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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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16 IVORMATIE MAGAZINE MARCH 2015 17

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