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Subsea System Architecture for Coral South FLNG

Francesco Rossi

Gastech 2017

Eni Mozambique

Engineering

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Eni Overview

Saipemengineering & construction

Versalischemicals

30.5% 100%

Italian Government 30% Market70%

exploration & production gas & power refining & marketing

exploration upstreammidstreamgas & power

Equity holding

Retail market gas & power

Development operations & technology

Revenues 55.8 bln €

Operating profit Adj. 2.3 bln €

Capital Expenditures 9.2 bln €

2016 Highlights

Production 1.76 Mboe/d

Proved reserves 7.5 bln boe

Organic RRR 193 %

Eni Mozambique Engineering

More than 34.000 employees in 69 countries of activity

LNG Experience

Eni's LNG Business

Eni's Track Record in LNG

Global LNG presence, with significant expertise throughout the value chain.

In 2015 Eni supplied 4.2 BSCM of feedgas to LNG plants, held 10.9 BSCM of liquefaction capacity, 15.6 BSCM of regassificationcapacity and sold 13.6 BSCM equivalent of LNG.

Eni intends to significantly strengthen its position along the whole LNG chain. This growth will be driven by Mozambique and new projects in Nigeria and Indonesia, where Eni is a significant player.

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Eni Floaters Experience

4 Eni Mozambique Engineering

Floaters in Eni Operated Fields

In Operation 5 FPSO (Angola, Italy, Nigeria, Norway 2 FSO (UK, Lybia) 1 Construction Support Jack up (UK)

Under Construction 1 FPSO (Ghana) 1 FPU (Indonesia) 1 FSO (Lybia)

Under Development 1 FPSO (Nigeria) 1 FLNG (Mozambique)

Recently Decommissioned 1 FPSO (Timor Leste)

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Area 4 Location: deep offshore Mozambique @ 200 km

from Pemba

Water depth: 1,500-3,000 m

Block Awarded: December 20th 2006 to JV Partners (Eni

East Africa SpA: Operator)

Exploration and Appraisal Wells: 15 of which 4 in Coral

Development & Production Phase: 30 years from

effectiveness of Plan of Development Hydrocarbon

Type: Gas + Condensate

Mozambique Area 4 Summary

Area 4 Location

IT00537VMozambique Coast

Palma

Pemba

TANZANIA

MOZAMBIQUE

Area 4

Maputo50 km

Area 4 Overview

Area 1 Area 4

Mamba N-1

Mamba NE-2

Mamba NE-1Mamba NE-3Mamba S-3

Mamba S-1Mamba S-2

Coral-2

Coral-1

Coral-3

Coral-4DIR

Agulha-1 dir.

Agulha-2

Area 4

* Eni & CNPC hold an indirect W.I. through their participation in EEA

*

50%

20%

70%

10%

10%

10%

*

JV Partners


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Coral South Development

FLNG Facilities

Liquefaction capacity in excess of 3.3 MTPA;

APCI Dual Mixed Refrigerant (DMR);

MEG Hydrate Inhibition;

Internal Turret Mooring System, non disconnectable;

Side-by-Side Offloading;

LNG Tanks: total storage >230,000 m3

Condensate Tanks: total storage ≈ 50,000 m3

Hull Dim.: 404m L x 66m B x 39m D;

Living Quarters: 350 POB;

25 Year Design Life without Dry Dock;

Subsea Facilities

6x Subsea wells;

7” subsea X-trees;

3x cluster manifolds;

6x 10” ND flexible flowlines;

6x 9” ID flexible risers;

3x pigging loops;

3x Umbilicals.


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Geophysical & Geotechnical Site Characterization

Site characterization completed;

A site-specific PSHA* has been performed;

Design Basis are a result of Geotechnical/Geophysical Campaigns;

Final geotechnical data are available for EPCIC;

Subsea components (e.g. Wellheads, Manifolds, Flowlines, Moorings)

are located in an area not subject to Geohazard.

FEED

2014 2015 2016

Geophysical Campaign

Geotechnical - shallow

Geotechnical

Shallow Geotechnical

Reports Geohazard Reports

Preliminary Reports

Geotechnical Campaign - Deep

2013

Deep Geotechnical Reports

Ground Survey for Geohazard, Geotechnical (Deep), Slope stability;

Geotechnical Survey for Mooring Lines, Risers and Flowlines.

Coral South Development Area

*Probabilistic Seismic Hazard Assessment


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Geophysical & Geotechnical Investigations Area


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Area 4 Subsea


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Area 4 Subsea


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Area 4 Subsea


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The Subsea System

Design Life: 30 years service + wet storage

period;

Design Water Depth : 2,300m;

Seabed Temperature : 2.5°C;

Production Rate: 150 MMscf/d, per well;

6 wells clustered in pairs;

3 manifolds with integrated SDU;

3 umbilicals, one for each cluster;

6 flowlines and riser systems;

Maximum Wellhead Shut-in Pressure: 415 bar.


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Subsea Production System Architecture

Advantages: Reduced type of subsea structures;

Looped pigging of intrafield lines;

Reasonable level equipment modularization;

Redundancy in case of line damage;

Flexibility in production management;

Balanced distribution of risers across the mooring sectors;

Sound performance in terms of interferences between risers;

HR flexible jumper diameters within present manufacturing

capabilities;

Minimum expected liquid handling issues;

Maximum spare transport capacity.


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Umbilical System Configuration

Umbilical system design water depth ~ 2300m, design life ~ 30 years;

Location Metocean condition – Harsh, up to 10000yr cyclonic environmental condition;

Topside FLNG motion – large vessel offset ~ 230m (10% of water depth);

Other nearby adjacent structures such as flexible riser and moorings – Congested adjacent structures (6x

flexible risers and 20 mooring lines);

Six subsea wells controlled by three independent umbilical (two wells per cluster), each cluster is controlled

by one independent umbilical;

Umbilical departures from FLNG via pliant wave configuration, terminating at manifold;

Coral South Umbilical consist upper dynamic section and lower dynamic section;

Umbilical total lengths ranging from 5000m to 8000m.


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Control System Architecture Advantages

SDU not required if a large 4-way UTA is used;

Dedicated electrical cables to each cluster (reduced conductor

sections);

Dedicated hydraulic lines to each cluster (reduced line diameters);

Fast update rate and response both in commanded actuations and

uncontrolled ESD;

Good overall system availability (maximum of redundancy

capabilities);

Maximum level of achievable standardisation of equipment;

Minimum subsea equipment;

No infield umbilicals.


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The Selection of the Risers and Flowlines Solution

Two options were considered. The flexible riser coupled with flexible flowlines solution has been identified as the best;

All fundamental analyses have been performed – flow assurance analysis, global dynamic analyses, cross section

design/analyses, packing, transportation, installation analyses etc.;

In addition, three qualification tests have been identified.


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Advantages of the Risers and Flowlines Adopted Solution

Significant CAPEX saving;

De-Risking of the Installation Campaign schedule;

Production improvement at late field life;

No slugging issue;

Free spans on the flexible flowlines sections derisked;

No sand erosion and no flow induced vibration are

expected.


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Conclusions

Coral South Development Project started in 2012 with the Coral reservoir discovery in late 2011;

The whole Project area of operation has been interested by an extensive G&G survey;

The data acquired for the design of the subsea facilities minimised the relevant risks;

The design of the subsea facilities has been carried out with the target to optimise the FLNG

production in all the operating conditions and to have redundancy to maximise the availability of

the whole production system (FLNG, R&F, SPS and Wells).


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THANK YOU!
