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There are two main trains in FPSO Ichthys, each capable of handling approximately 422 m3/h or nominally 50% of the liquid production peak. Liquids reaching the FPSO though the subsea transfer line are received in the pipe slug catcher. The liquid is then divided equally between the two production trains. Each production train consists of three stages of three-phase separation: giving flash gas, condensate, and an aqueous stream.
The flash gas is compressed through a four-stage compression process. It provides gas to the FPSO, which is used by the gas turbine generators (GTG) to provide electricity to the whole facility. In the early life of the FPSO, there will be an excess of flash gas (in comparison with the needs of the GTG), and liquids from the intermediate pressure and medium pressure stages of compression will be sent back from the FPSO to the CPF via one of the flash gas subsea transfer lines.
The condensate passes through three stages of separation. The condensate vapour pressure is controlled in a heating or cooling process during the final stage so that the condensate can pass straight from the final separation stage into the FPSO reception tanks. The reception tanks provide a final separation stage for the condensate. Any remaining rich monoethylene glycol (MEG) accumulates at the bottom of the tank and can be pumped out separately before the stabilized condensate is pumped into the cargo tanks. The condensate is transferred to storage at 48°C. The cargo tanks store the condensate at high temperate (38°C to 48°C) to prevent wax from dropping out. The contents of the cargo tanks are permanently running through heat exchangers located on the topsides to regain heat lost through the walls of the cargo tanks. The aqueous stream is called rich MEG (about 50%wt MEG in water). The rich MEG passes through a MEG regeneration unit, where MEG is recovered and re-concentrated to lean MEG (about 90%wt) for re-use.
Heating and cooling requirements
The purpose of the cooling medium system is to facilitate cooling at certain stages of the process and remove excess heat generated by various items of equipment.
Closed loop re-circulating treated fresh water cooling systems is used throughout equipment packages. Cooling of the fluid medium will be via seawater system heat exchangers.
The cooling medium expansion tank shall be of sufficient capacity to provide a means of safely venting gas to flare in the event of gas cooler failure.
A heating medium system is to be provided as a heat source for use in the gas and liquid hydrocarbon processing systems.
The system shall provide for:
• A closed loop system in which a suitable heating medium is constantly circulated;
• Heating medium circulation pumps with on line spares to assure power generation performance can be maintained at all times;
• Installation of a dump cooler to dissipate heat during low process heat demands;
• A side stream filter arrangement to remove suspended particles.
The filter shall be of duplex construction to facilitate safe cleaning online. The design of the heating medium system will ensure maximum availability. There will be no single point failure mechanism within the system and all maintenance will be carried out while the system is on line.
Figure 3: 3D-exploded view of the FPSO with the area of concern
Subsea wells are located in clusters (drill centres). Fluids are transported to the central processing facility (CPF) from the various drill centres through gas-gathering systems. Each gas-collection system consists of two flowlines connecting two to three drill centres to the CPF. At the CPF, each subsea flowline is connected to the topsides flowline with its own flexible production riser.
The lean MEG (90%wt MEG in water) is injected in each well-head choke as an active hydrate inhibitor. This lean MEG injection results in the fluids arriving to the CPF being a mixture of gas condensate, hydrocarbon gas, and a water/MEG mixture (rich MEG). The lean MEG is sent subsea from the FPSO.
There are three production trains on the CPF. Each of them has a nominal capacity of 600 MMscfd. Each flowline is connected to two of the three trains, but only one train at the time will be in line during operation. In normal production, there is basic gas or liquid separation in the ISV (inlet surge vessel). At the outlet of the ISV, the gas passes thought the high-pressure separator (which allows liquid drop-out) and then passes to the dehydration inlet scrubber. The flash gas that comes back from the FPSO is injected at this stage. The gas then passes through the glycol dehydration column in which the TEG (triethylene glycol) removes the water from the gas stream. The final stage has the export compressors leading the gas to the LNG plant through the gas export pipelines. After many years of field exploitation, the operating pressure of the ISV will be reduced. A booster compression facility will be inserted between the high-pressure separator and the dehydration inlet scrubber in order to ensure the operating pressure in the glycol dehydration column.
All the liquids removed during the different stages on the CPF are transferred to the FPSO through subsea transfer lines. In order to avoid the appearance of wax, the temperature of the transferred liquid is controlled in the liquid export heat exchanger. The gas or liquid separation in the ISV depends on the arrival temperatures of the fluids at the CPF. Higher temperatures will drive more gas out of the liquid, which means a reduction of the liquid flow to the FPSO.
