Contrasting Architectures, Technology Drivers and Commercialization Challenges

1. www.advisian.com
FLNG Offshore
and Nearshore
Contrasting Architectures, Technology
Drivers and Commercialization Challenges
Joe Verghese
April 2016

2. Offshore FLNG Development
Key Features:
Offshore gas field LNG FPSO LNG
Transportation
Onshore LNG
Receiving and Storage
Subsea Wells LNG FPSO LNGC LNG Storage Gas Markets
> > >
FEED gas is sourced from offshore subsea wells and subsea
gathering system.
The FLNG unit can be located in challenging deepwater
terrains.
Operational threats to topsides process performance arise from
subsea flow assurance issues (reception of slugs, pulsating gas flow).
Severity of metocean can impact topsides performance
and deliverability.

3. Atshore Deployment
FEED Gas Source Trestle and Jetty FLNG Barge Onshore LNG
Receiving and Storage
Interstate/intrastate
grid Barge
LNGC
LNG Storage Gas Markets
> > >
Key Features:
The FLNG unit is moored atshore or portside in protected
waters, against a jetty or wharf.
FEED gas (e.g. shale gas) is sourced from the grid and
meets pipeline transportation specifications.
Since the FEED gas is pre- conditioned, this minimizes
pre-liquefaction gas treatment.
The benign metocean atshore drives lower liquefaction equipment
margins and simplifies storage and offloading technology selection.

4. Probable locations for atshore
deployment are off the coast of
US and Canada, in a proximity of
interstate/intrastate pipeline grids

5. Inshore Deployment
Advisian / 5
Spur Line LNG FPSO S2S Offloading to LNGC Onshore LNG
Receiving and Storage
Interstate/intrastate
grid
LNGC
LNG FPSO
LNG Storage Gas Markets
> > >
Spur Line
Key Features:
The FLNG unit is located in inshore waters, typically a few kilometres
from shore. Several reasons drive selection of this configuration:
• Poor or unstable bathymetry at the shore line
• Significant dredging operations to cut and maintain the channel for
arriving LNG carriers
• 15 metres keel depth required at the jetty location

6. 2 feasible considerations:
Offshore jetty arrangement (or optionally an
artificial island) mooring both the FLNG unit
and the LNGC
Or
A seabed moored FLNG vessel (shown above),
with product offloading to LNG trade carriers in
a side by side configuration

7. Topsides Configuration & Building Blocks
Inlet Gas
Facilities
Solvent
Regen
Gas Treating
Regen
Dehydration
LPG/Cond
Off-loading
LPG/C5+
Storage
LPG
Extraction
LNG Storage
Liquefaction
LNG Off-
loading
UtilitiesUtilities
H20
To ships
To ships
C3/C4’s Condensate
Dry gas
FEED Gas Preparation LNG Liquefaction

8. How is process performance
differentiated between atshore,
inshore and remote offshore
deployments?

9. Atshore and Inshore FLNG
• Pre-conditioning of gas for pipeline grid transport does
not eliminate FEED gas treatment steps required on the
FLNG unit
• Very stringent CO2 (max 50 ppm), moisture (1 ppm) and
BTEX removal specifications will require installation of
associated removal units
• CO2 specification of pipeline gas (typically 2% max)
limits duty and size of AGRU regenerator system
Offshore FLNG
• Front-end treatment must be resilient to contaminants in
raw gas received from subsea wells
• Enhanced motion characteristics in this environment will
require application of greater design margins to assure
performance
• Adverse impact on weight, footprint and overall
availability
Topsides Configuration & Building Blocks

10. Advisian / 10
Feature Offshore FLNG Atshore FLNG Inshore FLNG
Feedstock Subsea Production (raw gas)
Pipeline Specification
Conditioned Gas
Pipeline Specification
Conditioned Gas
Upstream Architecture Subsea gathering system Interstate and intra-state grid Interstate and Intra-state grid
FLNG Substructure Shipshape (FPSO) Barge Shipshape (FPSO)
FEED Gas Treatment
Requirement
Acid gas removal, dehydration,
HG removal required
Required, but to a lower duty
specification due to gas pre-
conditioning and benign motions
Required, but to a lower duty
specification due to gas pre-
conditioning and moderately
benign motions.
Feed Gas Pre-treatment On FPSO On barge or (optionally) onshore On FPSO
LNG Liquefaction On FPSO On barge On FPSO
FLNG Liquefaction
Cycles FEED Matured
Turbo-expander, SMR and DMR Turbo-expander, SMR and DMR Turbo-expander, SMR and DMR
Concept/system differences

11. Advisian / 11
Feature Offshore FLNG Atshore FLNG Inshore FLNG
MCHE
PFHEs are robust, SWHE’s require
enhancement for structural
integrity and performance.
PFHEs are robust, SWHE’s require
enhancement for mechanical integrity
and performance.
Higher system integrity due
to benign motions.
PFHEs robust, SWHE’s require
enhancement.
Higher system integrity due
to benign motions.
AGRU Columns and
Scrub Column
Significant design margins
required to ensure on-spec
performance, avoidance of
channeling, etc. arising from
FPSO motion envelope.
Lower design margins required due to
benign motions.
Lower duty specifications for columns
arising from gas pre-conditioning to
pipeline specification.
Lower design margins required due to
benign motions.
Lower duty specifications for columns
arising from gas pre-conditioning to
pipeline specification.
Cooling Medium Typically Seawater Cooling.
IFC and World Bank guidelines limit
seawater temperature rise at discharge.
Could require adoption of air-cooling.
Depending on inshore location, same
concern as with atshore seawater
discharge temperature could apply.
Power Supply Generation on FPSO.
Power supply, if reliable, can be
arranged from onshore grid.
Usually generation on FPSO.
Grid power supply by subsea cable
possible.
Main Control Room
and LQ
Required on-board FPSO. Possible onshore in proximity of jetty. On-board FPSO.
LNG and LPG Storage
IHI Prismatic or Twin Row
Membrane (driven by
prevailing metocean).
Twin Row Membrane (standard
membrane tanks may be feasible).
Twin Row Membrane or IHI Prismatic.
LNG Offloading
Side-to-Side offloading with
loading arms or cryogenic hose.
Jetty-based loading arm.
Loading arms for inshore jetty or
side-to-side offloading.
Concept/system differences

12. Conclusions

13. Atshore FLNG represents the
lowest level of technical
complexity and project risk,
followed by the inshore based FLNG
Advisian / 13
Technical
Complexity
Project
Risk
Capital
Expenditure
Commercialization

14. Offshore FLNG represents
higher technical complexity,
with elevated project and
operational risk
This can arise from:
• Marrying of the subsea architecture with the FLNG
• Raw gas as the feedstock for offshore FLNG instead of pipeline
conditioned gas for atshore/ inshore FLNG
• The more hostile metocean conditions, leading to potential
impairment to performance of topsides systems (fractionators,
exchangers, etc.)
Technical
Complexity
Project
Risk
Capital
Expenditure
Commercialization

15. Cost indications
Atshore
FLNG proponents have claimed unit costs of circa 600 USD/tonne
per annum of LNG capacity.
Offshore
FLNG 1100 to 1500+ USD/tonne per annum (depending on inclusion
of costs of the subsea system).
Inshore
The unit technical cost for FLNG is expected to fall in between the
atshore and the offshore FLNG cost indications.

16. Visit our website:
http://www.advisian.com/our-sectors/hydrocarbons
Contact:
Joe Verghese
Director – Hydrocarbons
E: joe.verghese@advisian.com
Find out more

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