Deepwater pipeline adalah jaringan
pipa bawah laut di laut dalam. Deepwater pipeline memiliki tantangan besar
dalam hal desain dan konstruksi.
Pada Januari 2012, dnvusa.com
merilis artikel mengenai konsep baru deepwater pipeline yang dapat mengurangi
biaya, namun tidak aman. Artikel dalam bahasa asli dapat dibaca di bawah ini.
X-Stream can reduce both the pipeline wall thickness and time spent
on welding and installation compared to deep-water gas pipelines
currently in operation. The exact reduction in the wall thickness
depends on the water depth, pipe diameter and actual pipeline profile.
Typically, for a gas pipeline in water depths of 2,500 m, the wall
thickness reduction can be 25 to 30 % compared to traditional designs.
“It’s
essential for DNV that the new concept meets the strict requirements of
the existing safety and integrity regime, and I’m pleased to confirm
that this concept does,” says Dr. Henrik O. Madsen, DNV’s CEO, who
announced the news at a press briefing in London today.
“DNV has
been instrumental in developing and upgrading the safety and integrity
regime and standards for offshore pipelines over the past decades.
Today, more than 65 % of the world’s offshore pipelines are designed and
installed to DNV’s offshore pipeline standard. As the deep-water gas
transportation market will experience massive investments and
considerable growth over the coming years, new safe and cost-efficient
solutions are needed,” Dr. Madsen adds.
Current deep-water gas
pipelines have thick walls and, due to quality and safety requirements,
the number of pipe mills capable of producing the pipe is limited. When
installing pipelines, the heavy weights are difficult to handle and the
thick walls are challenging to weld. And finally, the number of
pipe-laying vessels for deep-water pipelines is limited too.
New
offshore oil and gas fields are being developed in deeper and deeper
waters and export solutions for the gas are critical. New exploration
activities are also heading for ultra-deepwaters. The distance to shore
is increasing too. The X-Stream concept can for such fields represent an
alternative to e.g. floating LNG plants combined with LNG shuttle
tankers.
By controlling the pressure differential between the
pipeline’s external and internal pressures at all times, the amount of
steel and thickness of the pipe wall can be reduced by as much as 25-30 %
- or even more compared to today’s practice and depending on the actual
project and its parameters. This will of course make it easier and
cheaper to manufacture and install the pipeline.
“By utilising an
inverted High Pressure Protection System – i-HIPPS – and inverted Double
Block and Bleed valves – i-DBB – the system immediately and effectively
isolates the deep-water pipe if the pressure starts to fall. In this
way, the internal pipeline pressure is maintained above a critical level
for any length of time,” explains Asle Venås, DNV’s Global Pipeline
Director.
The new concept is simple and reliable. During
installation, it is necessary to fully or partially flood the pipeline
to control its differential pressure. During operation, the i-HIPPS and
i-DBB systems ensure that the pipeline’s internal pressure can never
drop below the collapse pressure – plus a safety margin. In sum – a
certain minimum pressure will be maintained in the pipeline at all
times.
“It will also be important to maintain the minimum pressure
in the pipeline during pre-commissioning. This can be done using
produced gas separated from the water in the pipe by a set of separation
pigs and gel. This technology is not new to the industry. This method
has already been initiated as standard practice by several oil
companies,” says Mr Venås.
A team of mainly young highly skilled
engineers, headed by DNV in Rio de Janeiro, Brazil, is behind the
X-Stream concept. As with the other DNV concepts launched in 2010 and
2011, the X-Stream team was asked to think outside the box.
The
DNV study is a concept study, and a basic and detailed design will need
to be carried out before the X-Stream concept is realised on a real
project. DNV intends to work further with the industry to refine and
test the concept.
“I’m pleased to announce the outcome of this
innovation project. At DNV, we feel confident that, by further
qualifying the X-Stream concept, huge financial savings can be made for
long distance, deep-water gas pipelines without compromising pipeline
safety and integrity,” concludes Dr. Madsen.
Sumber: dnvusa.com
