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The A18 PlatformIn May 2014, Petrogas E&P Netherlands awarded the EPCI Contract for the A18 Platform to HSM Offshore. HSM Offshore then contracted Iv-Oil & Gas as the Engineering partner in this project. Iv-Oil & Gas will also perform the Procurement Services for the A18 Platform. The shop drawings will be produced by Iv-Consult on behalf of Iv-Oil & Gas. HSM Offshore is responsible for the Construction and Installation of the platform.
Oil & Gas
Shallow Gas
The A & B Blocks in the Dutch section of the North Sea (among
others A12, A18 & B13) are located approximately 300 kilometres
from Den Helder (the Netherlands). These blocks contain
considerable volumes of low pressure (30-60 bar), almost pure
methane gas at relatively shallow depths (245-750 metres). The A12
and B13 fields have been in production since December 2007 and
December 2011 respectively.
For a long period of time, it was rendered not economically viable
to develop these shallow gas fields. Although the drilling costs
are lower due to the shallowness of the field, more compressor
capacity is needed in order to be able to transport the gas to shore.
Additionally, the shallow gas fields, or ‘marginal fields’, are smaller
than the fields located much deeper in the earth. As a result, the
total production of the shallow fields is less than that of the deeper
fields.
Over the last few years, several technical developments have led to
a cost reduction in the development of shallow gas fields. The Dutch
government has also introduced various arrangements to stimulate
the development of these fields. Furthermore, the gas price has
increased over the years. This all contributes to the improved
economic profitability of developing the shallow gas fields.
A18 Platform
The A18 Production Platform is designed to function as a Normally
Unmanned Installation. In the first phase, the platform will be
manned to perform the hook-up, commissioning and the start-up.
As soon as the platform achieves stable production, the facility
will be de-manned and thereafter visited three days a month for
maintenance and operational activities. The platform is accessible
by helicopter.
The Living Quarters will be designed for eight people. This will
be fully utilised during the first phase described above. During
unmanned operation, the platform will be remotely controlled
from the A12 Platform. If the platform is manned, it can also be
controlled from the A18 Platform Control Room.
The design of the A18 Platform has multiple similarities with
the design of the B13 Platform. The B13 Platform was designed
by Iv-Oil & Gas in 2008-2009. In particular the composition of
the gas, the pressure and production capacity of both fields are
comparable.
Process Facilities
The A18 Platform is an under construction Gas Production
Platform. It will be located on top of a shallow gas field. The
pressure in the reservoir is relatively low and the gas is very
clean. The latter is advantageous in that minimum process
equipment is necessary. The produced gas will be sent to the
A12 Platform through a 33 kilometre long pipeline, where the
gas will be treated before it is exported to shore.
Initially, three wells will be connected on the platform with an
option for a future well. The gas coming from the different wells
will be collected in the production manifold. The wells will be
checked for sand production on a regular basis by routing the
gas per individual well through a test filter. In order to prevent
hydrates from forming in the pipeline, methanol can be injected
into the pipeline before it is produced for the A12 Platform.
Hydrates (crystallisation of water with other compounds) can
build up as a result of the cooling of the gas in the pipeline
during operation. This can cause blocking in the pipeline.
A small amount of the gas will be used by the Fuel Gas
Conditioning Skid. This will condition the gas to prepare it as
fuel for the microturbines on the platform. These will each
generate 65 kilowatts of electricity, which will be used for the
main power supply of the A18 Platform.
The platform is also equipped with a Sphere Launcher, which
is used for the cleaning and inspection of the pipeline. On
a regular basis, a sphere will be launched into the pipeline
towards the A12 Platform. The sphere will be pushed by gas
pressure to the A12 Platform and will remove fluids and sand
with it. On the A12 Platform, the sphere will enter the Sphere
Receiver.
The jacket and topside are designed such that minimal
maintenance is required. The production and utility processes
are designed to minimise the environmental impact.
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A12-CPP
The A12 Platform is the Central Process Platform (CPP) where the
gas streams of the A12 Platform, B13 Platform and soon the
A18 Platform will be gathered and compressed to export pressure .
This gas is then injected into the NOGAT Pipeline to shore. In 2005
and 2006, Iv-Oil & Gas was closely involved in the engineering of the
A12-CPP.
The purpose of the A18 Platform is to guarantee the continuity of
gas flow to the A12-CPP via the tie-in to the existing production
system.
Challenges
Iv-Oil & Gas has faced some technical challenges in this project.
First, it is a short track project, which means that the engineering,
procurement activities, implementation of vendor Information
and construction are performed almost in parallel. Iv-Oil & Gas has
executed the B13 project with a level of high client satisfaction.
Iv-Oil & Gas wants to achieve the same level for the A18 Project.
Planning
In May 2014, Iv-Oil & Gas’ multidisciplinary project team started with
the engineering of the A18 Platform. The design is expected to be
finished in May 2015. In November 2014, HSM Offshore started with
the prefabrication and construction of the platform.
The Sail Away is currently planned for August 2015. After the
installation and commissioning period, First Gas, by completing
the first well, is scheduled for the fourth quarter of 2015. This will
be followed by the simultaneous drilling of the other wells and
producing gas from the first well.
Sander LandkroonProject Manager, Iv-Oil & Gas
Oil & Gas
Technical data:
Dimensions
Topside (lxwxh): 25 x 17 x 15 m
Jacket (lxwxh): 24 x 29 x 61 m (base)
Ventboom: 14 m
Weight
Topside: 1080 T (Lifting Weight) /
1110 T (Operational)
Jacket: 1360 T
Gas Pressure: 50 bar
Gas Temperature: 15oC
Water Depth: 44.5 m
Gas Capacity: 70 MMSCFD