laggan & tormore gas plant: 18 months of operation results of a … · 2021. 3. 30. · sullom...
TRANSCRIPT
Laggan & Tormore Gas Plant: 18 Months of Operation Results of a New Produced Water Treatment
Patrick Baldoni-Andrey Total Cathy Fuchs Suez
AGENDA
• Background • Process Overview • Operating results • Conclusions
Laggan & Tormore – Shetland Gas Plant (UK)
The Shetland Gas Plant (SGP) is a 500 MMSCFD capacity gas plant located at
Sullom Voe. It receives reservoir fluids, via twin 143km multiphase flow
lines, directly from the Laggan-Tormore fields which are located 125km
north-west of the Shetland Islands (North Sea) in approximately 600m water
depth.
The produced water is fed to the Effluent Water Treatment Plant (EWTP) for
processing prior to being discharged to Yell Sound via a 3.75km pipeline. Slug
Catcher
Incoming gas
Condensates separation
Gas to processing / export
Condensates to BP Sullom Voe
MEG processing
Lean MEG to subsea production
Produced Water
SGP MEG regeneration effluent source
rich MEG
effluent
pretreatment vessel
particle filter
MEG regeneration column
side stream MEG reclamation unit
MEG reflux drum
lean MEG
brine slurry
SGP EWTP Pegasus process
effluent discharge to sea
Oil separator
•insoluble hydrocarbon removal
Stripping
•BTEX removal
•no waste product
•fuel gas reused in the LP gas system
Polishing
•residual hydrocarbon removal
•biofilter wash water treatment
Biofilter
•soluble organic removal
SGP EWTP – Deoiling since start up
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
03-2016 04-2016 05-2016 06-2016 07-2016 08-2016 09-2016 10-2016 11-2016 12-2016 01-2017 02-2017 03-2017 04-2017 05-2017 06-2017 07-2017 08-2017 09-2017
Oil
(m
g/l
)
Effluent Feed Flotation Unit Outlet
Effect of upstream improvement
Effect of temperature increase
SGP EWTP – physical BTEX removal
0
200
400
600
800
1000
1200
To
tal
BT
EX
(m
g/l
)
Feed effluent Stripping outlet
64%
26%
5% 1% 4%
Feed BTEX composition
62%
24%
9% 2% 5%
Stripped effluent BTEX composition
Benzene Toluene m- & p-Xylene Ethyl Benzene o-Xylene
No significant change in proportions of individual components Stripping equally effective for removing different BTEX components
SGP EWTP – Optimizing chemical dosing to improve TSS removal
0
20
40
60
80
100
120
140
03-2016 04-2016 05-2016 06-2016 07-2016 08-2016 09-2016 10-2016 11-2016 12-2016 01-2017 02-2017 03-2017 04-2017 05-2017 06-2017 07-2017 08-2017 09-2017
TS
S (
mg
/l)
Flotation Unit Outlet
Coagulant #1
Flocculant #1
Coagulant #1
Flocculant #2
Coagulant #1
Flocculant #3
Coagulant #2
Flocculant #3
SGP EWTP – COD reduction upstream of the biological treatment
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
03-2016 04-2016 05-2016 06-2016 07-2016 08-2016 09-2016 10-2016 11-2016 12-2016 01-2017 02-2017 03-2017 04-2017 05-2017 06-2017 07-2017 08-2017 09-2017
CO
D (
mg
/l)
Effluent Feed Flotation Unit Outlet
MEG regeneration
•Optimize operation
EWTP
•Improve chemical dosing
Biological treatment
•Less load
SGP EWTP – biological treatment performance
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
03-2
016
04-2
016
05-2
016
06-2
016
07-2
016
08-2
016
09-2
016
10-2
016
11-2
016
12-2
016
01-2
017
02-2
017
03-2
017
04-2
017
05-2
017
06-2
017
07-2
017
08-2
017
09-2
017
CO
D (
mg
/l)
COD removal
Biofilter feed Biofilter out
0
5
10
15
20
25
30
35
40
45
CO
D (
mg
/l)
Phenol removal
Biofilter feed Biofilter out
Upstream optimization
Better pretreatment
Better biological
performance
Better removal of components such as Phenol
Visual indication of performance across the EWTP
Conclusions
• First 18 months of operation have shown the importance of: • Optimizing the upstream process to control load to the effluent
treatment • Getting the chemical selection right • Maintaining stable operation of the EWTP
• Once the above issues were addressed good compliance with the plant’s discharge permit was achieved
Thank you for listening