum

Bursting Disc

Sources

PTHH

PTHH

LO LO

FOV

Flare gas recovery system

HIPPS

High integrity flare opening valve on Gullfaks

Ignition unit on Gullfaks C

Ignition unit

Flare practice & improvement

• Environmental and economical improvements –Reduces CO2 emission to the atmosphere–Save CO2 tax–Increase gas utilisation–Increase the lifetime of the flare tip–Reduces the need for purge gas in the flare system

Flare practice & improvement

• Operational improvement to achieve the results

–A proper designed plant control system–A proper planned plant maintenance system–Recovery of gas from depressurisation of equipment

–Recovery of blanket gas

Flare practice & improvement

• Avg. flare per year - Gullfaks C

0

50 000

100 000

150 000

200 000

1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Vo

lum

e: S

m3/

d

Flare practice & improvement

• Gullfaks C - Daily flare volume 2005

0100200300400500600700800900

01.0

1.20

05

01.0

2.20

05

01.0

3.20

05

01.0

4.20

05

01.0

5.20

05

01.0

6.20

05

01.0

7.20

05

01.0

8.20

05

01.0

9.20

05

01.1

0.20

05

01.1

1.20

05

01.1

2.20

05

1000

Sm

3

Flare practice & improvement

• Gullfaks C - Daily flare volume 2005

0100200300400500600700800900

1000

Sm

3

01.0

1.20

05

01.0

2.20

05

01.0

3.20

05

01.0

4.20

05

01.0

5.20

05

01.0

6.20

05

01.0

7.20

05

01.0

8.20

05

01.0

9.20

05

01.1

0.20

05

01.1

1.20

05

01.1

2.20

05

A continues flare load of App. 50.000 m3/day is added at the bottom

Estimates of reduced flaring

• Total flaring 2005 for Gullfaks C: 26 656 m3/day• Continues basic load: App. 50 000 m3/day• Estimated total flare load: App. 75 000 m3/day

• Estimated reduction for Gullfaks C in 2005: 60-70 %

Average reduction in yearly flaring du to the “no-flare” technology is approximately 50% on Gullfaks during normal operation

Flare practice & improvement

The system have been operated without any major problem for the operation time of 12 years.

The systems have been rebuilt to increase the capacity due to tie-in of satellite fields.

Described in 1997 version of API 521.

Total savings in 12 years has been in the order of $ 200 mill.

Gullfaks flare system 12 years after: