Coalescer.pdf

Classification: Statoil Internal Status: Draft

Erfaringer med Compact Electrostatic Coalescer (CEC)

Felttesting på Glitne

Einar Eng Johnsen, Statoils forskningssenter, Trondheim

Separasjonsteknologi 2007, Sola, 26. september 2007

2

Outline of presentation

•What is electrostatic coalescers; principles; what do we gain?

•Project history (CEC) – from 1993 till today

•Glitne: Find, fluid characterisation, laboratory and flow loop tests,

installation of CEC on Petrojarl I

•Test of CEC at Glitne – conditions, results, experiences

•Summary, conclusions

3

How does electrostatic coalescers work?

•Droplets become polarized and are attracted to each other

• In AC fields small droplets vibrate and move, causing collisions

•Emulsifying films are distorted and weaken

•Smaller water droplets coalesce into large droplets

•Promotes faster settling or separation of water from oil

•Coalescence rate is dependent on flow conditions (turbulence)

4

Typical flow schematics for CEC system

< 30-40%WC

WELL

STREAM

GAS

OIL

TO

EXPORT

2-PHASE or3-PHASE

SEPARATOR

OIL/WATER

SEPARATOR

CEC

LC

LC

PC

WATER

< 30-40%WC

GAS BLEED

< 0.5 % WC

5

Why compact electrostatic coalescers?

Conventional electrostatic coalescers:

The largest vessels in the process facilities

Compact electrostatic coalescers:

Inline droplet growth + small gravity vessel

6

CEC™ Technology History

1980’s

1993

1996

1997

1998

2000

2000

2001

2002

Time

Research at

University of

Southampton

Cooperation

with Statoil

and BP

KPS joined

as

commercial

partner

Onshore

testing

KPS

(Calgary)

Feasibility

study for

Statoil’s

Yme field

Onshore

testing

Multi Phase

Flow Loop

Norsk Hydro

(Porsgrunn,

Norway)

FIRST

Offshore Pilot at

PGS

Production’s

“Petrojarl I”,

Statoil’s

Glitne field

Demo2000

JIP for

subsea

applications

Topside

JIP

expanded

with more

oil

companies

Statoil

BP KPSUoS

Norsk Hydro

ChevronTexaco

Glitne licence,

(Statoil & PGS)

• Commercial rights was transferred from Statoil to KPS

after successful product qualification.

• STATOIL is owner of the technology.

Photo: Øyvind Hagen, Statoil

2005

Installation on:

Chevron Captain

Marathon

Alvheim

Technology

maturity

7

Principle sketch:

High voltage

electrodes coatedon both sides

Ground: Bare

steel plates

CECTM internals

•Turbulent flow combined with electric field

•Adjustable field strength

•Drop diameter growth:> 10 times

•Settling tank downstream

8

Glitne field development• Stand-alone development of marginal oil field in the Sleipner area

• 32 °API oil, asphalthenes 1.8 wt-%, water salinity 7.5%

• Contract awarded to PGS in 2000 for offshore production with Petrojarl 1 FPSO

• Focus on oil quality - modifications in the separation train

• Process consists of both conventional coalescer and a pilot CEC

• First oil in August 2001.

Oil production 7080 Sm3/d April 2002; 1340 Sm3/d September 2007

• Water production started April 2002; 8350 Sm3/d September 2007

9

Emulsion characterization of Glitne crude

• Laboratory tests prior to selection of

production concept showed

� very stable emulsions without

addition of demulsifier

� slow foam decay

• New samples taken after start-up show

similar results, but:

� different results from different samples

High pressure separation rig

0 2 4 6 8 10 12

Time, min.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

% water separated

50% WC

20% WC

Glitne separation, no demulsifier

Separator: 3 bar, 60C

P res s ure drop: 12 bar

Oil bubble point: 4 bar, 60 C

Water bubble point: 4 bar, 60 C

0 2 4 6 8 10 12

Time, min.

0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

100.0

% W

ater separated

20% WC

10% WC

Glitne separation with 50ppm demulsifier

S e pa ra tor: 3 ba r, 60C

P re s s ure drop: 12 ba r

O il bubble point: 4 ba r, 60 C

Wa te r bubble point: 4 ba r, 60 C

0 20 40 60 80 100 120 140

seconds

0

50

100

150

200

250

300

350

volume, ml

Foam decay, glitne crude oil

Crude bubble point: 4 bar, 60 C

Separator conditions : 1 bar, 60 C

Watercut: 10 %

Pres s uredrop: 14 bar

50 ppm demuls ifier

10

Onshore testing with Glitne crudeGravity Separator Oil Outlet Quality

as function of time and CEC ON vs OFF

0,0

2,0

4,0

6,0

8,0

10,0

12,0

14,0

16,0

18,0

20,0

08:24 09:00 09:36 10:12 10:48 11:24 12:00

Point of time

Outlet Oil Quality - W

iO [vol-%]

Statoil's Glitne crude oil

20% Inlet Watercut

No chemicals

Top ~70 oC

Pop ~5,5 bar g

~4 min separator oil residence

time

Time: Description:

Up to ~10.10: CEC ON

From ~10.10: CEC OFF

From ~11.40: Very unstable

loop

conditions

Test ref. B9-10

11

Compact coalescer at Glitne

Nominal flow capacity: 65000 bpd (10330 m3/d)

12

Glitne processPRODUCER

218 bar

1st stage

separator

Test separator

2nd stage

separator

Conventional electrostatic coalescer

CEC

Crude to storage

14 barg

1 bargFROM

2nd

STAGE

SEP.