Condensate is transferred from CPF to FPSO via one of the two condensate transfer lines. In normal operation, only one line is used at one time. However, under certain conditions, one line is not enough to support the flow rate, and both lines are used.
Gas Export Pipeline
The dry export gas is fed from the topsides facilities of the CPF to the gas export riser base. The riser base provides a manifold connection of the four flexible risers and facilities for temporary connection of a subsea pig launcher. The gas export riser base is connected by rigid pipe to the gas export pipeline. Gas is exported via a nearly 900 km long pipeline from the CPF to the onshore LNG facilities located in Blaydin Point (Darwin, Australia). All along the pipeline, there are hot tap tees and a removable spool for future gas export pipeline tie-ins.
Figure 5: Localization of the Ichthys FPSO, CPF and the LNG facility connected by pipeline
The facilities onshore at Blaydin Point, Darwin include gas receiving, an LNG process plant (2 x 4.2 Mtpa trains), product storage, and export facilities to LNG tankers. In addition to the production of LNG for the LNG tankers, other products that are produced and exported will include LPG and condensate.
Oil and gas projects no longer have only one client. In order to minimize risk for investment, the clients are usually joint venture holdings. The Ichthys project (FPSO, CPF, pipeline, LNG plant) is financed by INPEX (76%) and Total (24%). The client is named INPEX as it invests more. In this report, the term ‘client’ will be used.
Two major facts result from this joint venture holding. The first is due to Total. Total’s philosophy, named OPERCOMTM (explained in Section 5.1), is the conception philosophy used for the Ichthys project. The second fact is that the Ichthys project is based in Australia. This leads to tougher regulations in design and commissioning.
INPEX Corporation is a global oil and gas exploration and production company headquartered in Tokyo. INPEX is involved in more than 70 projects in nearly 30 countries. In 2014, INPEX was ranked 61st in the global energy company ranking (see Platts Top 250).
Total is a global oil and gas exploration, production, and distribution company headquartered in Paris. It is involved in hundreds of projects in more than 130 countries. In 2014, Total was ranked eighth in the global energy company ranking (see Platts Top 250)
Founded only 40 years ago, the DSME yard is now one of the top shipbuilding and marine engineering companies in the world. To give an example of its strength, in 2014, DSME became the first shipbuilder to receive an order for 49 gas carriers in a single year. The 4,900,000-m2 yard employs more than 13,000 direct employees and 25,000 subcontracted production employees. The yard capacity is 55–60 commercial vessels, 16–18 offshore projects, and two to three special vessels.
From the 1970s to the current date, DSME has succeeded in major projects. DSME constructed 943 commercial ships (LNG and LPG carriers, oil tankers, full containership, etc.), and 439 offshore projects and plants (fixed platforms, FPSO, drillships, semi-submersible rigs, etc.).
Figure 6: 3D Plan of the DMSE yard
Main equipment vendors
Sulzer is an industrial engineering and manufacturing company headquartered in Winterthur (Switzerland). It is one of the world leaders in the diesel pumps market.
LHE (Plate-type Heat Exchangers)
LHE is a local SME (small and medium-sized business) based in Busan (Korea). It produces heat exchangers for the naval industry.
Alfa Laval (Heaters)
Alfa Laval is an industrial engineering and manufacturing company headquartered in Lund (Sweden). It is a world leader in heat transfer, separation, and fluid handling.
General Electric (WHRU on GTG)
General Electric is a company headquartered in Fairfield (USA). General Electric is a global leader in the energy sector.
Sub-contractor for the Commissioning
Actemium is a subsidiary of the group VINCI Energies. It is the brand dedicated to the industrial process.
The commissioning activity of Actemium focuses on the OPERCOMTM philosophy and the software ICAPS©. Actemium undertakes the following activities:
• Delimitation of the systems and sub-systems
• Planning of the task, material, and equipment
• Organization of the different teams involved in the project (sub-contractors, suppliers, certification company)
• Human resources estimation
• Commissioning and pre-commissioning management
• Population of the database in the software ICAPS©
Actemium provides commissioning on the following activities: administration and coordination ICAPS©, electricity, instrumentation, telecommunication, construction, mechanics, piping, and command control and process.