CENTRIFUGAL

PUMPS

COMPACT

ELECTROSTATIC

COALESCER

OIL/WATER SEPARATOR AND/OR

UP-FLOW ELECTROSTATIC COALESCER

TO LP FLARE

TO CARGO

TO EFFLUENT

WATER

S2

S4 S6

S5

S1

S3

CEC OFF

CEC ON

SP3

SP3

Visualisation of results

CEC OFF

CEC ON

SP3SP3SP3SP3

SP3SP3SP3SP3


13

Sampling point S3

S3

14

Glitne - Oil quality downstream CEC

CEC OFF

CEC ON

SP3

SP3


CEC OFF

CEC ON

SP3SP3SP3SP3

SP3SP3SP3SP3


Glitne CEC™ Unit test

Proof of droplet growth in CEC™ Unit

0

1

2

3

4

5

6

7

8

9

10

11

12

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Inlet WC to CEC (SP2) [vol-%]

WC in the middle of CEC outlet piping (SP3) [vol-%] CEC ON Nov02

CEC ON Feb03

CEC OFF Nov02

CEC OFF Feb03

Linear

15

Oil quality downstream settling tank (trad. coalescer)

•Tests without voltage on in traditional coalescer:

Always < 0.3 % BS&W for all tested water cuts (1-21 %)


CEC™ Unit

OIL/WATER SEPARATOR

TO LP FLARE

TO CRUDE

COOLERS &

EXPORT

TO

EFFLUENT

WATER

S2

S4


CEC™ Unit

OIL/WATER SEPARATOR

TO LP FLARE

TO CRUDE

COOLERS &

EXPORT

TO

EFFLUENT

WATER

CEC™ Unit

OIL/WATER SEPARATOR

TO LP FLARE

TO CRUDE

COOLERS &

EXPORT

TO

EFFLUENT

WATER

CEC™ Unit

OIL/WATER SEPARATOR

TO LP FLARE

TO CRUDE

COOLERS &

EXPORT

TO

EFFLUENT

WATER

CEC™ Unit

OIL/WATER SEPARATOR

TO LP FLARE

TO CRUDE

COOLERS &

EXPORT

TO

EFFLUENT

WATER

S2

S4

0,0

0,1

0,2

0,3

0,4

0,5

0,6

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

CEC Inlet WC (S2) [vol-%]

Oil quality from separator [vol %] CEC 'run alone' - S4

Requirement: < 0.3 % wio

16

GLITNE COALESCER TEST, WEEK 28/2002

Coalescer inlet & outlet watercut as function of time

Coalescers ON/OFF & CEC with coated el

-20

-15

-10

-5

0

5

10

15

20

00:00 04:48 09:36 14:24 19:12 00:00 04:48 09:36 14:24 19:12 00:00 04:48 09:36 14:24 19:12 00:00 04:48

Point of time

Inlet WIO [vol-%]

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

Coalescer Inlet WC

Coalescer outlet WC

2 per. Mov. Avg. (Coalescer Inlet WC)

Outlet W

IO [vol-%

]WiO inlet/outlet of CEC

17

Field tests 2006New adjustable power supply from Magtech

•Robustness short circuits

•Dynamics, speed

•Easy to install sub-sea

WELL

STREAM

GAS

OIL

TO EXPORT

< 0.3 % wio

2-PHASE or

3-PHASESEPARATOR

OIL/WATER

SEPARATORCECTM unit

WATER

GAS BLEED

18

Field test June 2006

• New voltage controller from

Magtech to be tested

• Comparison with Variac

– No difference in oil quality

• Short circuiting much less

frequent with new voltage

controller0.00

0.50

1.00

1.50

2.00

2.50

3.00

0 1000 2000 3000 4000 5000 6000

UcecHV (Vrms)

WiO (%)

19

Inlet water cut and outlet BS&W vs timeBased on daily reports

20

Summary

•Compact electrostatic coalescer (CEC) has been working on Glitne,

Petrojarl since 2002

•With all tested water cuts (< 21 %) there is less than 0.3 % BS&W

•Combined with the secondary coalescer there is less than 0.2 % BS&W

•Combined with active voltage controller optimum performance with

regard to oil quality and maintenance can be obtained

In general:

•Large potential for weight reductions and/or process optimzation by

applying CEC

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