The main business sector of the commissioning activity of Actemium is the oil and gas sector (including exploration, production, refining, transport structure, compression station, and underground storage). The company is located in Europe (Norway, Spain, Italy, France, etc.), Africa (Gabon, Congo, Nigeria, etc.), the Middle East (Saudi Arabia, United Arab Emirates, etc.), Asia (Thailand, Indonesia, Korea, etc.), and America (Argentina).
DNV (Det Norske Veritas) is a Norwegian independent foundation that deals in risk management. It specializes in the evaluation and inspection of the technical conditions of naval construction. In this project, DNV is present to ensure that the engineering, construction, and commissioning is carried out safely and in the most efficient way.
Base of design
The installation is designed to produce 1,657 MMscfd (28,317 m3/day). Each day of unavailability of the installation represents a significant daily shortfall. As the FPSO is located 300 km away from the nearest point on the Australian coast, the time needed to order, transport and install specific equipment (motors, heat exchangers, etc.) could stop production for weeks. In order to prevent any such shortfall, the redundancy philosophy is more exigent than in other industries.
The security on the FPSO is another key point. Any system should be able to run at any time — even in case of equipment failure or during equipment maintenance. High pressure, high temperature, high voltage, high mechanical strain and toxic/ explosive/ flammable liquid and gas represent potential hazards. From the failure of an equipment may result consequential damages. Sparing and redundancy philosophy is thus based on these two main factors: shortfall and safety. The following are descriptions of all the equipment of heating and cooling systems, which are the subject of the sparing and redundancy philosophy. First, the sparing philosophy for each type of item present in the systems is described. Then, the sparing philosophy is explained for the instrumentation.
Note: When an item or instrument is indicated to be N+1 spared, it refers to N as the minimum number of items or instruments required for proper functioning.
Pressure drums are not susceptible to mechanical breakdown and as such do not require to be taken out of service frequently for maintenance or inspection purposes. Full field shutdowns will occur in year 1 and subsequently at 3 year intervals. The duration of full field shutdowns will vary depending on whether the shutdown is purely for inspection requirements or for planned maintenance.
Due to the requirement for total facilities shutdown to permit flare tip inspection and maintenance, most of the vessels within critical utilities systems are not spared. The cooling medium and heating medium expansion drums do not require to be spared. They will be inspected during this full facilities planned shutdown (every 3 years).
Shell & Tube Heat Exchangers
Shell and tube (S&T) heat exchangers are generally not susceptible to mechanical breakdown although appropriate protection shall be provided to safeguard equipment in the event of tube failure and cross contamination of fluids. In general, S&T heat exchangers shall not be spared and are inspected periodically.
However, the 2 x 100% heating medium exchangers (S-640-E-002-A/B) which supply heat to the secondary heating medium system are critical S&T heat exchangers. They shall be spared for productions reasons and for operation in fouling service requiring frequent maintenance for cleaning. For this reason, this heat exchanger is N+1 spared.
Air Cooled Heat Exchangers
Air cooled heat exchangers (ACHE) are susceptible to mechanical breakdown of the motor-driven fans.
Table of contents :
2 PROJECT BACKGROUND
2.1 Ichthys Project
2.2 Ichthys FPSO
2.2.1 General description
2.2.2 Heating and cooling requirements
2.3 Annex Installations
2.3.3 Gas Export Pipeline
2.3.4 LNG Plant
3 THE COMPANIES
3.3 Main equipment vendors
3.4 Sub-contractor for the Commissioning
3.5 Certification Company
4 THE INSTALLATION
4.1 Base of design
4.2 Description of the System
4.2.1 Cooling Medium System
4.2.2 Heating medium system
5 METHODOLOGY OF THE COMMISSIONING
5.1 Methodology OPERCOMTM and ICAPS©
5.2 Project Organization
5.3 Pre-commissioning Activities
5.4 “Commissioning” activities
5.5 Start-up Activities
5.6 Engineering Documents
5.7 Commissioning: Onshore and Offshore
6 HEATING AND COOLING SYSTEMS OPERATIONAL TEST PROCEDURES
6.1 General Planning
6.2 Cooling System
6.2.1 Activity completion
6.2.2 Pre-requirement of the OTP for the cooling medium system
6.2.3 Control Philosophy
6.2.4 Post-operational Test
6.3 Heating System
6.3.1 Activity completion
6.3.2 Pre-requirement of the OTP for the heating medium system
6.3.3 Control Philosophy
6.3.4 Post-operational Test